Table 1.
The effects of different environmental stresses on the content and accumulation of secondary metabolites in various plant species.
| Plant Species | Abiotic Stress | Secondary Metabolite and Nature of Response | Reference |
|---|---|---|---|
|
Ocimum basilicum (common basil) |
AgNO3 | The highest values of linalool and estragole compared with the control culture were obtained as 4.37 μg/g DW (25 μM treatment) and 3.30 μg/g DW (5 μM treatment), respectively. | [43] |
|
Chrysanthemum morifoilum (garden mum) |
Water | Anthocyanin content was observed to show an increasing trend by 1.71 and 3.5 times on days 7 and 5 of the stress period, respectively. | [44] |
|
Olea europaea (common olive) cultivars |
NaCl | Under 60 and 120 mM NaCl, the content of kaempferol in old leaves of Frantoio increased by three times (25.1 and 27.4 g g−1 FW, respectively). However, in Leccino, kaempferol remains unchanged at 60 mM NaCl and reduced 16 times (0.5 g g−1 FW) at 120 mM NaCl, when compared to control. Similarly, quercetin did not change up to 60 mM NaCl in both cultivars, while at the highest NaCl treatment (120 mM), it slightly increased in Frantoio. | [45] |
|
Lycopersicon esculentum (garden tomato) |
Pb | The treatment of Pb enhances the production of phenol, flavonoid, and anthocyanin content by 79.25%, 47.73%, and 58.25%, respectively, at 0.75 mM concentration. | [46] |
|
Artemisia annua L. (sweet sagewort) |
UV-B | UV-B-treated plants observed significant induction of 92 and 100% in total phenolic and flavonoid content after 3 h, respectively. However, artemisinin observed concentration up to 100%. | [47] |
| Citrus genotypes | Drought and heat stress | In Carrizo, impact of heat stress on secondary metabolite composition was 26.3%, whereas water stress had a lower contribution 18.8%. In Cleopatra, however, both heat and water stress influenced the secondary metabolite accumulation (21.1%), although the stress combination had a stronger contribution (26.2%). | [48] |
| Genista tinctoria (dyer’s greenweed) | UV radiation | The highest genistin content (3.03%) was demonstrated after 300 s of UV 254 nm treatment, followed by 2.06% accumulation after 120 s of UV 366 nm radiation. Similarly, 0.16–0.17% genistein content was observed after UV 254 nm treatment. | [49] |
| Mentha pulegium L. (pennyroyal) | Drought | The moderate and severe drought stress treatments increased TPC (17.2 and 30.3%, respectively) and TFC (35.9 and 33.7%, respectively). | [50] |
| Salvia dolomitica Codd (dolomite sage) | Drought | These total phenols and flavonoids were substantially reduced by moderate and severe drought stress compared with control (305.2, 53.2, and 20.5 mg GAE g−1, 105.7, 17.1, and 5.3 mg g−1, respectively). | [51] |
| Brassica oleracea L. convar. acephala (DC) Alef, var. sabellica L. (cabbage) | Drought | The content of proline and phytol in drought-stressed plants when compared to well-watered plants showed an increased trend of more than 22%, with values of 7.56 to 22.7 mg/plant for proline, respectively, and 22.1 to 35.6 mg/plant for phytol, respectively. | [52] |
| Cotton genotypes | Drought and Salinity | In Zhongmian 23, TPC increased significantly under drought and/or salinity compared to their controls, while under salinity, it remained unaffected at 10% SMC. However, in Zhongmian 41, TPC was significantly increased under D + S relative to control and remained unchanged under drought, but it was significantly decreased under salinity when compared to control. Both drought and/or salinity stress increased TFC content. However, under salinity, it decreased in Zhongmian 23 and increased in Zhongmian 41 at 10% SMC, while at 4% SMC it remained unaffected compared to control. | [53] |
| Carthamus tinctorius L. (safflower) | Salinity | Significant increase of 34% in TPC, 13% in TFC, and 12% in TFL was observed in salinity-stressed plants when compared to nonstressed plants. | [54] |
| Solanum nigrum L. (black nightshade) | NaCl | Significant increases were observed in both lutein and β-carotene at 100 mM NaCl, while at 50 and 150 mM NaCl, both compounds showed reduced accumulation. Quercetin levels increased 2.6-fold compared to quercetin 3-β-D-glucoside at 0 and 50 mM NaCl treatments, whereas they were the same for the 100 mM treatment and 2-fold lower at 150 mM NaCl treatment. | [55] |
| Camellia japonica cultivars (Japanese camellia) | Temp. | In ‘Jiangxue’, the content of palmitic acid, stearic acid, and oleic acid gradually decreased during cold treament, while α-linolenic acid increased significantly. Similar tendencies were found in ‘Desire’ and ‘Nuccio’s Bella Rossa’, but the changes were not as significant as in ‘Jiangxue’. | [56] |
| Musa spp. (banana) | Temp. | The TPC of Simili radjah increased 2.9-fold, from 6.3 (26 °C) to 18.5 ng/g GAE (20 °C), whereas it increased 4.8-fold from 8.6 (26 °C) to 41.6 ng/g GAE (20 °C) for Dole. | [57] |
| Scutellaria lateriflora (mad dog skullcap) | Light | The accumulation of baicalin was promoted by blue light, 0.96–2.00 times higher than under white light. Flavonoids showed 0.93–1.54 times accumulation in blue light than under white light. However, 3,4-dihydroxyphenylacetic acid observed the highest concentration of (33.56 mg 100 g−1 DW) in the presence of white light. | [58] |
|
Silybum marianum L. (milk thistle) |
Light | Under red light, silymarin content (18.67 mg/g DW) was almost double compared to control (9.17 mg/g DW). Conversely, taxifolin accumulation (0.480 mg/g DW) was found to be maximum under continuous white light, which was almost eightfold higher than control (0.063 mg/g DW). | [59] |
|
Rhododendron tomentosum (marsh Labrador tea) |
Cu and Ni | About a twofold increase in pcymene and sabinene was observed in Cu- and Ni-treated plants compared with control. Pcymene and sabinene contents were about 23.0% and 17.7% vs. 6.9% (control), respectively; and 5.4% and 3.0% vs. 1.7% (control), respectively. On the other hand, δ-cadinene was decreased by 1.0% and 1.1% vs. 4.1% (control), respectively, in the total level of sesquiterpene hydrocarbons. | [60] |
| Corylus avellana L. (common hazel) | Al | Extracellular taxol content showed an upward trend at 100 µM of Al treatment and was 38-fold higher than that of the control medium. However, cell-associated taxol content at 50 and 100 µM of Al concentration was enhanced by 11.4- and 8.3-fold, respectively, compared to control cells. | [61] |
| Linum usitatissimum L. (flax) | UV + photoperiod | Under UV + dark and UV + photoperiod, 1.12- and 2.82-fold enhancement in TPP was noted, respectively, in response to 3.6 kJ/m2 of UV-C radiations. However, at similar conditions, TFP showed 1.42- and 2.94-fold enhancement compared to their respective controls. | [62] |
|
Duboisia Species (corkwood) |
Light and temperature | Scopolamineproduction showed a negative trend by increased light intensity up to 350 μmol/m2 × s, light exposure up to 24 h/d, and temperature (28 °C). | [63] |
TPC—total phenolic content, TFC—total flavonoid content, TFP—total flavonoid production, TPP—total phenolic production, SMC—soil moisture content, TFL—total flavonols, DW—dry weight, FW—fresh weight, D—drought, S—salinity.