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Brassinazole resistant 1 (BZR1)-dependent brassinosteroid signalling pathway leads to ectopic activation of quiescent cell division and suppresses columella stem cell differentiation.

Lee HS, Kim Y, Pham G, Kim JW, Song JH, Lee Y, Hwang YS, Roux SJ, Kim SH - J. Exp. Bot. (2015)

Bottom Line: BR promotes intense nuclear accumulation of BZR1 in the root tip area, and the binding of BZR1 to the promoters of several root development-regulating genes, modulating their expression in the root stem cell niche area.They could also inhibit auxin-dependent distal stem cell differentiation by antagonizing the auxin/WOX5-dependent pathway.In conclusion, BZR1-/BES1-mediated BR signalling pathways show differential effects on the maintenance of root apical meristem activities: they stimulate ectopic QC division while they show opposite effects on the differentiation of distal columella stem cells in a BR concentration- and BZR1-/BES1-dependent manner.

View Article: PubMed Central - PubMed

Affiliation: Division of Biological Science and Technology, Yonsei University, Wonju, 220-710, Republic of Korea.

No MeSH data available.


Related in: MedlinePlus

BZR1-mediated BR signalling pathway partly acts upstream of auxin in the regulation of CSC differentiation. (A) Effects of auxin-related chemicals on the differentiation of distal CSCs in Col-0 and bzr1-D plants. (B) Pictures of representative seedlings used for the cell layer measurement presented in (A). Seedlings were grown for 8 DAG on 1/2 MS agar media in the absence or presence of NAA (10−6 M) and PEO-IAA (2×10−5 M). The CSC and CC layers were identified as described in Fig. 2. n>50 seedlings for each treatment. (This figure is available in colour at JXB online.)
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Figure 3: BZR1-mediated BR signalling pathway partly acts upstream of auxin in the regulation of CSC differentiation. (A) Effects of auxin-related chemicals on the differentiation of distal CSCs in Col-0 and bzr1-D plants. (B) Pictures of representative seedlings used for the cell layer measurement presented in (A). Seedlings were grown for 8 DAG on 1/2 MS agar media in the absence or presence of NAA (10−6 M) and PEO-IAA (2×10−5 M). The CSC and CC layers were identified as described in Fig. 2. n>50 seedlings for each treatment. (This figure is available in colour at JXB online.)

Mentions: The auxin signalling pathway that stimulates differentiation of CSCs requires activation of auxin responding factors, ARF10 and ARF16 and subsequent restriction of WOX5 transcription in the QC (Wang et al., 2005; Ding and Friml, 2010). Based on these findings, whether the inhibitory effect of the BZR1-mediated BR signalling pathway involves interaction with auxin activities in the distal area was examined. Ninety percent of Col-0 plants grown on MS media without exogenous BL carried a single-layered CSC and the remaining 10% of plants had two layers of CSCs (Fig. 3A, B). In the same population, 23% of the Col-0 plants had five- or six-layered, 64% had four-layered, and 13% had three-layered CCs. As reported previously (Ding and Friml, 2010), Col-0 seedlings grown on medium supplemented with an auxin (1-naphthaleneacetic acid, NAA) led to a decrease in CSC layers and a resulting increase in CC layers. For example, the frequency of plants with single-layered CSCs in NAA-treated Col-0 seedlings was greatly decreased to 52% from 90% in the untreated Col-0 plants. Moreover, 48% of the NAA-treated plants showed no CSC at all. Accordingly, the frequency of NAA-treated plants with more CC layers increased significantly: 30% of the auxin-treated plants carried six-layered CCs, 35% with five-layered, and the remaining 35% had four-layered CCs. Conversely, treatment of plants with an auxin action inhibitor (PEO-IAA, Yoshimoto et al., 2012) increased plants with more CSC layers and with fewer CC layers compared with those of Col-0 plants.


Brassinazole resistant 1 (BZR1)-dependent brassinosteroid signalling pathway leads to ectopic activation of quiescent cell division and suppresses columella stem cell differentiation.

Lee HS, Kim Y, Pham G, Kim JW, Song JH, Lee Y, Hwang YS, Roux SJ, Kim SH - J. Exp. Bot. (2015)

BZR1-mediated BR signalling pathway partly acts upstream of auxin in the regulation of CSC differentiation. (A) Effects of auxin-related chemicals on the differentiation of distal CSCs in Col-0 and bzr1-D plants. (B) Pictures of representative seedlings used for the cell layer measurement presented in (A). Seedlings were grown for 8 DAG on 1/2 MS agar media in the absence or presence of NAA (10−6 M) and PEO-IAA (2×10−5 M). The CSC and CC layers were identified as described in Fig. 2. n>50 seedlings for each treatment. (This figure is available in colour at JXB online.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4507784&req=5

Figure 3: BZR1-mediated BR signalling pathway partly acts upstream of auxin in the regulation of CSC differentiation. (A) Effects of auxin-related chemicals on the differentiation of distal CSCs in Col-0 and bzr1-D plants. (B) Pictures of representative seedlings used for the cell layer measurement presented in (A). Seedlings were grown for 8 DAG on 1/2 MS agar media in the absence or presence of NAA (10−6 M) and PEO-IAA (2×10−5 M). The CSC and CC layers were identified as described in Fig. 2. n>50 seedlings for each treatment. (This figure is available in colour at JXB online.)
Mentions: The auxin signalling pathway that stimulates differentiation of CSCs requires activation of auxin responding factors, ARF10 and ARF16 and subsequent restriction of WOX5 transcription in the QC (Wang et al., 2005; Ding and Friml, 2010). Based on these findings, whether the inhibitory effect of the BZR1-mediated BR signalling pathway involves interaction with auxin activities in the distal area was examined. Ninety percent of Col-0 plants grown on MS media without exogenous BL carried a single-layered CSC and the remaining 10% of plants had two layers of CSCs (Fig. 3A, B). In the same population, 23% of the Col-0 plants had five- or six-layered, 64% had four-layered, and 13% had three-layered CCs. As reported previously (Ding and Friml, 2010), Col-0 seedlings grown on medium supplemented with an auxin (1-naphthaleneacetic acid, NAA) led to a decrease in CSC layers and a resulting increase in CC layers. For example, the frequency of plants with single-layered CSCs in NAA-treated Col-0 seedlings was greatly decreased to 52% from 90% in the untreated Col-0 plants. Moreover, 48% of the NAA-treated plants showed no CSC at all. Accordingly, the frequency of NAA-treated plants with more CC layers increased significantly: 30% of the auxin-treated plants carried six-layered CCs, 35% with five-layered, and the remaining 35% had four-layered CCs. Conversely, treatment of plants with an auxin action inhibitor (PEO-IAA, Yoshimoto et al., 2012) increased plants with more CSC layers and with fewer CC layers compared with those of Col-0 plants.

Bottom Line: BR promotes intense nuclear accumulation of BZR1 in the root tip area, and the binding of BZR1 to the promoters of several root development-regulating genes, modulating their expression in the root stem cell niche area.They could also inhibit auxin-dependent distal stem cell differentiation by antagonizing the auxin/WOX5-dependent pathway.In conclusion, BZR1-/BES1-mediated BR signalling pathways show differential effects on the maintenance of root apical meristem activities: they stimulate ectopic QC division while they show opposite effects on the differentiation of distal columella stem cells in a BR concentration- and BZR1-/BES1-dependent manner.

View Article: PubMed Central - PubMed

Affiliation: Division of Biological Science and Technology, Yonsei University, Wonju, 220-710, Republic of Korea.

No MeSH data available.


Related in: MedlinePlus