Arabidopsis leaf flatness is regulated by PPD2 and NINJA through repression of CYCLIN D3 genes

First author: Alexandra Baekelandt; Affiliations: VIB Center for Plant Systems Biology (比利时弗拉芒生物技术研究所植物系统生物学中心): Ghent, Belgium

Corresponding author: Nathalie Gonzalez

In Arabidopsis, reduced expression of the transcriptional regulator PEAPOD2 (PPD2) results in propeller-like (螺旋桨状的) rosettes with enlarged and dome-shaped (圆顶状) leaves. However, the molecular and cellular processes underlying this peculiar (异常的) phenotype remain elusive. Here, we studied the interaction between PPD2 and NOVEL INTERACTOR OF JAZ (NINJA) and demonstrated that ninja loss-of-function plants produce rosettes with dome-shaped leaves similar to those of ppd mutants, but without the increase in size. We showed that ninja mutants have a convex-shaped (凸形的) primary cell cycle arrest front, putatively leading to excessive cell division in the central leaf blade region. Furthermore, ppd and ninja mutants have a similar increase in expression of CYCLIN D3;2 (CYCD3;2) and ectopic overexpression of CYCD3;2 phenocopies (表型模拟) the ppd and ninja rosette and leaf shape phenotype, without affecting the size. Our results reveal a pivotal (关键的) contribution of NINJA in leaf development, in addition to its well-studied function in jasmonate signalling, and imply a new function for D3-type cyclins (细胞周期蛋白) in, at least partially, uncoupling (解偶联) the size and shape phenotypes of ppd leaves.

拟南芥中，降低转录调控基因PEAPOD2，即PPD2的表达会导致莲座叶变得螺旋桨状，同时叶片增大且呈圆顶状。然而，这种特异的表型潜在的分子和细胞学过程仍然不清楚。本文，作者研究了PPD2与NINJA之间的互作关系，并显示了ninja功能缺失突变体莲座叶的圆顶状表型与ppd突变体类似，但叶片大小不变。进一步的研究表明ninja突变体带有凸形的细胞周期停滞前线，可能导致了叶片中部边缘区域过多的细胞分裂。此外，ppd和ninja突变体有着相似的CYCLIN D3;2 (CYCD3;2)表达量增加，并且CYCD3;2的异位表达表型上重现了ppd和ninja突变体的莲座叶表型，但不影响叶片大小。本文的研究揭示了NINJA蛋白除了在茉莉酸信号通路中发挥作用，在叶片发育中也发挥着关键作用，并且本文表明的D3类细胞周期蛋白的新功能至少部分区分开了ppd突变体叶片大小和形状两个性状之间的关联。

doi: https://doi.org/10.1104/pp.18.00327

Journal: Plant Physiology

First Published: 10 July, 2018

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