Jasmonate production through chlorophyll a degradation by Stay-Green in Arabidopsis thaliana
Jasmonate production through chlorophyll a degradation by Stay-Green in Arabidopsis thaliana
复制标题
DOI：
10.1016/j.jplph.2019.05.004
复制
发表时间：
2019-07-01
影响因子：
4.3
通讯作者：
Ito, Hisashi
中科院分区：
文献类型：
--
作者：
Ono, Kouhei;Kimura, Madoka;Ito, Hisashi
叶绿素降解引起的叶片颜色变化是衰老的特征症状。从叶绿素a中去除镁是叶绿素a降解的第一步，是由Stay-Green （SGR）催化的反应。拟南芥有三个SGR同源物，SGR1、SGR2和SGR样。当SGR1过表达时，叶绿素a和b都被降解，叶片变黄。这一过程在视觉上与衰老过程相同，表明SGR1过表达影响植物的多种生理过程。为了验证这种可能性，我们分析了地塞米松诱导的SGR1导入拟南芥后与叶绿素代谢和衰老相关的基因表达。当SGR1在地塞米松处理18小时后过表达时，参与叶绿素降解的基因和衰老相关基因被上调。这些观察结果表明，叶绿素a的降解促进衰老。由于茉莉酸盐是植物中负责衰老的激素，预计会参与地塞米松处理后基因表达的调控，因此我们测量了茉莉酸盐的活性形式茉莉醇异亮氨酸的水平。SGR1过表达10h后，茉莉酰异亮氨酸水平略有上升，18h后，茉莉酰异亮氨酸水平上升明显。这说明茉莉酸盐是通过降解叶绿素a产生的，对促进衰老有一定作用。
Leaf color change through chlorophyll degradation is a characteristic symptom of senescence. Magnesium removal from chlorophyll a is the initial step in chlorophyll a degradation, in a reaction catalyzed by Stay-Green (SGR). Arabidopsis thaliana has three SGR homologs, SGR1, SGR2, and SGR-like. When SGR1 is overexpressed, both chlorophyll a and b are degraded and leaves turn yellow. This process is visually identical to senescence, suggesting that SGR1 overexpression affects various physiological processes in plants. To examine this possibility, gene expression associated with chlorophyll metabolism and senescence was analyzed following dexamethasone-inducible SGR1 introduction into Arabidopsis. When SGR1 was overexpressed following 18 h of dexamethasone treatment, genes involved in chlorophyll degradation were upregulated, as were senescence-associated genes. These observations suggested that chlorophyll a degradation promotes senescence. As jasmonate is the plant hormone responsible for senescence and was expected to be involved in the regulation of gene expression after dexamethasone treatment, the level of jasmonoyl-isoleucine, the active form of jasmonate, was measured. The jasmonoyl-isoleucine level increased slightly after 10h of SGR1 overexpression, and this increase became significant after 18 h. These observations suggest that jasmonate is produced through chlorophyll a degradation and affects the promotion of senescence.