The reduction in maize leaf growth under mild drought affects the transition between cell division and cell expansion and cannot be restored by elevated gibberellic acid levels

Corresponding author: Dirk Inzé

Growth is characterized by the interplay (相互作用) between cell division (细胞分裂) and cell expansion (细胞扩增), two processes that occur separated along the growth zone (生长区) at the maize leaf. To gain further insight into the transition (转变) between cell division and cell expansion, conditions were investigated in which the position of this transition zone (转变区) was positively or negatively affected. High levels of gibberellic acid (GA) in plants overexpressing the GA biosynthesis gene GA20-OXIDASE (GA20OX-1OE) shifted the transition zone more distally (上部), whereas mild drought (轻度干旱), which is associated with lowered GA biosynthesis, resulted in a more basal positioning. However, the increased levels of GA in the GA20OX-1OE line were insufficient (不足的) to convey tolerance to the mild drought treatment, indicating that another mechanism in addition to lowered GA levels is restricting growth during drought. Transcriptome analysis with high spatial resolution indicated that mild drought specifically induces a reprogramming of transcriptional regulation in the division zone. ‘Leaf Growth Viewer’ was developed as an online searchable tool containing the high-resolution data.

生长是细胞分裂与细胞扩增两者间的相互作用，在玉米叶片的生长区中，这两个生物学进程分别起作用。为了进一步了解细胞分裂与细胞扩增之间的转变，作者研究了导致转变区正向或者反向调控的条件。通过过表达赤霉素GA生物合成相关基因GA20-OXIDASE获得的高水平GA株系GA20OX-1OE会将转变区向叶子的上部迁移，而与低水平GA相关的轻微干旱处理则会导致转变区在叶片基部。然而，在GA20OX-1OE株系中GA的增加并不足以克服轻微干旱处理的影响，表明除了低水平的GA之外，存在其它的机制在干旱条件下限制生长。高空间分辨率的转录组分析显示轻微干旱特异地诱导分裂区的转录调控重编程。作者还开发了一款包含高分辨率数据的‘Leaf Growth Viewer’在线搜索工具。

研究方向：调控植物器官生长和作物产量的复杂分子网络破译。

doi: 10.1111/pbi.12801

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