State Key Laboratory of Plant Genomics, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Plant Cell. 2011 Sep;23(9):3335-52. doi: 10.1105/tpc.111.089870. Epub 2011 Sep 27.
The root stem cell niche, which in the Arabidopsis thaliana root meristem is an area of four mitotically inactive quiescent cells (QCs) and the surrounding mitotically active stem cells, is critical for root development and growth. We report here that during jasmonate-induced inhibition of primary root growth, jasmonate reduces root meristem activity and leads to irregular QC division and columella stem cell differentiation. Consistently, jasmonate reduces the expression levels of the AP2-domain transcription factors PLETHORA1 (PLT1) and PLT2, which form a developmentally instructive protein gradient and mediate auxin-induced regulation of stem cell niche maintenance. Not surprisingly, the effects of jasmonate on root stem cell niche maintenance and PLT expression require the functioning of MYC2/JASMONATE INSENSITIVE1, a basic helix-loop-helix transcription factor that involves versatile aspects of jasmonate-regulated gene expression. Gel shift and chromatin immunoprecipitation experiments reveal that MYC2 directly binds the promoters of PLT1 and PLT2 and represses their expression. We propose that MYC2-mediated repression of PLT expression integrates jasmonate action into the auxin pathway in regulating root meristem activity and stem cell niche maintenance. This study illustrates a molecular framework for jasmonate-induced inhibition of root growth through interaction with the growth regulator auxin.
根干细胞壁龛在拟南芥根分生组织中是一个包含四个有丝分裂不活跃的静止细胞(QC)和周围有丝分裂活跃的干细胞的区域，对根的发育和生长至关重要。我们在这里报告，在茉莉酸诱导的主根生长抑制过程中，茉莉酸降低了根分生组织的活性，导致 QC 分裂不规则和中柱干细胞分化。一致地，茉莉酸降低了 AP2 结构域转录因子 PLETHORA1 (PLT1) 和 PLT2 的表达水平，PLT1 和 PLT2 形成了一个发育上有指导意义的蛋白质梯度，并介导了生长素诱导的干细胞壁龛维持的调节。毫不奇怪，茉莉酸对根干细胞壁龛维持和 PLT 表达的影响需要 MYC2/JASMONATE INSENSITIVE1 的功能，MYC2 是一种基本螺旋-环-螺旋转录因子，涉及茉莉酸调节基因表达的多个方面。凝胶迁移和染色质免疫沉淀实验表明，MYC2 直接结合 PLT1 和 PLT2 的启动子并抑制它们的表达。我们提出，MYC2 介导的 PLT 表达抑制将茉莉酸作用整合到生长素途径中，以调节根分生组织的活性和干细胞壁龛维持。这项研究说明了茉莉酸通过与生长调节剂生长素相互作用抑制根生长的分子框架。
