A single-repeat MYB transcription repressor, MYBH, participates in regulation of leaf senescence in Arabidopsis
A single-repeat MYB transcription repressor, MYBH, participates in regulation of leaf senescence in Arabidopsis
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DOI：
10.1007/s11103-015-0321-2
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发表时间：
2015-06-01
影响因子：
5.1
通讯作者：
Lu, Chung-An
中科院分区：
文献类型：
--
作者：
Huang, Chun-Kai;Lo, Pei-Ching;Lu, Chung-An
叶子衰老是叶子发育的最后阶段，受到内源和环境信号的严格调控。 MYBS3 是一种具有单个 DNA 结合域的 MYB 转录因子，介导水稻中的糖信号传导。在此，我们报道拟南芥 MYBS3 同源物 MYBH 通过抑制转录在发育调节和黑暗诱导的叶片衰老中发挥关键作用。 MYBH 的表达在较老和黑暗处理的叶子中增强。功能获得和丧失分析表明 MYBH 参与了叶片衰老的发生。组成型过表达 MYBH 的植物经历了叶片过早衰老，并且叶片衰老标记基因的表达增强。相比之下，MYBH 突变系 mybh-1 表现出延迟衰老表型。 EAR 抑制结构域是 MYBH 调节的叶片衰老所必需的。 MYBH 的过表达和敲除分别抑制和增强了生长素响应基因的表达。 MYBH 通过直接结合每个调节区域的 TA 盒来抑制生长素酰胺合酶基因 DFL1/GH3.6 和 DFL2/GH3.10，从而调节生长素稳态。生长素反应表型在 MYBH 过表达品系中增强，而在 mybh 敲除品系中减少。 MYBH 的过度表达增强了 SAUR36（一种生长素促进的叶片衰老关键调节因子）的基因表达，并加速了转基因拟南芥植物中 ABA 和乙烯诱导的叶片衰老。我们的结果表明，MYBH 在控制生长素稳态中的作用解释了它参与调节拟南芥中年龄和黑暗诱导的叶片衰老的能力。
Leaf senescence, the final stage of leaf development, is regulated tightly by endogenous and environmental signals. MYBS3, a MYB transcription factor with a single DNA-binding domain, mediates sugar signaling in rice. Here we report that an Arabidopsis MYBS3 homolog, MYBH, plays a critical role in developmentally regulated and dark-induced leaf senescence by repressing transcription. Expression of MYBH was enhanced in older and dark-treated leaves. Gain- and loss-of-function analysis indicated that MYBH was involved in the onset of leaf senescence. Plants constitutively overexpressing MYBH underwent premature leaf senescence and showed enhanced expression of leaf senescence marker genes. In contrast, the MYBH mutant line, mybh-1, exhibited a delayed-senescence phenotype. The EAR repression domain was required for MYBH-regulated leaf senescence. Overexpression and knockout of MYBH repressed and enhanced auxin-responsive gene expression, respectively. MYBH repressed the auxin-amido synthase genes DFL1/GH3.6 and DFL2/GH3.10, which regulate auxin homoeostasis, by binding directly to the TA box in each of their regulatory regions. An auxin-responsive phenotype was enhanced in MYBH overexpression lines and reduced in mybh knockout lines. Overexpression of MYBH enhanced gene expression of SAUR36, an auxin-promoted leaf senescence key regulator, and accelerated ABA- and ethylene-induced leaf senescence in transgenic Arabidopsis plants. Our results suggest that the role of MYBH in controlling auxin homeostasis accounts for its capacity to participate in regulation of age- and darkness-induced leaf senescence in Arabidopsis.