Skip to main content
NCBI home page
Ecology and Evolution logoLink to Ecology and Evolution
. 2019 May 9;9(11):6329–6341. doi: 10.1002/ece3.5205

Evidence of stress imprinting with population‐level differences in two moss species

Weiqiu Liu 1,✉, Jianqu Xu 1, Wei Fu 1, Xiangyuan Wang 1, Chunyi Lei 2, Yunfeng Chen 1
PMCID: PMC6580294  PMID: 31236224

Abstract

Plants are often repeatedly exposed to stresses during their lives and have a mechanism called stress imprinting that provides “memories” of stresses they experience and increases their ability to cope with later stresses. To test hypotheses that primed bryophytes can preserve their stress imprinting after 6 days of recovery and induce higher levels of osmolytes and ROS‐scavenging activities upon later stress exposure, and there exist population‐level differentiation in their desiccation defenses, we transplanted samples of two populations of each of two moss species, Hypnum plumaeforme and Pogonatum cirratum, in a nature reserve in southern China. After 16 months of acclimation, sets of each population were subjected to control, one‐time desiccation stress, duplicated desiccation stress and cross‐stress (low temperature stress followed by desiccation stress) treatments. Levels of oxidant enzymes, osmolytes, and phytohormones in the samples were then determined. The desiccation stress generally led to increases in activities or contents of superoxide dismutase, guaiacol peroxidase, catalase, proline, soluble sugars, soluble proteins, and stress hormones including abscisic acid (ABA), jasmonates (JA), and salicylic acid (SA), with differences between both species and populations. After a 6‐day recovery period, contents of phytohormones (including ABA, JA, SA, and cytokinins) in stressed H. plumaeforme had substantially fallen toward control levels. The duplicated and cross‐stress treatments generally led to further accumulation of proline, soluble sugars, and soluble proteins, with further increases in activities of antioxidant enzymes in some cases. Furthermore, significant differences between allochthonous and native populations were found in contents of malondialdehyde and osmolytes, as well as antioxidant enzyme activities. Our results confirm the hypotheses and highlight the importance of osmolytes in mosses' stress responses.

Keywords: bryophytes, desiccation, osmolytes, phytohormones, population differentiation, stress imprint

1. INTRODUCTION

Land plants are frequently challenged by diverse environmental stresses as they cannot escape from adverse environments. Hence, they have evolved vital survival mechanisms that enable them to sense and adapt to the stresses. Phytohormones are key messengers that integrate external stress signals with internal metabolic activities (Kohli, Sreenivasulu, Lakshmanan, & Kumar, 2013; Peleg & Blumwald, 2011; Verma, Ravindran, & Kumar, 2016; Verslues, 2016). Abscisic acid (ABA), jasmonates (JA), salicylic acid (SA), and ethylene, which are defined as stress phytohormones, generally increase in stress conditions (Bruce, Matthes, Napier, & Pickett, 2007). Others, such as auxins, gibberellins, and cytokinins, are also involved in stress responses via complex signaling networks (Verma et al., 2016; Verslues, 2016). Phytohormones regulate stress responses that often include increases in antioxidant capacity and accumulation of osmolytes (Cvikrová et al., 2012; De Diego et al., 2013; Hüve, Bichele, Tobias, & Niinemets, 2006; Liu, Lei, Jin, et al., 2015; Nagao, Minami, Arakawa, Fujikawa, & Takezawa, 2005; Zhao, Shi, Liu, Jia, & Li, 2015). Furthermore, information about experienced stresses (“stress memories” or “stress imprints”) can be stored in plants and may often increase their tolerance of recurrent stresses (Bruce et al., 2007; Nikiforou & Manetas, 2018). Phytohormone regulation and accumulation of antioxidants and osmolytes in response to previous stress are considered important elements of stress imprinting (Asensi‐Fabado, Oliván, & Munné‐Bosch, 2013; Bruce et al., 2007; Walter, Jentsch, Beierkuhnlein, & Kreyling, 2013). As various abiotic stresses, such as low temperature and drought, can induce some similar physiological responses, they may cause cross‐stress imprinting in higher plants (Blödner, Skroppa, Johnsen, & Polle, 2005; Walter et al., 2013).

For bryophytes, plenty of studies has demonstrated that experienced desiccation can make them adapt to desiccation stress better (Beckett, 1999; Beckett, Marschall, & Laufer, 2005; Bopp & Werner, 1993; Dilks & Proctor, 1976; Schonbeck & Bewley, 1981a, 1981b; Werner, Ros Espín, Bopp, & Atzorn, 1991); however, this stress imprinting tends to wear off with the extension of the recovery time, and slower desiccation rates produce longer imprinting times (Brinda, Stark, Clark, & Greenwood, 2016). For naturally growing mosses in the field, water between dense individuals generally leads to relatively slow desiccation rates and the intervals between dry events varied. It has been reported that a period of more than 7 days is required to remove the acclimation experience (Hájek & Vicherová, 2014; Hellwege, Dietz, Volk, & Hartung, 1994; Stark, Greenwood, Brinda, & Oliver, 2014), and studies have also demonstrated that levels of osmolytes and antioxidants may increase in mosses upon exposure to low temperature or water stress, and may remain relatively high even after alleviation of stresses for 10 days (Liu et al., 2016; Liu, Lei, Jin, et al., 2015). So, we hypothesized that the priming information can be stored in mosses for a certain time (e.g., 6–10 days) and induce higher tolerance to a later stress. A complicating factor is that populations within a species' distribution are often exposed to different environmental conditions and thus develop local adaptations (Briggs, 1972; Chambers & Emery, 2016; Lázaro‐Nogal et al., 2016). As both selective environmental pressures and gene flow limitations drive differentiation, between‐population distances and dispersal potentials both affect the extent of population‐level differentiation (Chambers & Emery, 2016; Korpelainen, Pohjamo, & Laaka‐Lindberg, 2005). Moreover, due to the limited dispersal potential of bryophytes, significant population differentiation can be found within quite a small area (Briggs, 1972; Snäll, Ribeiro, & Rydin, 2003). Although population differentiation of bryophytes has received some attention, studies have generally focused on their morphological and life‐history traits (Hedderson & Longton, 2008) or direct determination of their genetic structure (Pohjamo, Korpelainen, & Kalinauskaitė, 2008; Wang, Zhu, & Wang, 2012). Between‐population differences in their physiological traits have received much less attention despite their importance in species' fitness. However, it is clearly important to characterize and distinguish such differentiation and stress imprinting mechanisms (if present) in attempts to clarify bryophytes' suites of stress responses.

Hypnum plumaeforme is a widespread species in China, and Pogonatum cirratum is also widely distributed but mainly in tropical and subtropical China. The two mentioned species (Figure 1) were selected as test plants because of their wide distribution and good survival after transplanting, which make them suitable for population‐level differentiation study. In the study presented here, samples of two populations of each species at sites with substantially different environments were collected and transplanted in a subtropical nature reserve in southern China. After 16 months of acclimation, they were subjected to several stress regimes. We then determined and compared their antioxidant enzyme activities and levels of both osmolytes and phytohormones. The following hypotheses were tested as follows: Mosses have stress imprinting mechanisms; antioxidant enzymes, osmolytes, and phytohormones are involved in the mechanisms; and there are significant between‐species and population‐level differences in the mosses' stress tolerance. We also expected to find greater differentiation between the two H. plumaeformae populations than between the two P. cirratum populations, because the latter are geographically closer to each other.

Figure 1.

