Overproduction of cytokinins in petunia flowers transformed with PSAG12-IPT delays corolla senescence and decreases sensitivity to ethylene
Overproduction of cytokinins in petunia flowers transformed with PSAG12-IPT delays corolla senescence and decreases sensitivity to ethylene
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DOI：
10.1104/pp.103.023945
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发表时间：
2003-08-01
期刊：
影响因子：
7.4
通讯作者：
Clark, DG
中科院分区：
文献类型：
--
作者：
Chang, HS;Jones, ML;Clark, DG
植物衰老是由一个协调的遗传程序介导的，部分是通过乙烯，脱落酸（阿坝）和细胞分裂素含量的变化。具有延迟衰老的转基因植物对于研究这些信号传导机制之间的相互作用是有用的。ipt是根癌农杆菌的细胞分裂素生物合成基因，在衰老相关基因（SAG 12）的启动子的控制下表达ipt是用于延缓衰老的一种方法。我们用P（SAG 12）-IPT转化矮牵牛（Petuniaxhybridacv V26）。以两个独立的花寿命延长的转化系（I-1-7-22和I-3-18-34）为材料，研究了细胞分裂素含量升高对矮牵牛花冠乙烯合成、乙烯敏感性和阿坝积累的影响。在这些罚款花衰老延迟6至10天相对于野生型（WT）花。授粉后Ipt转录本大量增加，并伴随着细胞分裂素积累增加。授粉诱导WT和IPT花冠内源乙烯产生，但这种增加被推迟在IPT花。IPT植物的花对外源乙烯不太敏感，需要更长的处理时间来诱导内源乙烯产生，花冠衰老，和衰老相关的半胱氨酸蛋白酶phcp 1的上调。阿坝的积累，另一种激素调节花衰老，是显着更大的野生型花冠，证实花衰老被推迟在IPT植物。这些结果扩展了我们对调节花衰老的激素相互作用的理解，并提供了一种增加花寿命的方法。
Plant senescence is regulated by a coordinated genetic program mediated in, part by changes in ethylene, abscisic acid (ABA), and cytokinin content. Transgenic plants with delayed senescence are useful for studying interactions between these signaling mechanisms. Expression of ipt, a cytokinin biosynthetic gene from Agrobacterium tumefaciens, under the control of the promoter from a senescence-associated gene (SAG12) has been one approach used to delay senescence. We transformed petunia (Petunia x hybrida cv V26) with P(SAG12)-IPT. Two independently transformed lines with extended flower longevity (I-1-7-22 and I-3-18-34) were used to study the effects of elevated cytokinin content on ethylene synthesis and sensitivity and ABA accumulation in petunia corollas. Floral senescence in these fines was delayed 6 to 10 d relative to wild-type (WT) flowers. Ipt transcripts increased in abundance after pollination and were accompanied by increased cytokinin accumulation. Endogenous ethylene production was induced by pollination in both WT and IPT corollas, but this increase was delayed in IPT flowers. Flowers from IPT plants were less sensitive to exogenous ethylene and required longer treatment times to induce endogenous ethylene production, corolla senescence, and up-regulation of the senescence-related Cys protease phcp1. Accumulation of ABA, another hormone regulating flower senescence, was significantly greater in WT corollas, confirming that floral senescence was delayed in IPT plants. These results extend our understanding of the hormone interactions that regulate flower senescence and provide a means of increasing flower longevity.