Skip to main content
NCBI home page
Plant Biotechnology logoLink to Plant Biotechnology
. 2022 Mar 25;39(1):73–78. doi: 10.5511/plantbiotechnology.21.1103a

Brassinosteroids are required for efficient root tip regeneration in Arabidopsis

Naoki Takahashi 1,*, Masaaki Umeda 1
PMCID: PMC9200090  PMID: 35800959

Abstract

Compared with other organisms, plants have an extraordinary capacity for self-repair. Even if the entire tissues, including the stem cells, are resected, most plant species are able to completely regenerate whole tissues. However, the mechanism by which plants efficiently regenerate the stem cell niche during tissue reorganization is still largely unknown. Here, we found that the signaling mediated by plant steroid hormones brassinosteroids is activated during stem cell formation after root tip excision in Arabidopsis. Treatment with brassinazole, an inhibitor of brassinosteroid biosynthesis, delayed the recovery of stem cell niche after root tip excision. Regeneration of root tip after resection was also delayed in a brassinosteroid receptor mutant. Therefore, we propose that brassinosteroids participate in efficient root tip regeneration, thereby enabling efficient tissue regeneration to ensure continuous root growth after resection.

Keywords: Arabidopsis, brassinosteroid, regeneration, stem cell niche

Introduction

Plants have a high capacity to regenerate their organs and tissues, thereby enabling their continuous growth, even if tissues are resected. In Arabidopsis root tips, excision of the root meristem, which includes the stem cell niche (SCN) composed of quiescent center (QC) cells and surrounding stem cells, stimulates regeneration, and the root tip is completely reformed within three to four days of excision (Sena et al. 2009). This regeneration process requires organization of the SCN from the remaining meristematic cells (Efroni et al. 2016; Matosevich et al. 2020; Sena et al. 2009).

Several transcription factors have been reported to play important roles in root tip regeneration in Arabidopsis. ETHYLENE RESPONSE FACTOR 115 (ERF115), a member of the APETALA2 (AP2) family transcription factors, was found to be rapidly induced after excision of the root tip and is required for regeneration. This is evident from the fact that impaired ERF115 activity causes a lack of root tip regeneration (Heyman et al. 2016; Johnson et al. 2018; Zhou et al. 2019). WOUNDING INDUCED DEDIFFERENTIATION 1 (WIND1), another member of the AP2 family transcription factors, is also shown to play a role in cellular dedifferentiation during the regeneration process (Iwase et al. 2011). Additionally, several phytohormones have been shown to participate in root tip regeneration. The phytohormone auxin plays a crucial role in tip regeneration, and treatment with auxin biosynthesis or transport inhibitors severely suppresses root tip regeneration (Efroni et al. 2016; Matosevich et al. 2020; Sena et al. 2009). Furthermore, auxin biosynthesis at the excision site is necessary for the progression of regeneration (Matosevich et al. 2020). The signaling interaction between auxin and cytokinin is important for providing positional information for SCN formation during root tip regeneration (Efroni et al. 2016). Jasmonic acid is also required for root tip regeneration, triggering ERF115 expression (Zhou et al. 2019). However, it is still unclear whether these transcription factors and phytohormones are sufficient for complete root tip regeneration and organization of the SCN after root tip excision.

