RhHB1 mediates the antagonism of gibberellins to ABA and ethylene during rose ( Rosa hybrida) petal senescence
RhHB1 mediates the antagonism of gibberellins to ABA and ethylene during rose ( Rosa hybrida) petal senescence
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RhHB1在玫瑰花瓣衰老过程中介导赤霉素对ABA和乙烯的拮抗作用
DOI：
10.1111/tpj.12494
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发表时间：
2014-05-01
期刊：
影响因子：
7.2
通讯作者：
Gao, Junping
中科院分区：
文献类型：
--
作者：
Lu, Peitao;Zhang, Changqing;Gao, Junping
玫瑰（Rosa hybrida）是全球最重要的观赏植物之一；然而，其花瓣的衰老终止了花的观赏价值，造成重大的经济损失。众所周知，脱落酸（ABA）和乙烯激素促进花瓣衰老，而赤霉素（GAs）延缓这一过程。然而，植物激素在花瓣衰老过程中拮抗作用的分子机制尚不清楚。本研究从玫瑰花中分离出同源结构域亮氨酸拉链I转录因子基因RhHB1。定量RT-PCR和GUS报告基因分析表明，RhHB1在衰老花瓣中表达强烈，其表达受ABA或乙烯诱导。ABA或乙烯处理明显加速了玫瑰花瓣的衰老，而赤霉素GA(3)延缓了这一进程。然而，RhHB1的沉默延缓了ABA或乙烯介导的衰老，并导致花瓣花青素水平升高和RhSAG12的表达降低。此外，用多效唑（一种GA生物合成抑制剂）治疗可以抑制这些延迟。此外，RhHB1的沉默阻断了ABA或乙烯诱导的GA20氧化酶表达的减少，该氧化酶由RhGA20ox1编码，是GA生物合成途径中的一个基因。此外，RhHB1直接与RhGA20ox1启动子结合，RhGA20ox1的沉默促进了花瓣衰老。GA(3)和多效唑处理后，8个衰老相关基因在花瓣中的表达存在显著差异。这些结果表明，RhHB1介导了GAs在玫瑰花瓣衰老过程中对ABA和乙烯的拮抗作用，ABA或乙烯对花瓣衰老的促进作用是通过RhHB1- rhga20ox1调控点实现的。
Rose (Rosa hybrida) is one of the most important ornamental plants worldwide; however, senescence of its petals terminates the ornamental value of the flower, resulting in major economic loss. It is known that the hormones abscisic acid (ABA) and ethylene promote petal senescence, while gibberellins (GAs) delay the process. However, the molecular mechanisms underlying the antagonistic effects amongst plant hormones during petal senescence are still unclear. Here we isolated RhHB1, a homeodomain-leucine zipper I transcription factor gene, from rose flowers. Quantitative RT-PCR and GUS reporter analyses showed that RhHB1 was strongly expressed in senescing petals, and its expression was induced by ABA or ethylene in petals. ABA or ethylene treatment clearly accelerated rose petal senescence, while application of the gibberellin GA(3) delayed the process. However, silencing of RhHB1 delayed the ABA- or ethylene-mediated senescence, and resulted in higher petal anthocyanin levels and lower expression of RhSAG12. Moreover, treatment with paclobutrazol, an inhibitor of GA biosynthesis, repressed these delays. In addition, silencing of RhHB1 blocked the ABA- or ethylene-induced reduction in expression of the GA20 oxidase encoded by RhGA20ox1, a gene in the GA biosynthetic pathway. Furthermore, RhHB1 directly binds to the RhGA20ox1 promoter, and silencing of RhGA20ox1 promoted petal senescence. Eight senescence-related genes showed substantial differences in expression in petals after treatment with GA(3) or paclobutrazol. These results suggest that RhHB1 mediates the antagonistic effect of GAs on ABA and ethylene during rose petal senescence, and that the promotion of petal senescence by ABA or ethylene operates through an RhHB1-RhGA20ox1 regulatory checkpoint.