Increases in DNA fragmentation and induction of a senescence-specific nuclease are delayed during corolla senescence in ethylene-insensitive (etr1-1) transgenic petunias
Increases in DNA fragmentation and induction of a senescence-specific nuclease are delayed during corolla senescence in ethylene-insensitive (etr1-1) transgenic petunias
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DOI：
10.1093/jxb/eri002
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发表时间：
2005-01-01
影响因子：
6.9
通讯作者：
Jones, ML
中科院分区：
文献类型：
--
作者：
Langston, BJ;Bai, S;Jones, ML
花瓣的程序性衰老已被证明与核 DNA 的断裂有关。通过 TUNEL 测定，在授粉诱导和年龄相关的衰老过程中，在矮牵牛花冠中检测到了核 DNA 片段化。 DNA 片段在花朵生命后期检测到，当时花冠枯萎并产生乙烯。 43 kDa 核酸酶 (PhNUC1) 的诱导与 DNA 片段化增加相关。 PhNUC1 是一种糖蛋白，具有抗 DNA 和 RNA 的活性，最适 pH 值为 7.5。研究发现 EDTA 会抑制 PhNUC1 活性，但添加 Co2+ 可在螯合剂存在的情况下恢复活性。当通过差速离心分离衰老花瓣的总蛋白提取物时，在细胞核中检测到 PhNUC1 活性，但在细胞质部分中未检测到。通过乙烯处理，在未衰老的花冠中诱导 PhNUC1 的活性。在对乙烯不敏感的花 (35S:etr1-1) 中观察到 PhNUC1 活性的延迟增加表明乙烯调节 PhNUC1 诱导的时间，但这并不是其激活的绝对要求。
The programmed senescence of flower petals has been shown to involve the fragmentation of nuclear DNA. Nuclear DNA fragmentation, as determined by the TUNEL assay, was detected in Petunia x hybrida corollas during both pollination-induced and age-related senescence. DNA fragmentation was detected late in the lifespan of the flower when corollas were wilting and producing ethylene. The induction of a 43 kDa nuclease (PhNUC1) correlated with increased DNA fragmentation. PhNUC1 is a glycoprotein with activity against DNA and RNA and a pH optimum of 7.5. EDTA was found to inhibit PhNUC1 activity, but the addition of Co2+ restored activity in the presence of the chelating agent. When total protein extracts from senescing petals were fractionated by differential centrifugation, PhNUC1 activity was detected in the nuclear but not the cytoplasmic fraction. Activity of PhNUC1 was induced in non-senescing corollas by treatment with ethylene. Delayed increases in PhNUC1 activity observed in ethylene-insensitive flowers (35S:etr1-1) suggest that ethylene modulates the timing of PhNUC1 induction, but that it is not an absolute requirement for its activation.