SHOEBOX Modulates Root Meristem Size in Rice through Dose-Dependent Effects of Gibberellins on Cell Elongation and Proliferation.
SHOEBOX Modulates Root Meristem Size in Rice through Dose-Dependent Effects of Gibberellins on Cell Elongation and Proliferation.
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SHOEBOX 通过赤霉素对细胞伸长和增殖的剂量依赖性效应来调节水稻根分生组织的大小。
DOI：
10.1371/journal.pgen.1005464
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发表时间：
2015-08
期刊：
影响因子：
4.5
通讯作者：
Xu J
中科院分区：
文献类型：
--
作者：
Li J;Zhao Y;Chu H;Wang L;Fu Y;Liu P;Upadhyaya N;Chen C;Mou T;Feng Y;Kumar P;Xu J
在植物中，分生组织细胞的大小是如何调控的，以及它是否参与分生组织大小的调控，目前所知甚少。在这里，我们报告了我们对shoebox （shb）的发现，这是一种轻度赤霉素（GA）缺乏的水稻突变体，具有短的根分生组织大小。对皮质细胞长度和数量的定量分析表明，播后第5天左右，shb根分生组织中细胞的长度较短，而不是较少，从第5天开始，皮质细胞的数量也减少了。这些缺陷既可以通过外源施用具有生物活性的GA来纠正，也可以通过多效丁唑对GA生物合成的剂量依赖性抑制作用在野生型根中诱导，这表明GA缺乏是shb突变表型的主要原因。SHB编码AP2/ERF转录因子，直接激活GA生物合成基因KS1的转录。因此，水稻根分生组织的大小受到shb介导的GA生物合成的调节，该生物合成以特定发育阶段的方式调节分生组织细胞的伸长和增殖。关于控制植物分生组织细胞生长的调控成分和信号通路的身份知之甚少。在此，我们报道了AP2/ERF家族SHOEBOX （SHB）基因缺失的水稻植株根系分生组织大小严重减少。这些植株在萌发后的根分生组织中细胞较短，在播种后约5天细胞较少，表明SHB以特定发育阶段的方式调节根分生组织细胞的大小和数量，细胞大小参与水稻根分生组织大小的控制。SHB受GA信号的正调控，并编码GA生物合成基因KS1的直接转录激活因子，表明GA通过对SHB和KS1转录的正反馈调控来调节自身的生物合成，从而调控水稻根分生组织细胞的伸长。在shb和多效唑处理的野生型植物中，外源GA的应用同样使根分生组织细胞的大小恢复正常。
Little is known about how the size of meristem cells is regulated and whether it participates in the control of meristem size in plants. Here, we report our findings on shoebox (shb), a mild gibberellin (GA) deficient rice mutant that has a short root meristem size. Quantitative analysis of cortical cell length and number indicates that shb has shorter, rather than fewer, cells in the root meristem until around the fifth day after sowing, from which the number of cortical cells is also reduced. These defects can be either corrected by exogenous application of bioactive GA or induced in wild-type roots by a dose-dependent inhibitory effect of paclobutrazol on GA biosynthesis, suggesting that GA deficiency is the primary cause of shb mutant phenotypes. SHB encodes an AP2/ERF transcription factor that directly activates transcription of the GA biosynthesis gene KS1. Thus, root meristem size in rice is modulated by SHB-mediated GA biosynthesis that regulates the elongation and proliferation of meristem cells in a developmental stage-specific manner. Little is known concerning the identity of regulatory components and signaling pathways that control the growth of meristem cells in plants. Here, we report that rice plants deficient in the AP2/ERF family gene SHOEBOX (SHB) exhibited a severe reduction in the root meristem size. These plants had shorter cells in the root meristems following germination and fewer cells from approximately 5 days after sowing, suggesting that SHB regulates root meristem cell size and number in a developmental stage-specific manner and that cell size participates in the control of root meristem size in rice. SHB is positively regulated by GA signaling and encodes a direct transcriptional activator of the GA biosynthesis gene KS1, indicating that GA modulates its own biosynthesis and consequently the elongation of meristem cells in rice roots via positive feedback regulation on the transcription of SHB and KS1. Consistently, application of exogenous GA restored the size of root meristem cells to normal in shb and paclobutrazol-treated wild-type plants.