RhHB1 mediates the antagonism of gibberellins to ABA and ethylene during rose (Rosa hybrida) petal senescence. (7th April 2014)

• Record Type: Journal Article
• Authors: Lü, Peitao; Zhang, Changqing; Liu, Jitao; Liu, Xiaowei; Jiang, Guimei; Jiang, Xinqiang; Khan, Muhammad Ali; Wang, Liangsheng; Hong, Bo; Gao, Junping
• Is Part Of: Plant journal. Volume 78:Number 4(2014:May)
• Page Start: 578
• Page End: 590
• Publication Date: 2014-04-07
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12494
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12494-abs-0001"> <title>Summary</title> <p>Rose (<italic>Rosa hybrida</italic>) 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 <italic>RhHB1</italic>, a homeodomain‐leucine zipper I transcription factor gene, from rose flowers. Quantitative RT‐PCR and GUS reporter analyses showed that <italic>RhHB1</italic> 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<sub>3</sub> delayed the process. However, silencing of <italic>RhHB1</italic> delayed the ABA‐ or ethylene‐mediated senescence, and resulted in higher petal anthocyanin levels and lower expression of <italic>RhSAG12</italic>. Moreover, treatment with paclobutrazol, an inhibitor of GA biosynthesis, repressed these delays. In addition, silencing of <italic>RhHB1</italic> blocked the ABA‐ or ethylene‐induced reduction in expression of the GA20 oxidase encoded by <italic>RhGA20ox1</italic>, a gene in the GA biosynthetic pathway. Furthermore, RhHB1 directly binds to the <italic>RhGA20ox1</italic> promoter, and silencing of <italic>RhGA20ox1</italic> promoted petal senescence. Eight senescence‐related genes showed substantial differences in expression in petals after treatment with GA<sub>3</sub> 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.</p> </abstract>