State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Peking-Tsinghua Center for Life Sciences, Beijing 100871, China.
J Integr Plant Biol. 2012 Aug;54(8):526-39. doi: 10.1111/j.1744-7909.2012.01136.x.
Plant leaf senescence has been recognized as the last phase of plant development, a highly ordered process regulated by genes known as senescence associated genes (SAGs). However, the function of most of SAGs in regulating leaf senescence as well as regulators of those functionally known SAGs are still unclear. We have previously developed a curated database of genes potentially associated with leaf senescence, the Leaf Senescence Database (LSD). In this study, we built gene networks to identify common regulators of leaf senescence in Arabidopsis thaliana using promoting or delaying senescence genes in LSD. Our results demonstrated that plant hormones cytokinin, auxin, nitric oxide as well as small molecules, such as Ca(2+), delay leaf senescence. By contrast, ethylene, ABA, SA and JA as well as small molecules, such as oxygen, promote leaf senescence, altogether supporting the idea that phytohormones play a critical role in regulating leaf senescence. Functional analysis of candidate SAGs in LSD revealed that a WRKY transcription factor WRKY75 and a Cys2/His2-type transcription factor AZF2 are positive regulators of leaf senescence and loss-of-function of WRKY75 or AZF2 delayed leaf senescence. We also found that silencing of a protein phosphatase, AtMKP2, promoted early senescence. Collectively, LSD can serve as a comprehensive resource for systematic study of the molecular mechanism of leaf senescence as well as offer candidate genes for functional analyses.
植物叶片衰老被认为是植物发育的最后阶段，是一个由称为衰老相关基因（SAGs）的基因调控的高度有序的过程。然而，大多数 SAG 在调节叶片衰老中的功能以及那些功能已知的 SAG 的调节剂仍然不清楚。我们之前开发了一个经过精心整理的与叶片衰老相关的基因数据库，即叶片衰老数据库（LSD）。在这项研究中，我们使用 LSD 中的促进或延迟衰老的基因构建了基因网络，以鉴定拟南芥叶片衰老的共同调节剂。我们的结果表明，植物激素细胞分裂素、生长素、一氧化氮以及小分子如 Ca(2+) 可以延迟叶片衰老。相比之下，乙烯、ABA、SA 和 JA 以及小分子如氧则促进叶片衰老，这共同支持了植物激素在调节叶片衰老中起着关键作用的观点。对 LSD 中候选 SAG 的功能分析表明，WRKY 转录因子 WRKY75 和 Cys2/His2 型转录因子 AZF2 是叶片衰老的正调节剂，WRKY75 或 AZF2 的功能丧失会延迟叶片衰老。我们还发现，一种蛋白磷酸酶 AtMKP2 的沉默会促进早期衰老。总的来说，LSD 可以作为系统研究叶片衰老分子机制的综合资源，并为功能分析提供候选基因。