Plant growth and patterning processes are regulated by the interaction between various phytohormones (Depuydt and Hardtke 2011). A class of plant steroid hormone brassinosteroids is involved in cell division, elongation, differentiation, and stress responses (Clouse and Sasse 1998), and the signaling cascades have been shown to crosstalk with that of auxin in various cellular processes (Nemhauser et al. 2004). Brassinosteroids are perceived by BRASSINOSTEROID INSENSITIVE 1 (BRI1) and its homologs BRI1-LIKE 1 and BRI1-LIKE 3 (BRL1 and BRL3), which are members of the leucine-rich repeat receptor-like kinase (LRR-RLK) family (Caño-Delgado et al. 2004; Li and Chory 1997). When these receptors bind brassinosteroids, they heterodimerize with SERK3/BRI1 ASSOCIATED KINASE1 (BAK1), initiating an intracellular phosphorylation relay cascade (Li et al. 2002). This cascade promotes the activity and stability of plant-specific transcription factors BRASSINAZOLE RESISTANT 1 (BZR1) and BRI1-EMS-SUPPRESSOR 1 (BES1), which in turn control the transcription of brassinosteroid responsive genes (Wang et al. 2002; Yin et al. 2005). The signaling pathways between auxin and brassinosteroids is integrated downstream from BES1 and AUX/IAA proteins, the regulatory factors acting downstream of each hormone (Nemhauser et al. 2004). However, the role of brassinosteroids in tissue regeneration remains largely unknown.

In this study, we found that brassinosteroid signaling is activated in stem cell formation after root tip excision in Arabidopsis. Since the inhibition of brassinosteroid biosynthesis delayed the recovery of SCN in root tip, we propose that brassinosteroids are required for the efficient root tip regeneration in Arabidopsis.

Materials and methods

Plant materials and growth conditions

Arabidopsis thaliana (ecotype Columbia-0) plants were grown vertically under continuous light conditions at 22°C on Murashige and Skoog (MS) plates [0.5×MS salts, 0.5 g l−1 2-(N-morpholino)ethanesulfonic acid (MES), 1% sucrose, and 1.2% phytoagar (pH 5.7)]. pBRZ1:BZR1-YFP (Chaiwanon and Wang 2015), pWOX5:NLS-GFP (Waki et al. 2011), pBRI1:BRI1-GFP (Fàbregas et al. 2013), pBRL1:BRL1-YFP (Fàbregas et al. 2013), pBRL3:BRL3-YFP (Fàbregas et al. 2013), and bri1 brl1 brl3 bak1 (Fàbregas et al. 2018) were described previously.

Root tip excision assay

Root tips were cut according to previously published protocols (Sena et al. 2009). In brief, root tips of seven-day-old seedlings grown on MS plates were cut around 130 µm from the outermost layer of columella cells (red line in Figure 1A) by hand under a stereomicroscope using a sterile needle, resulting in the removal of the SCN and root cap including the columella and most of the lateral root cap. Seedlings were transferred back to MS plates and grown for one to five days. For brassinazole treatment, seedlings after root tip excision were transferred to MS plates supplemented with 3 µM brassinazole and were grown for the indicated number of days.

Figure 1. Brassinosteroid signaling is activated during SCN formation after root tip excision. (A) Schematic representation of Arabidopsis root tip with quiescent center (QC) and stem cells. The red dotted line marks the cut site used in this study. (B) Activity of brassinosteroid signal after root tip excision. Root tips of seven-day-old pBZR1:BZR1-YFP seedlings were cut, and seedlings were transferred to MS plates. Plants were additionally grown for one to five days. YFP fluorescence (green) counterstained with SR2200 (white) was observed before and after root tip excision. Magnified images of the areas marked by yellow boxes (I-VIII) are shown on the bottom. Bars=50 µm. (C) The nuclear-to-cytoplasmic (N/C) ratio of BZR1-YFP in stem cell formation after root tip excision. YFP fluorescence in nucleus and cytoplasm was measured in areas indicated by yellow boxes (B), and the N/C ratio was calculated. Data are presented as mean±SD (n>5). Bars with different letters are significantly different each other (Student’s t-test: p<0.05).

Figure 1. Brassinosteroid signaling is activated during SCN formation after root tip excision. (A) Schematic representation of Arabidopsis root tip with quiescent center (QC) and stem cells. The red dotted line marks the cut site used in this study. (B) Activity of brassinosteroid signal after root tip excision. Root tips of seven-day-old pBZR1:BZR1-YFP seedlings were cut, and seedlings were transferred to MS plates. Plants were additionally grown for one to five days. YFP fluorescence (green) counterstained with SR2200 (white) was observed before and after root tip excision. Magnified images of the areas marked by yellow boxes (I-VIII) are shown on the bottom. Bars=50 µm. (C) The nuclear-to-cytoplasmic (N/C) ratio of BZR1-YFP in stem cell formation after root tip excision. YFP fluorescence in nucleus and cytoplasm was measured in areas indicated by yellow boxes (B), and the N/C ratio was calculated. Data are presented as mean±SD (n>5). Bars with different letters are significantly different each other (Student’s t-test: p<0.05).

