J Exp Bo:中科院植生所徐麟研究组揭示生长素控制植物根从头发生
近日，《Journal of Experimental Botany》杂志发表了中国科学院上海生命科学研究院植物生理生态研究所徐麟研究组、湖南农业大学和上海师范大学合作完成题为“YUCCA-mediated auxin biogenesis is required for cell fate transition occurring during de novo root organogenesis in Arabidopsis”的研究论文，揭示了YUC介导的生长素合成途径通过响应伤口以及黑暗环境，参与拟南芥根从头发生过程中细胞命运转变的分子机制。研究论文被当期Insights推荐阅读(J. Exp. Bot. 2016, 67: 4011-4013)。
器官从头发生是植物再生的一种方式，也是植物实现营养繁殖的重要手段。拟南芥离体的叶片外植体可以自发再生不定根，这是研究根从头发生的简单实用体系。前期研究发现，生长素是控制根从头发生过程的核心激素，它能通过直接激活转录因子基因 WOX11的表达,将叶片外植体中靠近伤口处的再生潜能细胞命运转变为根创始细胞，开启根从头发生。但是植物外植体响应外界环境控制内源生长素行为的分子机制并不清楚。
这项研究发现，叶片离体后自由态生长素含量快速上升，这一现象依赖于YUC基因介导的的生长素合成途径。当YUC基因家族成员的功能受到抑制时,叶片外植体中WOX11的表达和细胞命运的转变也受到抑制,无法再生不定根。进一步对YUC基因家族各成员的功能研究发现，叶片离体产生的伤口能快速诱导YUC1和YUC4在叶肉细胞中表达，贡献再生中生长素的需求;黑暗环境能特异诱导YUC5,YUC8和YUC9在叶肉细胞中的表达，增强叶片外植体在黑暗环境下的再生能力;YUC2和YUC6在叶片再生过程中一直维持高水平的表达,暗示这两个基因贡献于叶片本底生长素的合成。以上的结果说明,不同的YUC基因通过分工响应各种环境因素参与到拟南芥根从头发生过程中。
生长素控制植物根从头发生过程
原文链接：
YUCCA-mediated auxin bioGENEsis is required for cell fate transition occurring during de novoroot organogenesis in Arabidopsis
原文摘要：
Many plant organs have the ability to regenerate a new plant after detachment or wounding via de novo organogenesis. During de novo root organogenesis from Arabidopsis thaliana leaf explants, endogenic auxin is essential for the fate transition of regeneration-competent cells to become root founder cells via activation of WUSCHEL-RELATED HOMEOBOX 11 (WOX11). However, the molecular events from leaf explant detachment to auxin-mediated cell fate transition are poorly understood. In this study, we used an assay to determine the concentration of indole-3-acetic acid (IAA) to provide direct evidence that auxin is produced after leaf explant detachment, a process that involves YUCCA (YUC)-mediated auxin biogenesis. Inhibition of YUC prevents expression of WOX11 and fate transition of competent cells, resulting in the blocking of rooting. Further analysis showed that YUC1 and YUC4 act quickly (within 4 hours) in response to wounding after detachment in both light and dark conditions and promote auxin biogenesis in both mesophyll and competent cells, whereas YUC5, YUC8, and YUC9 primarily respond in dark conditions. In addition, YUC2 and YUC6 contribute to rooting by providing a basal auxin level in the leaf. Overall, our study indicates thatYUC genes exhibit a division of labour during de novo root organogenesis from leaf explants in response to multiple signals.
作者：徐麟