Figure 1

Open in a new tab

Photographs of (a) controlled Hypnum plumaeforme, (b) desiccated Hypnum plumaeforme, (c) controlled Pogonatum cirratum, and (d) desiccated Pogonatum cirratum collected from Heishiding Nature Reserve. Water was supplied every 2 days for the controlled samples and was withheld for 12 days for the desiccated samples

2. METHODS AND MATERIALS

2.1. Plants and treatment design

In October 2015, we collected samples of H. plumaeforme representing populations located in Heishiding Nature Reserve (23°25′–23°29′N, 111°49′–111°55′E; 400–500 m a.s.l.) and on Mount Lushan (29°26′–29°41′N, 115°52′–116°8′E; 1,000–1,200 m a.s.l.), as well as samples of P. cirratum representing populations located in Heishiding Nature Reserve (400–500 m a.s.l.) and on Mount Jinggangshan (26°13′–26°53′N, 113°56′–114°18′E; 800–900 m a.s.l.). The distance between the pairs of H. plumaeforme and P. cirratum populations was about 800 and 400 km, respectively (Figure 2). Collected mosses were transplanted to a valley bottom at the edge of the forest in Heishiding Nature Reserve as soon as possible. Environmental details of this site have been previously published (Liu, Lei, Jin, et al., 2015; Liu, Liu, Lei, Zhang, & Guo, 2011). Gametophytes of each population were planted in 12 trays (30 × 50 cm) assigned (in triplicate) to four treatment regimes: control (CK), one‐time desiccation stress (OD), duplicated desiccation stress (DD), and cross‐stress (low temperature followed by desiccation stress, TD). The planting density was similar to that of their natural communities. The treatments (each including a 6‐day recovery period between the C, D, or T phase) are graphically illustrated and explained in Figure 3. The mosses were acclimated in the field until February 2017, during which they were watered every 3 days. According to the records of a weather station located in the nature reserve, the mean annual temperature in 2016 is 19.5°C, with an average temperature of the hottest month (August) and coldest month (February) of 26.3°C and 10.3°C, respectively. The annual rainfall in the study area is 2096 mm, with the highest monthly rainfall in August (355 mm) and lowest in December (2.3 mm). In February 2017, trays assigned to the CK, OD, and DD treatments were moved to a wire cage near the valley and watered according to the schedule shown in Figure 3. Six days after the start of these treatments, the TD trays were moved to a climate chamber with the temperature set to 1 and 3°C in 12‐hr light (50 μmol m−2 s−1) and 12‐hr dark periods, respectively, and the relative humidity (RH) set to 85%, and 3 days later, they were also moved to the wire cage and exposed to the same conditions as the OD samples (Figure 3). During the treatment period (from February 27 to March 30), the mean temperature is 16.2°C and the total rainfall is 121.2 mm, with the RH in the wire cage generally higher than 80% as aperiodically measured using a hygrothermograph (TES 1361, Taiwan). After the first desiccation treatment, both species showed significant morphological difference with the control group (Figure 1) and the water content in desiccated and controlled samples was 0.24 ± 0.03 g/g DW and 1.34 ± 0.24 g/g DW for P. cirratum, and 0.27 ± 0.04 g/g DW and 2.42 ± 0.32 g/g DW for H. plumaeforme.

Figure 2.

Figure 2

Open in a new tab

Geographic locations of the sampled populations

Figure 3.

Figure 3

Open in a new tab

Overview of the treatment regimes. In D treatment periods, no water was supplied to the mosses, but during the other treatment periods, water was supplied every 2 days. The mosses were exposed to ambient temperatures (7–26°C) during C, D, and recovery periods. During T treatment periods, the mosses were placed in a climate chamber providing 12‐hr light/12‐hr dark cycles, with temperatures of 3 and 1°C during the light and dark phases, respectively, and 50 μmol m−2 s−1 illumination during the light phases

Samples of the top 2 cm of gametophytes (ca. 2 g) representing each triplicated species, population, and treatment combination were collected for determination of phytohormones and other physiological indices immediately after the CK, OD, DD, and TD treatments. Samples of H. plumaeforme assigned to DD and TD treatments were also collected to determine their phytohormone levels immediately after the 6‐day recovery period. Samples were washed with distilled water for three times to remove debris and sand, and then excess water was blotted with paper sheets. Samples for phytohormone analyses were stored at −80°C prior to determination. Other samples were stored at −20°C and analyzed within 48 hr.

2.2. Malondialdehyde and soluble protein contents and activities of superoxide dismutase (E.C. 1.15.1.1), guaiacol peroxidase (EC 1.11.1.7), and catalase (EC 1.11.1.6)

About 0.5 g of each moss sample was weighed and ground with 7 ml ice‐cold 0.1 M phosphate‐buffered saline (PBS) buffer (pH 7.8) containing 0.1 mM ethylenediaminetetraacetic acid‐Na2, 3% (m/v) polyvinylpolypyrrolidone, 0.06% (v/v) Triton X‐100, and 5% (v/v) glycerol. The mixture was centrifuged at 12,000 rpm for 5 min at 4°C, and the supernatant was used for measurements.

Malondialdehyde (MDA) content was determined according to the handbook of the Shanghai Institute of Plant Physiology, CAS (Shanghai Institute of Plant Physiology Chinese Academy of Sciences (SIPP), 1999). Superoxide dismutase (SOD) activity was determined by measuring inhibition of the photochemical reduction of nitro blue tetrazolium (NBT; Yu & Rengel, 1999), as previously described (Liu, Lei, Shu, et al., 2015). Catalase (CAT) activity was determined spectrophotometrically by monitoring decomposition of H2O2 at 240 nm, as follows (Beers & Sizer, 1952). A 0.2 ml portion of each extract was added to 2.5 ml of 0.1 M PBS (pH 7.8). The reaction was initiated by adding 0.5 ml of 0.1 M H2O2, and 1 unit of CAT activity was defined as the amount of enzyme causing a 0.1 per min decline in OD240. Total guaiacol peroxidase (POX) activity was determined by monitoring formation of tetraguaiacol from guaiacol at 470 nm for 4 min in the presence of H2O2 (Shanghai Institute of Plant Physiology Chinese Academy of Sciences (SIPP), 1999). In these assays, portions (0.4 ml) of the extracts were added to 30 ml of 0.1 M PBS (pH 6.0) and 1.4 µl guaiacol. The reaction was initiated by adding 0.85 µl of 30% H2O2, and 1 unit of POX activity was defined as the amount of enzyme causing a 0.01 per min reduction in OD470. In both CAT and POX assays, portions of boiled extract served as blanks.

2.3. Proline contents

Proline was extracted using sulfosalicylic acid, as previously described (Wang & Huang, 2015). About 0.5 g of each sample was ground with 5 ml extraction solution (3% sulfosalicylic acid) and transferred to a test tube, then boiled for 10 min. After cooling to room temperature and centrifugation at 6,000 rpm for 10 min, the supernatant was used to determine proline contents following Troll and Lindsley (1955), with minor modification. Briefly, a 2 ml portion of each extract was mixed with 2 ml glacial acetic acid and 2 ml of 2% ninhydrin in ethanol‐glacial acetic‐phosphoric acid solution (25:60:15, by volume) then boiled for 40 min. After cooling, 3.5 ml of toluene was added, and the mixture was shaken vigorously and left to stand until it had delaminated. The toluene phase was collected and added to 0.5 ml methanol then analyzed spectrophotometrically at 520 nm. Toluene was used for blanks.