Open in a new tab

Microscopic observation and measurement of fluorescence

Seedlings were soaked in SR2200 solution [4% paraformaldehyde in PBS (pH 7.4) and 0.1% SCRI Renaissance 2200 (Renaissance Chemicals)] for 12 h at 4°C. Samples were washed with PBS and submerged in ClearSee solution [10% xylitol, 15% sodium deoxycholate, and 25% urea] until the root became transparent. For the protein marker lines BRI1-GFP, BRL1-YFP, and BRL3-YFP, roots were stained with 10 µM propidium iodide solution for 3 min at room temperature. Root tips were subsequently observed under a confocal laser scanning microscope (Olympus, FluoView FV3000), and GFP and YFP fluorescence were measured using Fiji image analysis software (http://fiji.sc). To calculate the ratio of nuclear-to-cytoplasm signal of BZR1-YFP, the amount of YFP fluorescence in the nucleus and cytoplasm of each cell was quantified using Fiji software, respectively, and the signal value of the nucleus divided by that of the cytoplasm was calculated.

Results

Brassinosteroid signaling is activated during SCN formation after root tip excision

To examine the possibility that brassinosteroids participate in root tip regeneration in Arabidopsis, we initially monitored brassinosteroid signaling in root tips after tip excision. Brassinosteroid signaling has been shown to increase the nuclear localization of BZR1 protein, while BZR1 localizes to the cytoplasm when brassinosteroid signal is low (Chaiwanon and Wang 2015). Thus, the BZR1 nuclear-to-cytoplasm ratio reflects brassinosteroid signaling activity (Chaiwanon and Wang 2015). Root tips of seven-day-old pBZR1:BZR1-YFP seedlings were excised around 130 µm from the outermost layer of columella cells (Figure 1A), and YFP fluorescence was observed for five days after root tip excision. pBZR1:BZR1-YFP contains a construct harboring the 1 kb promoter and coding region that are fused to YFP (Chaiwanon and Wang 2015). When we observed the BZR1-YFP around the SCN (with the QC and surrounding stem cells located approximately 70 µm from the outermost layer of columella cells: Figure 1B; I) of uncut roots, the YFP signal was found to be accumulated mainly in the cytoplasm, indicating that brassinosteroid signaling activity is low in the SCN (Figure 1B, C; I). In contrast, in the area above the excision site, wherein the stele located approximately 160 µm from the outermost layer of columella cells (Figure 1B; II and III), nuclear BZR1 signals showed an increase as compared to those in the SCN (Figure 1B, C; I–III). This suggests that brassinosteroid signaling is active in the meristematic region. Interestingly, one to two days after root tip excision, a strong nuclear-localized BZR1 signal was observed around the SCN (Figure 1B; IV and V). Quantification of the nuclear and cytoplasmic BZR1-YFP signals around the regions revealed that one to two days after root tip excision, a higher BZR1 nuclear-to-cytoplasm ratio was detected in the SCN as compared to that in uncut roots (Figure 1C; IV and V). Note that the gene expression of BZR1 was not remarkably changed during early root tip regeneration [eFP Browser, http://bar.utoronto.ca/efp/cgi-bin/efpWeb.cgi (Sena et al. 2009; Winter et al. 2007)] (Supplementary Figure S1). After three days, the ratio gradually decreased, and it reached the level of that in the SCN before excision after five days (Figure 1B, C; VI to VIII). These results suggest that brassinosteroid signaling is temporarily activated during stem cell formation after root tip excision.

