title: A subclass of HSP70s regulate development and abiotic stress responses in Arabidopsis thaliana.
abstract: Members of the HSP70 family function as molecular chaperones to maintain cellular homeostasis and help plants cope with environmental stimuli. However, due to functional redundancy and lack of effective chemical inhibitors, our knowledge of functions of individual HSP70s has remained limited. Here, we confirmed a subclass of HSP70s, including HSP70-1, -2, -3, -4, and -5, localized to the cytosol and nucleus in Arabidopsis thaliana. Histochemical analyses of promoter:GUS reporter lines showed that HSP70-1, -2, -3, and -4 genes were widely expressed, but HSP70-5 was not. In addition, individual HSP70 showed not only similar but also distinct transcriptions when treated by different abiotic stresses and phytohormones. No apparent phenotype was observed when individual HSP70 genes were overexpressed or knocked-out/down, but the double mutant hsp70-1 hsp70-4 and triple mutant hsp70-2 hsp70-4 hsp70-5 plants exhibited developmental phenotypes with shortened specific growth periods, curly and round leaves, twisted petioles, thin stems, and short siliques. Moreover, both mutants were hypersensitive to heat, cold, high glucose, salt and osmotic stress, but hyposensitive to abscisic acid. Genes related to flowering, and the cytokinin, brassinosteroid, and abscisic acid signaling pathways were differentially expressed in both mutants. Our studies suggest that, the individual HSP70 possibly performs both redundant and specific functions with the other members in the cytosolic/nuclear HSP70 subclass, and apart from enabling plants to cope with abiotic stresses, this subclass of cytosolic/nuclear HSP70 proteins also participates in diverse developmental processes and signaling pathways.
authors.affiliation: State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China.
authors.forename: Linna
authors.initials: L
authors.lastname: Leng
authors.affiliation: State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Liang
authors.affiliation: State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China.
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China.
authors.forename: Yuhan
authors.initials: Y
authors.lastname: Hao
authors.affiliation: College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Xuelu
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Genetic Engineering and Institute of Plant Biology, School of Life Sciences, Fudan University, Room 421, School of Life Science Building, No. 2005, Songhu Road, Shanghai, 200438, China. weisu@fudan.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Su
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D010937:Plant Growth Regulators; D013312:Stress, Physiological
chemical_list: D029681:Arabidopsis Proteins; D018840:HSP70 Heat-Shock Proteins; D010937:Plant Growth Regulators
keywords: Abiotic stress; Arabidopsis thaliana; Development; HSP70; Signaling pathway