2.4. Soluble sugar contents

The samples' soluble sugar contents were determined according to SIPP (Shanghai Institute of Plant Physiology Chinese Academy of Sciences (SIPP), 1999). Samples of about 0.3 g were weighed and ground in liquid nitrogen, then 20 ml of ice‐cold 80% ethanol was added, and the samples were ground again for 3–5 min. Each mixture was transferred to a conical flask, extracted at 80°C for 30 min, and then (after cooling) subjected to negative‐pressure filtration. The filtrate was diluted to 50 ml and transferred to a new conical flask, 0.5 ml of saturated lead subacetate solution was added, and the mixture was shaken vigorously. Then, 0.2 g sodium oxalate was added, and the mixture was refiltered. A portion (0.5 ml) of the resulting filtrate was added to 0.5 ml 80% ethanol and 5 ml anthrone reagent (containing 0.2% anthrone and 76% H2SO4), boiled for 2 min, and after cooling analyzed spectrophotometrically at 630 nm. Sucrose was used as a calibration standard.

2.5. Phytohormone contents

ABA, JA, SA, cis‐zeatin (cis‐Z), cis‐zeatin riboside (cis‐ZR), trans‐zeatin (trans‐Z), and IAA contents were extracted, purified, and analyzed by solid phase extraction followed by ultraperformance liquid chromatography coupled to electrospray‐tandem mass spectrometry (UPLC/ESI‐MS/MS), as previously described (Cao, Ma, Mou, Yu, & Chen, 2015; Liu, Li, Xiao, & Wang, 2012).

Samples (0.2 g FW) were added to 1.5 ml extraction solvent (methanol:water:methane acid, 7.9:2:0.1, v/v/v) in 5‐ml microcentrifuge tubes with two steel balls (D = 4 cm) in each tube and broken using a Tissuelyser‐48 multisample tissue grinder (Jingxing, Shanghai) for 3 min. Then, the samples were extracted by ultrasonication (40 kHz, 30 min) on ice, centrifuged (4,000 rpm, 3 min, at 4°C), and extracted at 4°C for 12 hr. After centrifugation (12,000 rpm for 20 min at 4°C), the supernatant was collected and the pellet was reextracted with 1.0 ml of extraction solvent. Then, supernatants were combined and purified using a MAX SPE column (60 mg, 3 ml, Waters, USA) conditioned with 4 ml methanol followed by 2 ml of 0.1 M NH4NO3. For this, each sample was added to the column, which was then washed with 2 ml of 0.1 M NH4NO3 followed by 2 ml of 60% methanol containing 0.1 M NH4NO3. Analytes were eluted with 2.5 ml of 70% methanol containing 1.25 M methane acid. The eluate was dried completely using a vacuum concentrator and redissolved in 0.15 ml of initial mobile phase (acetonitrile:methane acid:water, 5:0.1:94.9, v/v/v) and filtered through a 0.20 μm Nylon filter (Lumeng).

Samples (3 μl) were then analyzed by ultraperformance liquid chromatography–electrospray‐tandem mass spectrometry (UPLC/ESI‐MS/MS). Levels of phytohormones in the samples were quantified using calibration curves obtained from analyses of external standard solutions of IAA, cis‐zeatin (cis‐Z), cis‐zeatin riboside (cis‐ZR), trans‐zeatin (trans‐Z), ABA, JA, and SA (Sigma‐Aldrich). Presented results indicate averages obtained from three injections of each sample. The UPLC system consisted of an Acquity UPLC™ System (Waters) quaternary pump coupled to an autosampler and a Waters Acquity UPLC HSS T3 column (100 × 2.1 mm, 1.7 μm). The mobile phase consisted of a gradient of A:B, time (min) as (95:5, 1), (30:70, 1), and (95:5, 1), where A is 0.1% methane acid in water and B is 0.1% methane acid in acetonitrile, at a constant flow rate of 0.4 ml/min. A XevoTM TQ‐S Tandem Quadrupole mass spectrometer (Waters MS Technologies, Milford, MA, USA) was used for the MS and MS/MS analyses in MRM (multiple reaction monitoring) mode. For analyses of IAA and cytokinins (including cis‐Z, cis‐ZR, and trans‐Z), we used a Turbo Ionspray source in positive ion mode, with 2.5 kV capillary voltage for IAA and 3.0 kV for cytokinins; 22 V cone voltage for IAA and 10 V for cytokinins; 22 V collision voltage for IAA, cis‐Z, and trans‐Z; and 20 V for cis‐ZR. Quantitative data were obtained using peaks of 176.0, 220.0, 220.0, and 352.1 m/z precursor ions together with peaks of 130.3, 118.8, 135.9, and 220.1 m/z production ions for IAA, cis‐Z, trans‐Z, and cis‐ZR, respectively. ABA, JA, and SA were analyzed using the Turbo Ionspray source in negative ion mode, with 1.5 kV capillary voltage, 18 V cone voltage, and collision voltage set at 30, 25, and 20 V for ABA, JA, and SA, respectively. Quantitative data were obtained using peaks of 263.0, 209.0, and 136.8 m/z precursor ions together with peaks of 152.9, 58.8, and 93.0 m/z production ions, respectively.

2.6. Data analysis

Means and standard errors of each measured variable were calculated. Differences between treatments within each population were analyzed using one‐way ANOVA, and Tukey's test (or Dunnett's test when homogeneity of variance requirements was not met) was used to identify differences significant at the 0.05 probability level. Log‐transformation was applied when necessary. In addition, between‐treatment and between‐population differences were explored by two‐way ANOVA. Differences in variables are regarded as significant if p < 0.05, and only mentioned if they meet this criterion. Increases or decreases in variables refer to measured differences between stressed samples and corresponding controls after the treatments unless otherwise stated.

3. RESULTS

3.1. Oxidative stress

The stress treatments stimulated accumulation of antioxidant enzymes but did not cause significant changes in MDA contents of H. plumaeforme. In the Heishiding population of H. plumaeforme (hereafter, H‐Heishiding), SOD and POX activities increased under all stress treatments, but CAT activity only under the DD treatment. In samples of the Lushan population of H. plumaeforme (H‐Lushan), SOD activities increased under DD and TD treatments, while CAT and POX activities increased under DD and OD treatments, respectively (Figure 4). Results of two‐way ANOVA showed that MDA contents and activities of all assayed antioxidant enzymes were higher in H‐Lushan samples than in H‐Heishiding samples (Figure 4, Table 1).

Figure 4.

Figure 4

Open in a new tab

Malondialdehyde (MDA) contents and activities of superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (POX) in Hypnum plumaeforme and Pogonatum cirratum gametophytes after indicated stress treatments (mean + 1 SE, n = 3). CK, OD, DD, and TD refer to control, one‐time desiccation stress, duplicated desiccation stress, and low temperature followed by desiccation stress, respectively. Different lowercase letters above columns denote significant difference between treatments within each population (one‐way ANOVA with Tukey's post hoc test). H‐Heishiding and H‐Lushan refer to Heishiding and Lushan populations of H. plumaeforme, respectively, while P‐Heishiding and P‐Jinggangshan refer to Heishiding and Jinggangshan populations of P. cirratum, respectively. Note the difference in scales for POX activities in the two moss species

Table 1.

Effects of population (H‐Heishiding and H‐Lushan) and treatment (control, one‐time desiccation stress, duplicated desiccation stress, and cross‐stress) on oxidative and osmotic indices in Hypnum plumaeforme as shown by F‐values and p‐values (p‐values in parentheses) from two‐way ANOVA

  df MDA SOD CAT POX Pro SS SP
Population (P) 1 28.5 (<0.001) 150.5 (<0.001) 246.1 (<0.001) 162.6 (<0.001) 84.0 (<0.001) 83.8 (<0.001) 209.8 (<0.001)
Treatment (T) 3 1.55 (0.241) 72.3 (<0.001) 15.6 (<0.001) 21.0 (<0.001) 65.6 (<0.001) 114.1 (<0.001) 54.7 (<0.001)
T × P 3 1.61 (0.227) 14.1 (<0.001) 4.96 (0.013) 2.1 (0.147) 10.5 (<0.001) 8.4 (0.001) 21.3 (0.001)
Open in a new tab

Non‐significant effects with p > 0.05 are highlighted in bold.