Brassinosteroid biosynthesis is required for efficient SCN regeneration after root tip excision

To examine whether brassinosteroids are involved in SCN regeneration after root tip excision, we tested the response of root tips to brassinazole, an inhibitor of brassinosteroid biosynthesis (Min et al. 1999) in SCN regeneration. The root tips of seven-day-old pWOX5:NLS-GFP, which is the transcriptional marker line that mark the QC cells in the root SCN (Waki et al. 2011) were cut and transferred onto MS plates with or without 3 µM brassinazole. As previously reported (Sena et al. 2009), under control conditions, pWOX5:NLS-GFP was ectopically expressed in a small number of endodermal and cortex cells one day after root tip excision, and the signal was also observed around de novo stem cell formation after two days (Figure 2A; 1 and 2 dpc). After three days, it was found that WOX5 expression was restricted to the SCN (Figure 2A; 3 dpc), indicating that the SCN is almost recovered after three days of root tip excision. In roots treated with brassinazole, pWOX5:NLS-GFP was expressed in some endodermal and cortex cells one to two days after root tip excision (Figure 2B; 1 and 2 dpc). After three to four days, GFP expression was observed to a cup-shaped domain encompassing the endodermal and cortex cell files and the SCN (Figure 2B; 3 and 4 dpc). After five days, GFP fluorescence was detected only in the SCN (Figure 2B; 5 dpc), indicating that the morphology of SCN is almost recovered in the brassinazole-treated roots after five days. These results suggest that brassinosteroid biosynthesis is required for efficient SCN regeneration after root tip excision.

Figure 2. Brassinosteroid biosynthesis is required for efficient SCN regeneration after root tip excision. (A, B) Brassinazole response of the QC cell-specific reporter pWOX5:NLS-GFP after root tip excision. Root tips of seven-day-old pWOX5:NLS-GFP were cut, and plants were transferred onto MS plates supplemented with (B) or without (A) 3 µM brassinazole. Plants were further grown for one to five days. GFP fluorescence (green) counterstained with SR2200 (white) was observed. The numbers in the photos indicate the number of plants with similar expression patterns as in the photo/total number of plants observed. Magnified images of the areas marked by yellow boxes are shown below. Bars=50 µm.

Figure 2. Brassinosteroid biosynthesis is required for efficient SCN regeneration after root tip excision. (A, B) Brassinazole response of the QC cell-specific reporter pWOX5:NLS-GFP after root tip excision. Root tips of seven-day-old pWOX5:NLS-GFP were cut, and plants were transferred onto MS plates supplemented with (B) or without (A) 3 µM brassinazole. Plants were further grown for one to five days. GFP fluorescence (green) counterstained with SR2200 (white) was observed. The numbers in the photos indicate the number of plants with similar expression patterns as in the photo/total number of plants observed. Magnified images of the areas marked by yellow boxes are shown below. Bars=50 µm.

