title: RhHB1 mediates the antagonism of gibberellins to ABA and ethylene during rose (Rosa hybrida) petal senescence.
abstract: 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 GA3 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 GA3 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.
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China.
authors.forename: Peitao
authors.initials: P
authors.lastname: Lü
authors.forename: Changqing
authors.initials: C
authors.lastname: Zhang
authors.forename: Jitao
authors.initials: J
authors.lastname: Liu
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Liu
authors.forename: Guimei
authors.initials: G
authors.lastname: Jiang
authors.forename: Xinqiang
authors.initials: X
authors.lastname: Jiang
authors.forename: Muhammad Ali
authors.initials: MA
authors.lastname: Khan
authors.forename: Liangsheng
authors.initials: L
authors.lastname: Wang
authors.forename: Bo
authors.initials: B
authors.lastname: Hong
authors.forename: Junping
authors.initials: J
authors.lastname: Gao
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D000595:Amino Acid Sequence; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism; D004336:Drug Antagonism; D005030:Ethylenes / Q000494:pharmacology*; D035264:Flowers / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D020868:Gene Silencing; D005875:Gibberellins / Q000494:pharmacology*; D007656:Ketoglutaric Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D027826:Rosa / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014230:Triazoles / Q000494:pharmacology
chemical_list: D005030:Ethylenes; D005875:Gibberellins; D007656:Ketoglutaric Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014230:Triazoles; C053370:paclobutrazol; D000040:Abscisic Acid; D049308:Dioxygenases
keywords: RhHB1; Rosa hybrida; abscisic acid; ethylene; flower senescence; gibberellins