Calcium Requirement for Ethylene-Induced Abscission
Calcium Requirement for Ethylene-Induced Abscission
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DOI：
10.1080/01904160802660693
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发表时间：
2009-02
影响因子：
2.1
通讯作者：
Tao Xu;Tianlai Li;M. Qi
中科院分区：
文献类型：
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作者：
Tao Xu;Tianlai Li;M. Qi
摘要乙烯是一种气体植物激素，在植物器官发育过程中起着重要作用。遗传和生物化学证据表明，植物对乙烯的反应是由一个特定的乙烯受体介导的。据记载，钙作为第二信号参与乙烯介导的反应。然而，钙离子（Ca）如何与乙烯诱导的乙烯裂解有关的乙烯诱导的乙烯裂解的机制仍然是未知的。研究了不同钙处理对番茄花梗外植体乙烯诱导脱落过程中钙浓度、降解酶活性和PG表达的影响。结果表明，在乙烯气氛下，直接施用钙能促进外植体的脱落。此外，钙处理的外植体中纤维素酶活性、endo-PG活性和TAPGs mRNA表达均升高。用螯合剂乙二醇-双-（2-氨乙基）-N，N，N′，N′-四乙酸（EGTA）阻断钙流或用TFP抑制钙调素延迟乙烯诱导的细胞凋亡。在EGTA中培养的外植体表现出8%的减少可提取的游离钙的释放区，并表现出延迟的乙烯释放反应。这种效应与乙烯促进的致病反应和“三重反应”相似，被认为是钙依赖性的。结果表明，钙是乙烯诱导的快速裂解所必需的。
ABSTRACT Ethylene, a gaseous plant hormone, plays an important role in plant organ abscission. Both genetic and biochemical evidence suggest that the response of plants to ethylene is mediated by a specific ethylene receptor. It has been documented that calcium as a second signal is involved in the ethylene-mediated response. However, the mechanism of how calcium (Ca) is associated with ethylene induced abscission on ethylene induced abscission is still unknown. We have investigated calcium concentration, activities of degrading enzymes and PG expressions during ethylene induced abscission of tomato pedicel explants with different calcium treatment. The dates showed that direct application of calcium on explants under ethylene would accelerate abscission. Moreover, cellulase activity, endo-PG activity, and TAPGs mRNA expressions were elevated in explants with calcium treatment. Blocking calcium fluxes with chelators ethylene glycol-bis-(2-aminoethyl)-N,N,N′,N′-tetraacetic acid (EGTA) or inhibited calmodulin by TFP delayed ethylene induced abscission. Explants incubated in EGTA showed 8% reduction in extractable free calcium of their abscission zone and exhibited a delayed abscission reaction to ethylene. This effect, similar to the ethylene-promoted pathogenesis response and “triple response”, were found to be calcium dependent. The results indicated that calcium is necessary for the ethylene induced fast abscission.