Open in a new tab

Brassinosteroid signaling promotes root tip regeneration after root tip excision

Next, we examined whether brassinosteroid signaling is required for SCN regeneration. When we analyzed the localization and accumulation of the brassinosteroid receptors BRI1, BRL1, and BRL3 proteins using reporter lines that contained the full-length genomic sequences fused to GFP or YFP under the control of the 2 kb promoters (pBRI1:BRI1-GFP, pBRL1:BRL1-YFP, and pBRL3:BRL3-YFP) (Fàbregas et al. 2013), BRI1-GFP was detected in the entire root tip, excluding the columella cells, whereas BRL1-YFP and BRL3-YFP were present in the SCN before and after root tip excision (Figure 3). The gene expression of BRI1, BRL1 and BRL3 was not changed notably during early root tip regeneration (Sena et al. 2009; Winter et al. 2007) (Supplementary Figure S1). Therefore, we observed the phenotype of the root tip regeneration after root tip excision of the bri1 brl1 brl3 bak1 quadruple loss-of-function mutant, which is insensitive to brassinolide, an active brassinosteroid (Fàbregas et al. 2018). Root tips of seven-day-old bri1 brl1 brl3 bak1 seedlings were cut, and the progression of root tip regeneration was observed. As root tip regeneration progresses, the number of cells between the cortex cells closest to the root tip gradually decreases (Sena et al. 2009). Therefore, to assess whether root tip is regenerated after root tip excision, the cells in the cortex cell layer closest to the root tip (marked with * in Figure 4A, B) were connected by a straight line (yellow dotted lines in Figure 4A, B), and the number of cells that intersected the line was counted. The results showed that one day after root tip excision, the number of cells intersecting the line was higher in the excised root tips than that in the uncut roots in wild-type plants (WT) (Figure 4A, C; uncut and 1 dpc). After two days, cell number gradually decreased (Figure 4A, C; 2 dpc), and it reached the number that had been counted before root tip excision after three days (Figure 4A, C; 3 dpc). These results indicate that the root tip is almost regenerated after three days in excised WT root tips. In contrast, three and four days after excision, the number of cells intersecting the line in the excised root tips of the bri1 brl1 brl3 bak1 mutant was higher than that in the uncut roots (Figure 4B, C; 3 and 4 dpc). After five days, the cell number was not significantly different from that in uncut roots of the mutant (Figure 4; 5 dpc), indicating that root tip regeneration was delayed in the brassinosteroid receptor mutant compared with that in WT. These results suggest that brassinosteroid signaling is involved in efficient root tip regeneration after root tip excision.

Figure 3. Brassinosteroid receptors are accumulated in the SCN. Accumulation of BRI1-GFP, BRL1-YFP, and BRL3-YFP after root tip excision. Root tips of seven-day-old pBRI1:BRI1-GFP, pBRL1:BRL1-YFP, and pBRL3:BRL3-YFP were excised. Seedlings were transferred onto MS plates and grown for one to five days. GFP or YFP fluorescence (green) was observed after counterstaining with propidium iodide (red). Bar=50 µm.

Figure 3. Brassinosteroid receptors are accumulated in the SCN. Accumulation of BRI1-GFP, BRL1-YFP, and BRL3-YFP after root tip excision. Root tips of seven-day-old pBRI1:BRI1-GFP, pBRL1:BRL1-YFP, and pBRL3:BRL3-YFP were excised. Seedlings were transferred onto MS plates and grown for one to five days. GFP or YFP fluorescence (green) was observed after counterstaining with propidium iodide (red). Bar=50 µm.

Open in a new tab

Figure 4. Regeneration of root tip is delayed in bri1 brl1 brl3 bak1. (A, B) Root tip regeneration in bri1 brl1 brl3 bak1 mutant. Root tips of seven-day-old WT (A) and bri1 brl1 brl3 bak1 (B) seedlings were cut. Plants were transferred onto MS plates and were further grown for one to five days. Root tips were observed after staining with SR2200 (white). Magnified images of the areas marked by yellow boxes are shown below. Cortex cell layer is highlighted in red, and asterisks (*) indicate cortex cells closest to the root tip. Straight yellow dotted lines are shown passing through the cortex cells closest to the root tip. Bars=50 µm. (C) Recovery of root tip in bri1 brl1 brl3 bak1. The number of cells which intersected the yellow dotted line shown in (A) and (B) was counted. Data are presented as mean±SD (n>11). Bars with different letters are significantly different from each other (Student’s t-test: p<0.05).

Figure 4. Regeneration of root tip is delayed in bri1 brl1 brl3 bak1. (A, B) Root tip regeneration in bri1 brl1 brl3 bak1 mutant. Root tips of seven-day-old WT (A) and bri1 brl1 brl3 bak1 (B) seedlings were cut. Plants were transferred onto MS plates and were further grown for one to five days. Root tips were observed after staining with SR2200 (white). Magnified images of the areas marked by yellow boxes are shown below. Cortex cell layer is highlighted in red, and asterisks (*) indicate cortex cells closest to the root tip. Straight yellow dotted lines are shown passing through the cortex cells closest to the root tip. Bars=50 µm. (C) Recovery of root tip in bri1 brl1 brl3 bak1. The number of cells which intersected the yellow dotted line shown in (A) and (B) was counted. Data are presented as mean±SD (n>11). Bars with different letters are significantly different from each other (Student’s t-test: p<0.05).

