Positive Autoregulation of a KNOX Gene Is Essential for Shoot Apical Meristem Maintenance in Rice
Positive Autoregulation of a KNOX Gene Is Essential for Shoot Apical Meristem Maintenance in Rice
复制标题
DOI：
10.1105/tpc.111.090050
复制
发表时间：
2011-12-01
期刊：
影响因子：
11.6
通讯作者：
Kurata, Nori
中科院分区：
文献类型：
--
作者：
Tsuda, Katsutoshi;Ito, Yukihiro;Kurata, Nori
茎顶端分生组织（SAM）是植物生长发育过程中的重要组成部分。I类结1样同源异型盒（KNOX）基因限制细胞分化，并在维持SAM中发挥不可或缺的作用。然而，积极调节其表达的机制尚不清楚。在这里，我们表明，表达的水稻（水稻）KNOX基因，水稻同源框1（OSH1），是正调控的直接自动调节。有趣的是，OSH 1的功能丧失突变体在萌发后就失去了SAM，但当它们从愈伤组织再生时，可以被拯救生长直到生殖发育。双突变体osh1和d6，一个OSH15的功能丧失突变体，未能建立SAM在胚胎发生和再生。在这些突变体中的表达分析表明，KNOX基因的表达正调控的植物激素细胞分裂素和KNOX基因本身。我们证明，OSH1直接结合到5个KNOX位点，包括OSH1和OSH15，通过进化保守的顺式元件和OSH1的积极的自动调节是必不可少的，其自身的表达和SAM的维护。因此，由KNOX基因的正性自身调节介导的不确定状态的维持是SAM自我维持的不可或缺的机制。
Self-maintenance of the shoot apical meristem (SAM), from which aerial organs are formed throughout the life cycle, is crucial in plant development. Class I Knotted1-like homeobox (KNOX) genes restrict cell differentiation and play an indispensable role in maintaining the SAM. However, the mechanism that positively regulates their expression is unknown. Here, we show that expression of a rice (Oryza sativa) KNOX gene, Oryza sativa homeobox1 (OSH1), is positively regulated by direct autoregulation. Interestingly, loss-of-function mutants of OSH1 lose the SAM just after germination but can be rescued to grow until reproductive development when they are regenerated from callus. Double mutants of osh1 and d6, a loss-of-function mutant of OSH15, fail to establish the SAM both in embryogenesis and regeneration. Expression analyses in these mutants reveal that KNOX gene expression is positively regulated by the phytohormone cytokinin and by KNOX genes themselves. We demonstrate that OSH1 directly binds to five KNOX loci, including OSH1 and OSH15, through evolutionarily conserved cis-elements and that the positive autoregulation of OSH1 is indispensable for its own expression and SAM maintenance. Thus, the maintenance of the indeterminate state mediated by positive autoregulation of a KNOX gene is an indispensable mechanism of self-maintenance of the SAM.