杨博等《Journal of Integrative Plant Biology》2022年

论文题目：ANAC087 transcription factor positively regulates age-dependent leaf senescence through modulating the expression of multiple target genes in Arabidopsis

论文作者：Qinqin Chen#,Jingli Yan#, Tiantian Tong#, Peiyu Zhao, Shuangshuang Wang, Na Zhou, Xing Cui, Moyu Dai, Yuan-Qing Jiang*, Bo Yang*

论文摘要：Leaf senescence is the final stage of leaf development and appropriate onset andprogression of leaf senescence are critical for reproductive success and fitness. Although great progress has been made in identifying key genes regulating leaf senescence and elucidating the underlining mechanisms in model plant Arabidopsis, there is still a gap to understand the complex regulatory network. In this study, we discovered that Arabidopsis ANAC087 transcription factor (TF) positively modulated leaf senescence. Expression of ANAC087was induced in senescing leaves and the encoded protein acted as a transcriptional activator. Both constitutive and inducible overexpression lines of ANAC087showed earlier senescence than control plants, whereasT-DNA insertion mutation and dominant repression of ANAC087delayed senescence rate. A qRT-PCR profiling showed that expression of an array of senescence-associated genes were up-regulated in inducible ANAC087overexpression plants including BFN1, NYE1, CEP1, RbohD, SAG13, SAG15and VPEs, which are involved in programmed cell death (PCD), chlorophyll degradation and reactive active oxygen (ROS) accumulation. In addition, EMSA and ChIP-qPCR assays demonstrated that ANAC087 directly bound to the canonical NAC recognition sequence (NACRS) motif in promoters of its target genes. Moreover, mutation of two representative target genes, BFN1or NYE1alleviated the senescence rate of ANAC087-overexpression plants, suggesting their genetic regulatory relationship. Taken together, thisstudy indicates that ANAC087 serves as an important regulator linking PCD, ROS, chlorophyll degradation to leaf senescence.

叶片衰老是叶片生长发育的最后阶段，其发生和发展受到严格控制。叶片衰老与营养物质的转移、再利用以及抗性等的改良密切相关。然而，其中的调控机制仍有未知之处。该研究发现，在叶片衰老过程中ANAC087被高度诱导。ANAC087编码一个具有转录激活的蛋白，且定位在细胞核内。ANAC087的两个T-DNA插入突变体的叶片衰老比野生型（WT）延迟，而组成型以及诱导型过表达ANAC087则明显促进了叶片衰老。进一步筛选与分析发现，ANAC087的过表达上调了多个与叶绿素降解、活性氧（ROS）的生成以及程序性细胞死亡（PCD）相关的基因的转录，包括BFN1, NYE1, CEP1, RbohD, SAG13, SAG15and VPEs等。体外凝胶迁移分析（EMSA）以及体内染色质免疫共沉淀（ChIP）和双荧光素酶分析结果表明，ANAC087可与这些基因的启动子区域的NACRS顺式作用元件直接结合以激活它们表达。遗传分析结果表明，其中的两个靶标基因，BFN1和NYE1的突变减轻了过表达ANAC087引起的早衰表型，暗示ANAC087位于BFN1和NYE1的上游。因此，该研究揭示了ANAC087通过调控PCD、ROS以及叶绿素降解相关的转录以正向调控叶片衰老。

文章链接：https://onlinelibrary.wiley.com/doi/abs/10.1111/jipb.13434