Open in a new tab

Discussion

In this study, we found that brassinosteroid signaling was activated during SCN formation after root tip excision (Figure 1) and that brassinosteroid biosynthesis and signaling are involved in efficient root tip regeneration (Figure 2). Previously, it was shown that the expression of DWARF4 (Choe et al. 1998), a rate-limiting enzyme for brassinosteroid biosynthesis, is rapidly induced after root tip excision (Sena et al. 2009). In contrast, BAS1/CYP734A1 (Turk et al. 2005), which is a major brassinosteroid inactivating enzyme, is repressed after root tip excision (Sena et al. 2009). These observations suggest that endogenous active brassinosteroid levels are increased after root tip excision. Therefore, although root excision may activate the brassinosteroid signaling pathway, it is possible that accumulation of endogenous brassinosteroids stimulates activation of brassinosteroid signaling during SCN formation, thereby promoting efficient root tip regeneration.

It has previously been shown that the transcription of several auxin biosynthesis genes, including TAA1, YUCCA3, and YUCCA9, is rapidly upregulated above the cut site, and treatment with the auxin biosynthesis inhibitor L-kynurenin leads to loss of regeneration capacity (Matosevich et al. 2020). Additionally, the blockage of auxin transport using the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) causes failure of SCN regeneration during root tip regeneration (Sena et al. 2009). These results suggest that proper auxin level and distribution are important for the regeneration of the SCN after root tip excision. In this study, we found that inhibition of brassinosteroid biosynthesis using brassinazole delayed the recovery of SCN after root tip excision (Figure 2). Additionally, the WOX5 was expressed to a cup-shaped domain of endodermal and cortex cell files three to four days post excision, respectively (Figure 2B). Previous studies have shown that treatment with NPA alters the cell fate by disrupting auxin distribution, resulting in a cup-shaped expression of WOX5 in the root tip (Sabatini et al. 1999), similar to that observed with the brassinazole treatment. Brassinosteroids enhance the expression of auxin efflux carriers such as PIN-FORMEDs (PINs) (Bao et al. 2004). Therefore, it is probable that brassinosteroids may be involved in the reestablishment of local auxin maxima around the SCN after root tip excision. Previous studies have suggested that the interaction between auxin and cytokinin sets up positional information for SCN formation after root tip excision (Efroni et al. 2016). Similarly, brassinosteroids have been shown to crosstalk with auxin and cytokinin in plant growth and development (Saini et al. 2015), implying that another layer of regulation may be involved in auxin-cytokinin-mediated SCN formation during root tip regeneration. Further studies will deepen our understanding of how plants accomplish tissue regeneration through the spatiotemporal regulation of hormonal activities after tissue resection.

Acknowledgments

We thank Ana I. Caño-Delgado, Keiji Nakajima and the Nottingham Arabidopsis Stock Centre for providing Arabidopsis mutants and transgenic plants. This work was supported by MEXT KAKENHI (Grant Numbers 17H06470 and 17H06477) and JSPS KAKENHI (Grant Numbers 19K06708 and 21H04715).

