Increase in reactive oxygen species (ROS) and in senescence-associated gene transcript (SAG) levels during dark-induced senescence of Pelargonium cuttings, and the effect of gibberellic acid
Increase in reactive oxygen species (ROS) and in senescence-associated gene transcript (SAG) levels during dark-induced senescence of Pelargonium cuttings, and the effect of gibberellic acid
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DOI：
10.1016/j.plantsci.2005.12.010
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发表时间：
2006-04-01
期刊：
影响因子：
5.2
通讯作者：
Friedman, H
中科院分区：
文献类型：
--
作者：
Rosenwasser, S;Mayak, S;Friedman, H
黑暗诱导的天竺葵叶片衰老表现在叶绿素分解，活性氧（ROS）水平的增加，随后诱导两个衰老相关基因（SAG）转录本：衰老相关转录因子PeWRKY6 - 1和半胱氨酸蛋白酶同源物PeSAG12 - 1。在ROS增加开始时施用谷氨酰胺，减少ROS积累并阻止PeSAG12 - 1表达的增加。这些结果表明，在黑暗中，PeSAG12 - 1和可能的PeWRKY6 - 1是由ROS水平的增加诱导的。由于PeWRKY6 - 1的表达与PeSAG12 - 1的表达同时增加，因此它很可能不起衰老诱导剂的作用。在黑暗处理之前向天竺葵插条施用赤霉素（GA（3））防止了叶绿素分解、ROS增加以及PeWRKY6 - 1和PeSAG12 - 1的积累。GA（3）在ROS积累开始的黑暗时期施用也降低ROS水平，但在高ROS水平明显之后施用时不降低。GA（3）抑制活性氧水平的模式与其抑制叶绿素分解的效果呈正相关。然而，在ROS积累后应用GA（3）抑制PeWRKY6 - 1和PeSAG12 - 1基因表达，尽管组织中的ROS水平较高。综上所述，我们的研究结果表明，GA（3）的作用，以抑制天竺葵叶片衰老，可能不仅通过降低ROS水平，但也通过干扰衰老调节，通过一个未知的机制。(c)2006年由Elsevier爱尔兰有限公司出版。
Dark-induced senescence in the leaves of Pelargonium cuttings was manifested in chlorophyll breakdown, and an increase in reactive oxygen species (ROS) levels followed by a subsequent induction of two senescence-associated gene (SAG) transcripts: senescence-related transcription factor PeWRKY6-1 and cystein protease homolog PeSAG12-1. Glutathione applied at the onset of ROS increase, reduced ROS accumulation and prevented the increase in PeSAG12-1 expression. These results suggest that in darkness PeSAG12-1 and maybe PeWRKY6-1 are induced by increases in ROS levels. Since PeWRKY6-1 expression increased concomitantly with that of PeSAG12-1, it most likely does not function as a senescence inducer.Application of gibberellic acid (GA(3)) to Pelargonium cuttings before the dark treatment prevented chlorophyll breakdown, ROS increase and PeWRKY6-1 and PeSAG12-1 accumulation. GA(3) also decreased ROS levels when it was applied during the dark period at the onset of ROS accumulation, but not when applied after high ROS levels were evident. The pattern of GA(3) suppression of ROS levels positively correlated with its inhibitory effect on chlorophyll breakdown. However, GA(3) application after ROS accumulation inhibited PeWRKY6-1 and PeSAG12-1 gene expressions, despite high ROS levels in the tissue. Taken together, our results suggest that GA(3) acts to inhibit leaf senescence of Pelargonium, probably not only by reducing ROS levels, but also by interfering with senescence regulation, through an as yet unknown mechanism. (c) 2006 Published by Elsevier Ireland Ltd.