【摘要】 WUS(WUSCHEL)基因编码一转录因子,它的存在使周围细胞具有干细胞的特征,与之相关的信号系统近年逐步被阐明。在茎尖分生组织内WUS和CLV(CLAVATA)之间形成一个反馈调节环,使得干细胞保持自我更新,维持茎尖的顶端优势。在胚胎分生组织内,CLV3的表达只依赖于WUS的存在,然而在胚以后的发育中,CLV3的表达受到WUS和STM(SHOOTMERISTEMLESS)的双重调节,启动器官发生。在花分生组织中,WUS和LFY(LEAFY)共同激活AG(AGAMOUS)基因的表达,WUS受AG的反馈抑制。由WUS建立的信号体系还参与胚珠的发育。当WUS蛋白和生长素共存时,可以高效启动体细胞胚的发生。细胞对WUS信号的感应性与细胞所处的微环境有关,WUS在不同环境条件下可以启动不同的下游基因表达。更多还原

【Abstract】 The WUS (WUSCHEL) gene encodes a transcription factor that specifies the adjacent cells to be stem cell. The WUS dependent signal systems have been found in different tissues re- cent years. The feedback loop between the CLV and WUS genes maintains the stem cell self-re- newal and apical dominance in shoot apical meristem. In the embryonic meristem, the ex- pression of CLV3 depends on WUS only. Dur- ing post-embryo development, both WUS and STM are needed for CLV3 expression and the triggering of organogenesis. The expression of AG in floral meristem is activated by co-exist- ence of WUS and LFY, AG acts as a negative regulator of WUS expression to downregulate theWUS level. The signal system established by WUS is also involved in ovule development. The somatic embryogenesis can be promoted effi- ciently by WUS, especially in the presence of auxin. The results of prevoius works indicated that cell competence to WUS activity is related to microenvironment and the combination of WUS signal with different environmental fac- tors could activate different downstream genes.更多还原