Abbreviations

AP2

APETALA2

BAK1

BRI1 ASSOCIATED KINASE1

BES1

BRI1-EMS-SUPPRESSOR 1

BRI1

BRASSINOSTEROID INSENSITIVE 1

BRL1

BRI1-LIKE 1

BRL3

BRI1-LIKE 3

BZR1

BRASSINAZOLE RESISTANT 1

ERF115

ETHYLENE RESPONSE FACTOR 115

LRR-RLK

leucine-rich repeat receptor-like kinase

MES

2-(N-morpholino)ethanesulfonic acid

MS

Murashige and Skoog

NPA

N-1-naphthylphthalamic acid

PIN

PIN-FORMED

QC

quiescent center

SCN

stem cell niche

WIND1

WOUNDING INDUCED DEDIFFERENTIATION 1

Supplementary Data

Supplementary Data

References

  1. Bao F, Shen J, Brady SR, Muday GK, Asami T, Yang Z (2004) Brassinosteroids interact with auxin to promote lateral root development in Arabidopsis. Plant Physiol 134: 1624–1631 [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Caño-Delgado A, Yin Y, Yu C, Vafeados D, Mora-García S, Cheng JC, Nam KH, Li J, Chory J (2004) BRL1 and BRL3 are novel brassinosteroid receptors that function in vascular differentiation in Arabidopsis. Development 131: 5341–5351 [DOI] [PubMed] [Google Scholar]
  3. Chaiwanon J, Wang ZY (2015) Spatiotemporal brassinosteroid signaling and antagonism with auxin pattern stem cell dynamics in Arabidopsis roots. Curr Biol 25: 1031–1042 [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Choe S, Dilkes BP, Fujioka S, Takatsuto S, Sakurai A, Feldmann KA (1998) The DWF4 gene of Arabidopsis encodes a cytochrome P450 that mediates multiple 22alpha-hydroxylation steps in brassinosteroid biosynthesis. Plant Cell 10: 231–243 [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Clouse SD, Sasse JM (1998) BRASSINOSTEROIDS: Essential regulators of plant growth and development. Annu Rev Plant Physiol Plant Mol Biol 49: 427–451 [DOI] [PubMed] [Google Scholar]
  6. Depuydt S, Hardtke CS (2011) Hormone signalling crosstalk in plant growth regulation. Curr Biol 21: R365–R373 [DOI] [PubMed] [Google Scholar]
  7. Efroni I, Mello A, Nawy T, Ip PL, Rahni R, DelRose N, Powers A, Satija R, Birnbaum KD (2016) Root regeneration triggers an embryo-like sequence guided by hormonal interactions. Cell 165: 1721–1733 [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Fàbregas N, Li N, Boeren S, Nash TE, Goshe MB, Clouse SD, de Vries S, Caño-Delgado AI (2013) The BRASSINOSTEROID INSENSITIVE1-LIKE 3 signalosome complex regulates Arabidopsis root development. Plant Cell 25: 3377–3388 [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Fàbregas N, Lozano-Elena F, Blasco-Escámez D, Tohge T, Martínez-Andújar C, Albacete A, Osorio S, Bustamante M, Riechmann JL, Nomura T, et al. (2018) Overexpression of the vascular brassinosteroid receptor BRL3 confers drought resistance without penalizing plant growth. Nat Commun 9: 4680. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Heyman J, Cools T, Canher B, Shavialenka S, Traas J, Vercauteren I, van den Daele H, Persiau G, De Jaeger G, Sugimoto K, et al. (2016) The heterodimeric transcription factor complex ERF115-PAT1 grants regeneration competence. Nat Plants 2: 16165. [DOI] [PubMed] [Google Scholar]
  11. Iwase A, Mitsuda N, Koyama T, Hiratsu K, Kojima M, Arai T, Inoue Y, Seki M, Sakakibara H, Sugimoto K, et al. (2011) The AP2/ERF transcription factor WIND1 controls cell dedifferentiation in Arabidopsis. Curr Biol 21: 508–514 [DOI] [PubMed] [Google Scholar]
  12. Johnson RA, Conklin PA, Tjahjadi M, Missirian V, Toal T, Brady SM, Britt AB (2018) SUPPRESSOR OF GAMMA RESPONSE1 links DNA damage response to organ regeneration. Plant Physiol 176: 1665–1675 [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Li J, Chory J (1997) A putative leucine-rich repeat receptor kinase involved in brassinosteroid signal transduction. Cell 90: 929–938 [DOI] [PubMed] [Google Scholar]