MDA contents were significantly higher in stressed P. cirratum samples than in the controls, and the DD treatment caused greater increases in samples of the Heishiding population of P. cirratum (P‐Heishiding) than the OD and TD treatments (Figure 4). SOD activities in samples of P‐Heishiding also increased under stress conditions, and both the DD and TD treatments caused stronger increases than the OD treatment. However, the stress treatments did not significantly affect SOD activity in the Jinggangshan population of P. cirratum (P‐Jinggangshan). OD and TD (but not DD) treatments caused significant increases in CAT activities in both populations. POX activities in P‐Jinggangshan samples were significantly increased by the OD treatment, and the DD and TD treatments led to further increases, but in P‐Heishiding samples, the TD treatment caused a decrease in POX levels (Figure 4). Differences in SOD activities between the two P. cirratum populations were not significant, but CAT and POX activities were significantly higher in P‐Jinggangshan samples than in P‐Heishiding samples (Figure 4, Table 2).

Table 2.

Effects of population (P‐Heishiding and P‐Jinggangshan) and treatment (control, one‐time desiccation stress, duplicated desiccation stress, and cross‐stress) on oxidative and osmotic indices in Pogonatum cirratum as shown by F‐values and p‐values (p‐values in parentheses) from two‐way ANOVA

  df MDA SOD CAT POX Pro SS SP
Population (P) 1 6.7 (0.020) 0.26 (0.618) 30.6 (<0.001) 245.9 (0.001) 406.8 (<0.001) 1.5 (0.236) 23.6 (<0.001)
Treatment (T) 3 45.8 (<0.001) 14.1 (<0.001) 10.6 (<0.001) 49.1 (<0.001) 62.1 (<0.001) 261.2 (<0.001) 46.6 (<0.001)
T × P 3 4.9 (0.014) 5.3 (0.010) 0.728 (0.550) 65.7 (<0.001) 6.5 (0.004) 2.4 (0.105) 12.2 (<0.001)
Open in a new tab

Non‐significant effects with p > 0.05 are highlighted in bold.

3.2. Osmolytes

The stress treatments caused significant accumulation of proline, soluble sugars, and soluble proteins in both mosses. In H. plumaeforme, DD and TD treatments caused higher accumulation of proline than OD, while in P. cirratum, contents of soluble sugars and soluble proteins were higher in DD and TD samples (except for soluble proteins in TD samples of the P‐Heishiding population) than in OD samples (Figure 5). Results of two‐way ANOVA showed that contents of proline, soluble sugars, and soluble proteins were generally higher in allochthonous populations than in native populations (except for soluble sugars in P. cirratum) (Table 1).

Figure 5.

Figure 5

Open in a new tab

Proline, soluble sugar, and soluble protein contents in gametophytes of Hypnum plumaeforme and Pogonatum cirratum subjected to indicated stress treatments (mean + 1 SE, n = 3). CK, OD, DD, and TD refer to control, one‐time desiccation stress, duplicated desiccation stress, and low temperature followed by desiccation stress, respectively. Different lowercase letters above columns denote significant difference between treatments within each population (one‐way ANOVA with Tukey's post hoc test). H‐Heishiding and H‐Lushan refer to Heishiding and Lushan populations of H. plumaeforme, respectively, while P‐Heishiding and P‐Jinggangshan refer to Heishiding and Jinggangshan populations of P. cirratum, respectively

3.3. Phytohormones

The stresses caused sharp increases in ABA contents in H. plumaeforme: up to 11.4‐ and 16.7‐fold in H‐Heishiding and H‐Lushan samples, respectively (Figure 6). The DD and TD treatments caused higher rises than the OD treatment in H‐Lushan samples, but the OD treatment induced the highest levels in H‐Heishiding samples. JA and SA levels also increased under the stresses. In samples of both H. plumaeforme populations, the DD treatment caused lower increases in JA contents than the OD and TD treatments. However, changes in SA contents of the two populations differed. The OD and DD treatments resulted in greater increases than the TD treatment in H‐Lushan samples, but the TD treatment caused the greatest increase in H‐Heishiding samples. After the recovery (R) period, ABA, JA, and SA contents were all lower in samples that had been subjected to D or T stresses (designated DR and TR, respectively) than in OD, DD, and TD samples. However, ABA contents of DR samples and both JA and SA contents of DR samples of the H‐Heishiding population were still significantly higher than those of corresponding controls. In addition, ABA, JA, and SA contents were higher in DR samples than in TR samples of both populations, but the differences were strongest in H‐Heishiding samples (Figure 6).

Figure 6.

Figure 6

Open in a new tab

ABA, JA, SA, IAA, cis‐Z, cis‐ZR, and trans‐Z contents in gametophytes of Hypnum plumaeforme subjected to indicated stress treatments (mean + 1 SE, n = 3). CK, OD, DD, and TD refer to control, one‐time desiccation stress, duplicated desiccation stress, and low temperature followed by desiccation stress. DR and TR indicate contents measured after 6 days of recovery from the first desiccation or low temperature treatment. Different lowercase letters above columns denote significant difference between treatments within each population (one‐way ANOVA with Tukey's post hoc test). Data were log‐transformed before further analysis

Sharp increases in ABA content after the stress treatments were also observed in P. cirratum samples: up to 12.8‐ and 57.8‐fold in P‐Heishiding and P‐Jinggangshan samples, respectively (Figure 7). Moreover, the duplicated and cross‐stress treatments caused further increases in JA contents of P‐Jinggangshan samples, while SA levels were highest in one‐time stressed samples (Figure 7). In sharp contrast, the stresses did not increase (and in some cases decreased) JA and SA contents in P‐Heishiding samples.

Figure 7.

Figure 7

Open in a new tab

ABA, JA, SA, IAA, cis‐Z, cis‐ZR, and trans‐Z contents in gametophytes of Pogonatum cirratum subjected to indicated stress treatments (mean + 1 SE, n = 3). CK, OD, DD, and TD refer to control, one‐time desiccation stress, duplicated desiccation stress, and low temperature followed by desiccation stress. Different lowercase letters above columns denote significant differences between treatments within each population (one‐way ANOVA with Tukey's post hoc test, in all cases except JA in P‐Jinggangshan, for which Dunnett's test was applied). Data were log‐transformed before further analysis

Contents of the cytokinins cis‐Z, trans‐Z, and cis‐ZR widely varied, with ranges of 6.7–21.9, 0.07–0.31, and 0.002–0.066 ng/g FW, respectively, in H. plumaeforme, and ranges of 1.23–36.72, 0.03–0.17, and 0.05–0.15 ng/g FW, respectively, in P. cirratum (Figures 6 and 7).

The stress treatments caused increases in contents of cis‐Z, cis‐ZR, and trans‐Z in H. plumaeforme. After the 6‐day recovery period, the cis‐ZR and trans‐Z contents of DR and TR samples were lower than in OD, DD, and TD samples, but cis‐Z levels were only significantly lower in H‐Heishiding samples, in which levels of cis‐Z and trans‐Z were higher in DR samples than in TR samples (Figure 6).

