title: Arabidopsis Small Rubber Particle Protein Homolog SRPs Play Dual Roles as Positive Factors for Tissue Growth and Development and in Drought Stress Responses.
abstract: Lipid droplets (LDs) act as repositories for fatty acids and sterols, which are used for various cellular processes such as energy production and membrane and hormone synthesis. LD-associated proteins play important roles in seed development and germination, but their functions in postgermination growth are not well understood. Arabidopsis (Arabidopsis thaliana) contains three SRP homologs (SRP1, SRP2, and SRP3) that share sequence identities with small rubber particle proteins of the rubber tree (Hevea brasiliensis). In this report, the possible cellular roles of SRPs in postgermination growth and the drought tolerance response were investigated. Arabidopsis SRPs appeared to be LD-associated proteins and displayed polymerization properties in vivo and in vitro. SRP-overexpressing transgenic Arabidopsis plants (35S:SRP1, 35S:SRP2, and 35S:SRP3) exhibited higher vegetative and reproductive growth and markedly better tolerance to drought stress than wild-type Arabidopsis. In addition, constitutive over-expression of SRPs resulted in increased numbers of large LDs in postgermination seedlings. In contrast, single (srp1, 35S:SRP2-RNAi, and srp3) and triple (35S:SRP2-RNAi/srp1srp3) loss-of-function mutant lines exhibited the opposite phenotypes. Our results suggest that Arabidopsis SRPs play dual roles as positive factors in postgermination growth and the drought stress tolerance response. The possible relationships between LD-associated proteins and the drought stress response are discussed.
authors.affiliation: Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea.
authors.forename: Eun Yu
authors.initials: EY
authors.lastname: Kim
authors.affiliation: Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea.
authors.forename: Ki Youl
authors.initials: KY
authors.lastname: Park
authors.affiliation: Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea.
authors.forename: Young Sam
authors.initials: YS
authors.lastname: Seo
authors.affiliation: Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea wtkim@yonsei.ac.kr.
authors.forename: Woo Taek
authors.initials: WT
authors.lastname: Kim
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000595:Amino Acid Sequence; D052179:Antigens, Plant / Q000235:genetics*; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D002473:Cell Wall / Q000378:metabolism; D055864:Droughts; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D066292:Lipid Droplets; D009154:Mutation; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000502:physiology / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics*; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000502:physiology / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D058105:Polymerization; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000502:physiology / Q000648:ultrastructure; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000502:physiology / Q000648:ultrastructure; D013312:Stress, Physiological; D014026:Nicotiana / Q000235:genetics / Q000254:growth & development / Q000502:physiology / Q000648:ultrastructure
chemical_list: D052179:Antigens, Plant; D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins; C119716:SRPP protein, Hevea brasiliensis; D000040:Abscisic Acid