title: Integration of light and abscisic acid signaling during seed germination and early seedling development.
abstract: Seed germination is regulated by endogenous hormonal cues and external environmental stimuli such as water, low temperature, and light. After germination, the young seedling must rapidly establish its root system and the photoautotrophic capability appropriate to its surrounding environment. Light and the phytohormone abscisic acid (ABA) both regulate seed germination and seedling development, although how light and ABA signals are integrated at the molecular level is not understood. Here, we found that the previously described light-signaling component HY5 also mediates ABA response in seed germination, early seedling growth, and root development in Arabidopsis. HY5 binds to the promoter of the transcription factor ABI5 gene with high affinity and is required for the expression of ABI5 and ABI5-targeted late embryogenesis-abundant genes in seeds. Chromatin immunoprecipitation also indicated that the binding of HY5 to the ABI5 promoter is significantly enhanced by ABA. Overexpression of ABI5 restores ABA sensitivity in hy5 and results in enhanced light responses and shorter hypocotyls in the wild type. Our studies identified an unexpected mode of light and ABA signal integration that may help young seedlings better adapt to environmental stresses.
authors.affiliation: Donald Danforth Plant Science Center, St Louis, MO 63132, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Jingyu
authors.initials: J
authors.lastname: Zhang
authors.forename: Michael M
authors.initials: MM
authors.lastname: Neff
authors.forename: Suk-Whan
authors.initials: SW
authors.lastname: Hong
authors.forename: Huiyong
authors.initials: H
authors.lastname: Zhang
authors.forename: Xing-Wang
authors.initials: XW
authors.lastname: Deng
authors.forename: Liming
authors.initials: L
authors.lastname: Xiong
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D008027:Light; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009997:Osmotic Pressure; D018517:Plant Roots / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D036226:Seedlings / Q000254:growth & development* / Q000378:metabolism*; D012639:Seeds / Q000254:growth & development / Q000378:metabolism; D012680:Sensitivity and Specificity; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C109254:HY5 protein, Arabidopsis; D009687:Nuclear Proteins; D000040:Abscisic Acid; D005947:Glucose