The patterns of cytokinin responses showed substantial population‐level differences in P. cirratum. In P‐Heishiding samples, the stresses induced increases in cis‐Z levels and reductions in cis‐ZR and trans‐Z levels, while almost opposite changes were observed in P‐Jinggangshan samples (Figure 7).

There were no clear patterns in responses of IAA to the stresses in either species (Figure 8).

Figure 8.

Figure 8

Open in a new tab

Mean (+1 SE, n = 3) IAA contents in gametophytes of Hypnum plumaeforme and Pogonatum cirratum subjected to indicated stress treatments. CK, OD, DD, and TD refer to control, one‐time desiccation stress, duplicated desiccation stress, and low temperature followed by desiccation stress. DR and TR indicate contents measured after 6 days of recovery from the first desiccation or low temperature treatment. Different lowercase letters above columns denote significant difference between treatments within each population (one‐way ANOVA with Tukey's post hoc test). Data were log‐transformed before further analysis. H‐Heishiding and H‐Lushan refer to Heishiding and Lushan populations of H. plumaeforme, respectively, while P‐Heishiding and P‐Jinggangshan refer to Heishiding and Jinggangshan populations of P. cirratum, respectively

4. DISCUSSION

4.1. Antioxidant enzyme activities and osmotic regulation

Stress conditions typically result in overproduction of reactive oxygen species (ROS) and lipid peroxidation in plants (Deeba et al., 2012). Thus, an indicator of lipid peroxidation, MDA, is also often used as an indicator of oxidative stress in plants. Although there has been reported that the membrane damage of Fontinalis antipyretica by dehydration is due to nitric oxide end products rather than MDA (Cruz de Carvalho, Catalá, Branquinho, Marques da Silva, & Barreno, 2017), we have found significant increase in MDA in H. plumaeforme and P. cirratum upon exposure to water stress (Liu, Lei, Jin, et al., 2015). On the other hand, stress conditions generally induce increases in activities of antioxidant, ROS‐scavenging enzymes such as SOD, CAT, and POX (Sofo, Dichio, Xiloyannis, & Masia, 2004). Our results showed that stresses stimulated increases in activities of SOD, CAT, and POX in both species, but significant increases in MDA levels were only observed in P. cirratum. These observations suggest that the stresses triggered antioxidant defense mechanisms that neutralized ROS sufficiently to avoid significant cell membrane damage in H. plumaeforme, but P. cirratum is more sensitive to water stress and the treatments caused damage to its membranes. Proline, soluble sugar, and soluble proteins are osmolytes, which often accumulate in plants upon exposure to osmotic stress (Ahmad et al., 2016; Cruz de Carvalho, Bernades da Silva, Branquinho, & Marques da Silva, 2015; Cruz de Carvalho et al., 2014; Mittal, Kumari, & Sharma, 2012; Nagao et al., 2005), and our results show that the stresses also led to their accumulation in the mosses.

In previous studies, we found that after a 10‐day recovery period stressed mosses still maintained relatively high levels of SOD and osmolytes (Liu et al., 2016; Liu, Lei, Jin, et al., 2015). In the present study, we found that proline, soluble sugar, and soluble protein contents were higher after duplicated and cross‐stress treatments than after one‐time stress treatments. These results indicate that the first stress primed accumulation of osmolytes in the mosses when subjected to the second stress, and improved their adaptation to the later stress. Thus, they confirm two of our hypotheses: that mosses have stress imprinting mechanisms, and osmolytes are involved in them. These results also indicated that the stress imprinting can be maintained in the tested mosses for 6 days. Further increases in SOD and CAT activities in H‐Lushan, SOD in P‐Heishiding, and POX in P‐Jinggangshan samples subjected to duplicated or cross‐stresses indicated that the first stress also induced stronger increases in ROS‐scavenging activities in the mosses during exposure to the later stress (Ye & Gressel, 2000). On the other hand, POX activities were lower in TD samples of the Heishiding populations of both species, but not the allochthonous populations, than in corresponding OD and DD samples, highlighting the differences in low temperature responses between populations from different latitudes.

Moreover, even after a year of acclimation in Heishiding Nature Reserve, levels and activities of MDA, antioxidant enzymes, and osmolytes were still much higher in H‐Lushan than in H‐Heishiding samples. However, there were no substantial differences in SOD and soluble sugar contents or activities between the native and allochthonous populations of P. cirratum. These results indicate that population‐level differentiation is present in both species, but more strongly in H. plumaeforme than in P. cirratum. This is in accordance with our third hypothesis and suggests that geographical distance might be one of the drivers of population‐level differentiation (Chambers & Emery, 2016; Korpelainen et al., 2005), though further studies are needed to illustrate the role of geological distance in their population differentiation.

4.2. Phytohormone regulation

ABA plays key roles in mosses' stress tolerance (Beckett, 1999; Beckett, Csintalan, & Tuba, 2000; Bhyan et al., 2012; Mayaba, Beckett, Csintalan, & Tuba, 2001; Nagao et al., 2005; Xiao, Yobi, Koster, He, & Oliver, 2018). Our results show that stresses induced sharp increases in ABA contents in both species, in accordance with previous studies (Kohli et al., 2013; Xiao et al., 2018). JA and SA are generally considered to be largely involved in biotic defenses (Bari & Jones, 2009), but they also accumulate in plants during abiotic stress and can participate in regulation of abiotic stress responses (Hu, Jiang, Wang, & Yu, 2013; Singh & Usha, 2003; Wang et al., 2010). We found no previous studies on responses of JA and SA to stress in mosses (literature screening procedures not described). However, our study demonstrates that stresses induced increases in JA and SA levels in both populations of H. plumaeforme, as observed in vascular plants, but only in P‐Jinggangshan samples of P. cirratum.

Cytokinins are a large group of phytohormones, mostly N 6‐substituted adenine derivatives, which are strongly associated with growth and development, and generally considered to be negative regulators of abiotic stress signaling (Nishiyama et al., 2011; Verslues, 2016). Short‐term or mild stresses generally stimulate accumulation of cytokinins, while prolonged or more severe stresses are generally associated with downregulation of active cytokinin levels (Ha, Vankova, Yamaguchi‐Shinozaki, Shinozaki, & Tran, 2012; Havlová et al., 2008; Nishiyama et al., 2011). However, no studies on responses of cytokinins to stresses in mosses have been reported (literature screening procedures not described). Cis‐Z and trans‐Z are generally the most abundant cytokinin species in mosses (Drábková, Dobrev, & Motyka, 2015; Gajdošová et al.,2011), and our results show that cis‐Z was almost 2 orders of magnitude more abundant than trans‐Z in the two species considered here. In addition, stresses induced accumulation of cis‐Z, cis‐ZR, and trans‐Z in both populations of H. plumaeforme, but in P. cirratum, there were differences in responses both among cytokinins and between populations.

After the 6‐day recovery period, the elevated JA, SA, cis‐Z, cis‐ZR, and trans‐Z contents in stressed H. plumaeforme samples had decreased significantly toward control levels. Such reductions in levels of stress response substances after recovery, and enhancement of defense mechanisms only when stress recurs, avoid costs of constitutive activation of stress responses (Brinda et al., 2016; Bruce et al., 2007; Cruz de Carvalho et al., 2014). However, their ABA levels were still higher than in control samples after recovery, which might promote faster and better responses to later stresses as most stress responses are ABA‐mediated (Bopp & Werner, 1993; Hellwege et al., 1994; Kohli et al., 2013).

