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Rh HB 1 mediates the antagonism of gibberellins to ABA and ethylene during rose ( R osa hybrida ) petal senescence
Author(s) -
Lü Peitao,
Zhang Changqing,
Liu Jitao,
Liu Xiaowei,
Jiang Guimei,
Jiang Xinqiang,
Khan Muhammad Ali,
Wang Liangsheng,
Hong Bo,
Gao Junping
Publication year - 2014
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12494
Subject(s) - petal , abscisic acid , gibberellin , senescence , ethylene , biology , gene silencing , microbiology and biotechnology , biochemistry , botany , gene , catalysis
Summary Rose ( R osa 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 ( GA s) 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 GA 20 oxidase encoded by RhGA20ox1 , a gene in the GA biosynthetic pathway. Furthermore, Rh HB 1 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 Rh HB 1 mediates the antagonistic effect of GA s on ABA and ethylene during rose petal senescence, and that the promotion of petal senescence by ABA or ethylene operates through an Rh HB 1–Rh GA 20ox1 regulatory checkpoint.