  14. Li J, Wen J, Lease KA, Doke JT, Tax FE, Walker JC (2002) BAK1, an Arabidopsis LRR receptor-like protein kinase, interacts with BRI1 and modulates brassinosteroid signaling. Cell 110: 213–222 [DOI] [PubMed] [Google Scholar]
  15. Matosevich R, Cohen I, Gil-Yarom N, Modrego A, Friedlander-Shani L, Verna C, Scarpella E, Efroni I (2020) Local auxin biosynthesis is required for root regeneration after wounding. Nat Plants 6: 1020–1030 [DOI] [PubMed] [Google Scholar]
  16. Min YK, Asami T, Fujioka S, Murofushi N, Yamaguchi I, Yoshida S (1999) New lead compounds for brassinosteroid biosynthesis inhibitors. Bioorg Med Chem Lett 9: 425–430 [DOI] [PubMed] [Google Scholar]
  17. Nemhauser JL, Mockler TC, Chory J (2004) Interdependency of brassinosteroid and auxin signaling in Arabidopsis. PLoS Biol 2: E258. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Sabatini S, Beis D, Wolkenfelt H, Murfett J, Guilfoyle T, Malamy J, Benfey P, Leyser O, Bechtold N, Weisbeek P, et al. (1999) An auxin-dependent distal organizer of pattern and polarity in the Arabidopsis root. Cell 99: 463–472 [DOI] [PubMed] [Google Scholar]
  19. Saini S, Sharma I, Pati PK (2015) Versatile roles of brassinosteroid in plants in the context of its homoeostasis, signaling and crosstalks. Front Plant Sci 6: 950. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Sena G, Wang X, Liu HY, Hofhuis H, Birnbaum KD (2009) Organ regeneration does not require a functional stem cell niche in plants. Nature 457: 1150–1153 [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Turk EM, Fujioka S, Seto H, Shimada Y, Takatsuto S, Yoshida S, Wang H, Torres QI, Ward JM, Murthy G, et al. (2005) BAS1 and SOB7 act redundantly to modulate Arabidopsis photomorphogenesis via unique brassinosteroid inactivation mechanisms. Plant J 42: 23–34 [DOI] [PubMed] [Google Scholar]
  22. Waki T, Hiki T, Watanabe R, Hashimoto T, Nakajima K (2011) The Arabidopsis RWP-RK protein RKD4 triggers gene expression and pattern formation in early embryogenesis. Curr Biol 21: 1277–1281 [DOI] [PubMed] [Google Scholar]
  23. Wang ZY, Nakano T, Gendron J, He J, Chen M, Vafeados D, Yang Y, Fujioka S, Yoshida S, Asami T, et al. (2002) Nuclear-localized BZR1 mediates brassinosteroid-induced growth and feedback suppression of brassinosteroid biosynthesis. Dev Cell 2: 505–513 [DOI] [PubMed] [Google Scholar]
  24. Winter D, Vinegar B, Nahal H, Ammar R, Wilson GV, Provart NJ (2007) An “Electronic Fluorescent Pictograph” browser for exploring and analyzing large-scale biological data sets. PLoS One 2: e718. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Yin Y, Vafeados D, Tao Y, Yoshida S, Asami T, Chory J (2005) A new class of transcription factors mediates brassinosteroid-regulated gene expression in Arabidopsis. Cell 120: 249–259 [DOI] [PubMed] [Google Scholar]
  26. Zhou W, Lozano-Torres JL, Blilou I, Zhang X, Zhai Q, Smant G, Li C, Scheres B (2019) A jasmonate signaling network activates root stem cells and promotes regeneration. Cell 177: 942–956.e14 [DOI] [PubMed] [Google Scholar]

Associated Data

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

Supplementary Materials

Supplementary Data
plantbiotechnology-39-1-21.1103a-s001.pdf (11MB, pdf)

Articles from Plant Biotechnology are provided here courtesy of Japanese Society for Plant Biotechnology

RESOURCES