Upon exposure to duplicated or cross‐stresses, we detected further accumulations of trans‐Z in samples of both H. plumaeforme populations, and of cis‐Z in H‐Heishiding samples, which might be associated with stress imprinting. Moreover, we detected substantial between‐hormone, between‐species, and between‐population variations in responses, reflecting the sensitivity and complexity of phytohormone regulation in stress responses. Due to the complex crosstalk among phytohormones (Kohli et al., 2013; Verma et al., 2016) as well as the involvement of epigenetic changes in stress responses, more detailed and specific studies are needed to elucidate the underlying mechanisms of hormone regulation in the mosses' stress imprinting.

5. CONCLUSION

Desiccation stress induced increases in antioxidant enzyme activities and contents of osmolytes and ABA in the mosses. Though with substantial between‐species and population‐level differences, the first desiccation or low temperature stress led to further increases in levels or activities of osmolytes and antioxidant enzymes upon exposure to the later desiccation stress after 6 days of recovery, indicating that the stress imprinting in the mosses can be maintained for at least 6 days. Significantly higher levels or activities of MDA, SOD, CAT, POX, and osmolytes were detected in the allochthonous population of H. plumaeforme than in the native population even after one year of acclimation, indicating distinct population differentiation, but the differentiation between the populations of the P. cirratum was weaker, which might be related to their closer geographical distance.

CONFLICT OF INTEREST

None declared.

AUTHOR CONTRIBUTIONS

WQ Liu was responsible for the design and implementation of the entire study. JQ Xu and WQ Liu carried out the study, including fieldwork, laboratory experiments, data analysis, and drafting the manuscript. W Fu, XY Wang, and YF Chen participated in the laboratory experiments, data analysis, and drafting the manuscript. CY Lei collected the weather data during the study period and participated in the fieldwork and laboratory experiments. WQ Liu, YF Chen, and CY Lei critically revise the manuscript. All authors gave the final approval of the version to be published.

DATA ACCESSIBILITY

The data of ROS, osmolytes, and phytohormones: Dryad https://doi.org/10.5061/dryad.833qr19.

ACKNOWLEDGMENTS

This research was supported by the National Natural Science Foundation of China (Grant nos. 31370490 and 31070470) and the Basic Work Special Project of the National Ministry of Science and Technology of China (Grant no. 2013FY111500). We thank the editor of Sees‐Editing Ltd. for linguistic improvements.

Liu W, Xu J, Fu W, Wang X, Lei C, Chen Y. Evidence of stress imprinting with population‐level differences in two moss species. Ecol Evol. 2019;9:6329–6341. 10.1002/ece3.5205

