OSM1/SYP61: a syntaxin protein in Arabidopsis controls abscisic acid-mediated and non-abscisic acid-mediated responses to abiotic stress.
To identify the genetic loci that control salt tolerance in higher plants, a large-scale screen was conducted with a bialaphos marker-based T-DNA insertional collection of Arabidopsis ecotype C24 mutants. One line, osm1 (for osmotic stress-sensitive mutant), exhibited increased sensitivity to both ionic (NaCl) and nonionic (mannitol) osmotic stress in a root-bending assay. The osm1 mutant displayed a more branched root pattern with or without stress and was hypersensitive to inhibition by Na(+), K(+), and Li(+) but not Cs(+). Plants of the osm1 mutant also were more prone to wilting when grown with limited soil moisture compared with wild-type plants. The stomata of osm1 plants were insensitive to both ABA-induced closing and inhibition of opening compared with wild-type plants. The T-DNA insertion appeared in the first exon of an open reading frame on chromosome 1 (F3M18.7, which is the same as AtSYP61). This insertion mutation cosegregated closely with the osm1 phenotype and was the only functional T-DNA in the mutant genome. Expression of the OSM1 gene was disrupted in mutant plants, and abnormal transcripts accumulated. Gene complementation with the native gene from the wild-type genome completely restored the mutant phenotype to the wild type. Analysis of the deduced amino acid sequence of the affected gene revealed that OSM1 is related most closely to mammalian syntaxins 6 and 10, which are members of the SNARE superfamily of proteins required for vesicular/target membrane fusions. Expression of the OSM1 promoter::beta-glucuronidase gene in transformants indicated that OSM1 is expressed in all tissues except hypocotyls and young leaves and is hyperexpressed in epidermal guard cells. Together, our results demonstrate important roles of OSM1/SYP61 in osmotic stress tolerance and in the ABA regulation of stomatal responses.
Zhu
Jianhua
J
Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-1165, USA.
Gong
Zhizhong
Z
Zhang
Changqing
C
Song
Chun-Peng
CP
Damsz
Barbara
B
Inan
Günsu
G
Koiwa
Hisashi
H
Zhu
Jian-Kang
JK
Hasegawa
Paul M
PM
Bressan
Ray A
RA
D000040:Abscisic Acid / Q000494:pharmacology*; D000222:Adaptation, Physiological / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D003890:Desiccation; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005816:Genetic Complementation Test; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D006878:Hydroxides / Q000494:pharmacology; D018021:Lithium Chloride / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009997:Osmotic Pressure / Q000187:drug effects; D019441:Plant Epidermis / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D011189:Potassium Chloride / Q000494:pharmacology; D017680:Potassium Compounds / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D050765:Qa-SNARE Proteins; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D012987:Soil / Q000032:analysis; D013012:Sorbitol / Q000494:pharmacology; D013314:Stress, Mechanical; D014867:Water / Q000378:metabolism
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D006878:Hydroxides; D008565:Membrane Proteins; D017680:Potassium Compounds; D050765:Qa-SNARE Proteins; C112941:SOS3 protein, Arabidopsis; C472135:SYP61 protein, Arabidopsis; D012987:Soil; C036483:T-DNA; D014867:Water; D012965:Sodium Chloride; D013012:Sorbitol; D011189:Potassium Chloride; D000040:Abscisic Acid; D005966:Glucuronidase; D018021:Lithium Chloride; C029943:potassium hydroxide