title: Functional characterization of BnHSFA4a as a heat shock transcription factor in controlling the re-establishment of desiccation tolerance in seeds.
abstract: Desiccation tolerance (DT) is the crucial ability of seeds to resist desiccation. However, the regulatory mechanisms of seed DT are not fully understood. In this study, two heat shock cis-elements (HSEs) were identified in the Brassica napus galactinol synthase (BnGolS1) promoter and shown to bind the heat shock transcription factor A4a (BnHSFA4a). Transcriptional expression of BnHSFA4a was induced at the early stage of DT acquisition, prior to increased BnGolS1 activity and galactinol production. Ectopic overexpression of BnHSFA4a (oxBnHSFA4a) in Arabidopsis enhanced DT, particularly during DT re-establishment. OxBnHSFA4a up-regulated the expression of GolS1, GolS2, and raffinose synthase 2 (BnRS2) in Arabidopsis and increased the enzymatic activity of GolS and RS and the concentration of raffinose family oligosaccharides (RFOs). Additionally, the overexpression lines exhibited increased antioxidant abilities. In contrast, the Arabidopsis mutant athsfa4a was more sensitive to dehydration, showing decreases in the efficiency of DT re-establishment, RFO contents, and oxidation resistance. Complementation analysis indicated that DT was rescued in athsfa4a/BnHSFA4a seeds to similar levels compared with those of Col-0. Taken together, these results indicated that BnHSFA4a probably functions in the regulation of GolS expression and activity, and activation of the antioxidative system and other stress response factors to improve DT.
authors.affiliation: National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Tsinghua East Road 35, Haidian District, Beijing 100083, PR China.
authors.forename: Sirui
authors.initials: S
authors.lastname: Lang
authors.affiliation: National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Tsinghua East Road 35, Haidian District, Beijing 100083, PR China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Liu
authors.affiliation: National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Tsinghua East Road 35, Haidian District, Beijing 100083, PR China.
authors.forename: Hua
authors.initials: H
authors.lastname: Xue
authors.affiliation: National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Tsinghua East Road 35, Haidian District, Beijing 100083, PR China.
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.affiliation: National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Tsinghua East Road 35, Haidian District, Beijing 100083, PR China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D029688:Brassica napus / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D003890:Desiccation; D005700:Galactosyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D000076249:Heat Shock Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D000076249:Heat Shock Transcription Factors; D010940:Plant Proteins; D005700:Galactosyltransferases
keywords: Antioxidant system; DT re-establishment; desiccation tolerance (DT); galactinol synthase (GolS); heat shock transcription factor (HSF); raffinose family oligosaccharide (RFO).