REFERENCES

  1. Ahmad, P. , Abdel Latef, A. A. , Hashem, A. , Abd_Allah, E. F. , Gucel, S. , & Tran, L.‐S.‐P. (2016). Nitric oxide mitigates salt stress by regulating levels of osmolytes and antioxidant enzymes in chickpea. Frontiers in Plant Science, 7, 347 10.3389/fpls.2016.00347 [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Asensi‐Fabado, M. A. , Oliván, A. , & Munné‐Bosch, S. (2013). A comparative study of the hormonal response to high temperatures and stress reiteration in three Labiatae species. Environmental and Experimental Botany, 94(6), 57–65. [Google Scholar]
  3. Bari, R. , & Jones, J. D. G. (2009). Role of plant hormones in plant defence response. Plant Molecular Biology, 69, 473–488. [DOI] [PubMed] [Google Scholar]
  4. Beckett, R. P. (1999). Partial dehydration and ABA induce tolerance to desiccation‐induced ion leakage in the moss Atrichum androgynum . South African Journal of Botany, 65, 212–217. 10.1016/S0254-6299(15)30976-5 [DOI] [Google Scholar]
  5. Beckett, R. P. , Csintalan, Z. , & Tuba, Z. (2000). ABA treatment increases both the desiccation tolerance of photosynthesis, and non photochemical quenching in the moss Atrichum undulatum . Plant Ecology, 151, 65–71R. [Google Scholar]
  6. Beckett, R. P. , Marschall, M. , & Laufer, Z. (2005). Hardening enhances photoprotection in the moss Atrichum androgynum during rehydration by increasing fast‐ rather than slow‐relaxing quenching. Journal of Bryology, 27, 7–12. 10.1179/174328205x40536 [DOI] [Google Scholar]
  7. Beers, R. F. , & Sizer, I. W. (1952). A spectrophotometric method for measuring the breakdown of hydrogen peroxide by catalase. Journal of Biological Chemistry, 195, 133–140. [PubMed] [Google Scholar]
  8. Bhyan, S. B. , Minami, A. , Kaneko, Y. , Suzuki, S. , Arakawa, K. , Sakata, Y. , & Takezawa, D. (2012). Cold acclimation in the moss Physcomitrella patens involves abscisic acid‐dependent signaling. Journal of Plant Physiology, 169, 137–145. 10.1016/j.jplph.2011.08.004 [DOI] [PubMed] [Google Scholar]
  9. Blödner, C. , Skroppa, T. , Johnsen, Ø. , & Polle, A. (2005). Freezing tolerance in two Norway spruce (Picea abies (L.) Karst.) progenies is physiologically correlated with drought tolerance. Journal of Plant Physiology, 162, 549–558. 10.1016/j.jplph.2004.09.005 [DOI] [PubMed] [Google Scholar]
  10. Bopp, M. , & Werner, O. (1993). Abscisic acid and desiccation tolerance in mosses. Botanica Acta, 106, 103–106. [Google Scholar]
  11. Briggs, D. (1972). Population differentiation in Marchantia polymorpha L. in various lead pollution levels. Nature, 238, 166–167. 10.1038/238166a0 [DOI] [PubMed] [Google Scholar]
  12. Brinda, J. C. , Stark, L. R. , Clark, T. A. , & Greenwood, J. L. (2016). Embryos of a moss can be hardened to desiccation tolerance: Effects of rate of drying on the timeline of recovery and dehardening in Aloina ambigua (Pottiaceae). Annals of Botany, 117, 153–163. 10.1093/aob/mcv136 [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Bruce, T. J. A. , Matthes, M. C. , Napier, J. A. , & Pickett, J. A. (2007). Stressful “memories” of plants: Evidence and possible mechanisms. Plant Science, 173, 603–608. 10.1016/j.plantsci.2007.09.002 [DOI] [Google Scholar]
  14. Cao, Z. Y. , Ma, Y. N. , Mou, R. X. , Yu, S. S. , & Chen, M. X. (2015). Analysis of 17 cytokinins in rice by solid phase extraction purification and liquid chromatography‐tandem mass spectrometry. Chinese Journal of Chromatography, 33, 715–721. [DOI] [PubMed] [Google Scholar]
  15. Chambers, S. M. , & Emery, N. C. (2016). Population differentiation and countergradient variation throughout the geographic range in the fern gametophyte Vittaria appalachiana . American Journal of Botany, 103(1), 86–98. [DOI] [PubMed] [Google Scholar]
  16. Cruz de Carvalho, R. , Bernades da Silva, A. , Branquinho, C. , & Marques da Silva, J. (2015). Influence of dehydration rate on cell sucrose and water relations parameters in an inducible desiccation tolerant aquatic bryophyte. Environmental and Experimental Botany, 120, 18–22. 10.1016/j.envexpbot.2015.07.002 [DOI] [Google Scholar]
  17. Cruz de Carvalho, R. , Bernades da Silva, A. , Soares, R. , Almeida, A. M. , Coelho, A. V. , Marques da Silva, J. , & Branquinho, C. (2014). Differential proteomics of dehydration and rehydration in bryophytes: Evidence towards a common desiccation tolerance mechanism. Plant, Cell and Environment, 37, 1499–1515. [DOI] [PubMed] [Google Scholar]
  18. Cruz de Carvalho, R. , Catalá, M. , Branquinho, C. , Marques da Silva, J. , & Barreno, E. (2017). Dehydration rate determines the degree of membrane damage and desiccation tolerance in bryophytes. Physiologia Plantarum, 159, 277–289. 10.1111/ppl.12511 [DOI] [PubMed] [Google Scholar]
  19. Cvikrová, M. , Gemperlová, L. , Dobrá, J. , Martincová, O. , Prásil, I. T. , Gubis, J. , & Vanková, R. (2012). Effect of heat stress on polyamine metabolism in proline‐over‐producing tobacco plants. Plant Science, 182, 49–58. 10.1016/j.plantsci.2011.01.016 [DOI] [PubMed] [Google Scholar]
  20. De Diego, N. , Sampedro, M. C. , Barrio, R. J. , Saiz‐Fernadez, I. , Moncalean, P. , & Lacuesta, M. (2013). Solute accumulation and elastic modulus changes in six radiata pine breeds exposed to drought. Tree Physiology, 33, 69–80. [DOI] [PubMed] [Google Scholar]
  21. Deeba, F. , Pandey, A. K. , Ranjan, S. , Mishra, A. , Singh, R. , Sharma, Y. K. , … Pandey, V. (2012). Physiological and proteomic responses of cotton (Gossypium herbaceum L.) to drought stress. Plant Physiology and Biochemistry, 53, 6–18. 10.1016/j.plaphy.2012.01.002 [DOI] [PubMed] [Google Scholar]
  22. Dilks, T. J. K. , & Proctor, M. C. F. (1976). Effects of intermittent desiccation on bryophytes. Journal of Bryology, 9, 249–264. 10.1179/jbr.1976.9.2.249 [DOI] [Google Scholar]
  23. Drábková, L. Z. , Dobrev, P. I. , & Motyka, V. (2015). Phytohormone profiling across the bryophytes. PLoS ONE, 10(5), e0125411. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Gajdošová, S. , Spíchal, L. , Kamínek, M. , Hoyerová, K. , Novák, O. , Dobrev, P. I. , … Motyka, V. (2011). Distribution, biological activities, metabolism, and the conceivable function of cis-zeatin-type cytokinins in plants. Journal of Experimental Botany, 62, 2827–2840. 10.1093/jxb/erq457. [DOI] [PubMed] [Google Scholar]
  25. Ha, S. , Vankova, R. , Yamaguchi‐Shinozaki, K. , Shinozaki, K. , & Tran, L.‐S.‐P. (2012). Cytokinins: Metabolism and function in plant adaptation to environmental stresses. Trends in Plant Science, 17(3), 172–179. 10.1016/j.tplants.2011.12.005 [DOI] [PubMed] [Google Scholar]
  26. Hájek, T. , & Vicherová, E. (2014). Desiccation tolerance of Sphagnum revisited: A puzzle resolved. Plant Biology, 16, 765–773. 10.1111/plb.12126 [DOI] [PubMed] [Google Scholar]
  27. Havlová, M. , Dobrev, P. I. , Motyka, V. , Štorchová, H. , Libus, J. , Dobrá, J. , … Vanková, R. (2008). The role of cytokinins in responses to water deficit in tobacco plants over‐expressing trans‐zeatin O‐glucosyltransferase gene under 35S or SAG12 promoters. Plant, Cell and Environment, 31, 341–353. 10.1111/j.1365-3040.2007.01766.x [DOI] [PubMed] [Google Scholar]
  28. Hedderson, T. A. , & Longton, R. E. (2008). Local adaption in moss life histories: Population‐level variation and a reciprocal transplant experiment. Journal of Bryology, 30, 6329–11. 10.1179/174328208x282175 [DOI] [Google Scholar]
  29. Hellwege, M. , Dietz, K. , Volk, O. H. , & Hartung, W. (1994). Abscisic acid and the induction of desiccation tolerance in the extremely xerophilic liverwort Exormotheca holstii . Planta, 194, 525–531. 10.1007/BF00714466 [DOI] [Google Scholar]
  30. Hu, Y. R. , Jiang, L. Q. , Wang, F. , & Yu, D. Q. (2013). Jasmonate regulates the inducer of cbf expression‐C‐repeat binding factor/DRE binding factor1 cascade and freezing tolerance in Arabidopsis . The Plant Cell, 25(8), 2907–2924. 10.1105/tpc.113.112631 [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Hüve, K. , Bichele, I. , Tobias, M. , & Niinemets, Ü. (2006). Heat sensitivity of photosynthetic electron transport varies during the day due to changes in sugars and osmotic potential. Plant, Cell and Environment, 29, 212–228. 10.1111/j.1365-3040.2005.01414.x [DOI] [PubMed] [Google Scholar]
  32. Kohli, A. , Sreenivasulu, N. , Lakshmanan, P. , & Kumar, P. P. (2013). The phytohormone crosstalk paradigm takes center stage in understanding how plants respond to abiotic stresses. Plant Cell Reports, 32, 945–957. 10.1007/s00299-013-1461-y [DOI] [PubMed] [Google Scholar]
  33. Korpelainen, H. , Pohjamo, M. , & Laaka‐Lindberg, S. (2005). How efficiently does bryophyte dispersal lead to gene flow? The Journal of the Hattori Botanical Laboratory, 97, 195–205. [Google Scholar]
  34. Lázaro‐Nogal, A. , Matesanz, S. , Hallik, L. , Krasnova, A. , Traveset, A. , & Valladares, F. (2016). Population differentiation in a Mediterranean relict shrub: The potential role of local adaptation for coping with climate change. Oecologia, 180, 1075–1090. [DOI] [PubMed] [Google Scholar]
  35. Liu, B. Y. , Lei, C. Y. , Jin, J. H. , Guan, Y. Y. , Li, S. , Zhang, Y. S. , & Liu, W. Q. (2016). Physiological responses of two moss species to the combined stress of water deficit and elevated N deposition (II): Carbon and nitrogen metabolism. Ecology and Evolution, 6, 7596–7609. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Liu, B. Y. , Lei, C. Y. , Jin, J. H. , Li, S. , Zhang, Y. S. , & Liu, W. Q. (2015). Physiological responses of two moss species to the combined stress of water deficit and elevated nitrogen deposition. I secondary metabolism. International Journal of Plant Sciences, 176, 446–457. 10.1086/681023 [DOI] [Google Scholar]
  37. Liu, B. Y. , Lei, C. Y. , Shu, T. , Zhang, Y. S. , Jin, J. H. , Li, S. , & Liu, W. Q. (2015). Effects of low‐temperature stress on secondary metabolism in mosses exposed to simulated N deposition. Plant Ecology and Diversity, 83, 415–426. 10.1080/17550874.2015.1010187 [DOI] [Google Scholar]
  38. Liu, H. B. , Li, X. H. , Xiao, J. H. , & Wang, S. P. (2012). A convenient method for simultaneous quantification of multiple phytohormones and metabolites: Application in study of rice‐bacterium interaction. Plant Methods, 8, 2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Liu, W. Q. , Liu, B. Y. , Lei, C. Y. , Zhang, Y. S. , & Guo, W., (2011). Physiological responses of Pogonatum cirratum subsp. fuscatum living in different habitats to simulated nitrogen deposition. Acta Ecologica Sinica, 31, 291–297. 10.1016/j.chnaes.2011.07.007 [DOI] [Google Scholar]
  40. Mayaba, N. , Beckett, R. P. , Csintalan, Z. , & Tuba, Z. (2001). ABA increases the desiccation tolerance of photosynthesis in the afromontane understorey moss Atrichum androgynum . Annals of Botany, 88, 1093–1100. 10.1006/anbo.2001.1552 [DOI] [Google Scholar]
  41. Mittal, S. , Kumari, N. , & Sharma, V. (2012). Differential response of salt stress on Brassica juncea: Photosynthetic performance, pigment, proline, D1 and antioxidant enzymes. Plant Physiology and Biochemistry, 54, 17–26. [DOI] [PubMed] [Google Scholar]
  42. Nagao, M. , Minami, A. , Arakawa, K. , Fujikawa, S. , & Takezawa, D. (2005). Rapid degradation of starch in chloroplasts and concomitant accumulation of soluble sugars associated with ABA‐induced freezing tolerance in the moss Physcomitrella patens . Journal of Plant Physiology, 162, 169–180. 10.1016/j.jplph.2004.06.012 [DOI] [PubMed] [Google Scholar]
  43. Nikiforou, C. , & Manetas, Y. (2018). Ecological stress memory: Evidence in two out of seven species through the examination of the relationship between leaf fluctuating asymmetry and photosynthesis. Ecological Indicators, 74, 530–534. [Google Scholar]
  44. Nishiyama, R. , Watanabe, Y. , Fujita, Y. , Le, D. T. , Kojima, M. , Werner, T. , … Tran, L.‐S. (2011). Analysis of cytokinin mutants and regulation of cytokinin metabolic genes reveals important regulatory roles of cytokinins in drought, salt and abscisic acid responses, and abscisic acid biosynthesis. The Plant Cell, 23, 2169–2183. 10.1105/tpc.111.087395 [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Peleg, Z. , & Blumwald, E. (2011). Hormone balance and abiotic stress tolerance in crop plants. Current Opinion in Plant Biology, 14, 290–295. 10.1016/j.pbi.2011.02.001 [DOI] [PubMed] [Google Scholar]
  46. Pohjamo, M. , Korpelainen, H. , & Kalinauskaitė, N. (2008). Restricted gene flow in the clonal hepatic Trichocolea tomentella in fragmented landscapes. Biological Conservation, 141, 1204–1217. 10.1016/j.biocon.2008.02.016 [DOI] [Google Scholar]
  47. Schonbeck, M. W. , & Bewley, J. D. (1981a). Responses of the moss Tortula ruralis to desiccation treatments. I. Effects of minimum water content and rates of dehydration and rehydration. Canadian Journal of Botany, 59, 2698–2706. [Google Scholar]
  48. Schonbeck, M. W. , & Bewley, J. D. (1981b). Responses of the moss Tortula ruralis to desiccation treatments. II. Variations in desiccation tolerance. Canadian Journal of Botany, 59, 2707–2712. [Google Scholar]
  49. Shanghai Institute of Plant Physiology Chinese Academy of Sciences (SIPP) (1999). Experimental Guidance for Modern Plant Physiology. Beijing, China: Science Press. (in Chinese). [Google Scholar]
  50. Singh, B. , & Usha, K. (2003). Salicylic acid induced physiological and biochemical changes in wheat seedlings under water stress. Plant Growth Regulation, 39, 137–141. [Google Scholar]
  51. Snäll, T. , Ribeiro, P. J. Jr , & Rydin, H. (2003). Spatial occurrence and colonisations in patch‐tracking metapopulations: Local conditions versus dispersal. Oikos, 103, 566–578. [Google Scholar]
  52. Sofo, A. , Dichio, B. , Xiloyannis, C. , & Masia, A. (2004). Effects of different irradiance levels on some antioxidant enzymes and on malondialdehyde content during rewatering in olive tree. Plant Science, 166, 293–302. 10.1016/j.plantsci.2003.09.018 [DOI] [Google Scholar]
  53. Stark, L. R. , Greenwood, J. L. , Brinda, J. C. , & Oliver, M. J. (2014). Physiological history may mask the inherent inducible desiccation tolerance strategy of the desert moss Crossidium crassinerve . Plant Biology (Stuttgart, Germany), 16, 935–946. 10.1111/plb.12140 [DOI] [PubMed] [Google Scholar]
  54. Troll, W. , & Lindsley, J. (1955). A photometric method for the determination of proline. Journal of Biological Chemistry, 215, 655–660. [PubMed] [Google Scholar]
  55. Verma, V. , Ravindran, P. , & Kumar, P. P. (2016). Plant hormone‐mediated regulation of stress responses. BMC Plant Biology, 16, 86. [DOI] [PMC free article] [PubMed] [Google Scholar]
  56. Verslues, P. E. (2016). ABA and cytokinins: Challenge and opportunity for plant stress research. Plant Molecular Biology, 91, 629–640. [DOI] [PubMed] [Google Scholar]
  57. Walter, J. , Jentsch, A. , Beierkuhnlein, C. , & Kreyling, J. (2013). Ecological stress memory and cross stress tolerance in plants in the face of climate extremes. Environmental and Experimental Botany, 94, 3–8. 10.1016/j.envexpbot.2012.02.009 [DOI] [Google Scholar]
  58. Wang, L. , Fan, L. , Loescher, W. , Duan, W. , Liu, G. , Cheng, J. , … Li, S.‐H. (2010). Salicylic acid alleviates decreases in photosynthesis under heat stress and accelerates recovery in grapevine leaves. BMC Plant Biology, 10, 34–34. 10.1186/1471-2229-10-34 [DOI] [PMC free article] [PubMed] [Google Scholar]
  59. Wang, X. K. , & Huang, J. L. (2015). Principles and techniques of plant physiological biochemical experiment (3rd ed.). Beijing, China: Higher Education Press. (in Chinese). [Google Scholar]
  60. Wang, Y. Y. , Zhu, Y. Q. , & Wang, Y. F. (2012). Differences in spatial genetic structure and diversity in two mosses with different dispersal strategies in a fragmented landscape. Journal of Bryology, 34, 9–16. 10.1179/1743282011Y.0000000035 [DOI] [Google Scholar]
  61. Werner, O. , Ros Espín, R. M. , Bopp, M. , & Atzorn, R. (1991). Abscisic‐acid‐induced drought tolerance in Funaria hygrometrica Hedw. Planta, 186, 99–103. 10.1007/BF00201503 [DOI] [PubMed] [Google Scholar]
  62. Xiao, L. , Yobi, A. , Koster, K. L. , He, Y. , & Oliver, M. J. (2018). Desiccation tolerance in Physcomitrella patens: Rate of dehydration and the involvement of endogenous abscisic acid (ABA). Plant, Cell and Environment, 41, 275–284. [DOI] [PubMed] [Google Scholar]
  63. Ye, B. , & Gressel, J. (2000). Transient, oxidant‐induced antioxidant transcript and enzyme levels correlate with greater oxidant‐resistance in paraquat‐resistant Conyza bonariensis . Planta, 211, 50–61. 10.1007/s004250000257 [DOI] [PubMed] [Google Scholar]
  64. Yu, Q. , & Rengel, Z. (1999). Micronutrient deficiency influences plant growth and activities of superoxide dismutases in narrow leafed lupins. Annals of Botany, 83, 175–182. 10.1006/anbo.1998.0811 [DOI] [Google Scholar]
  65. Zhao, X. , Shi, Y. , Liu, Y. , Jia, R.‐L. , & Li, X.‐R. (2015). Osmotic adjustment of soil biocrust mosses in response to desiccation stress. Pedosphere, 25(3), 459–467. [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

The data of ROS, osmolytes, and phytohormones: Dryad https://doi.org/10.5061/dryad.833qr19.

Articles from Ecology and Evolution are provided here courtesy of Wiley

RESOURCES