Identification of the Arabidopsis dry2/sqe1-5 mutant reveals a central role for sterols in drought tolerance and regulation of reactive oxygen species.
Squalene epoxidase enzymes catalyse the conversion of squalene into 2,3-oxidosqualene, the precursor of cyclic triterpenoids. Here we report that the Arabidopsis drought hypersensitive/squalene epoxidase 1-5 (dry2/sqe1-5) mutant, identified by its extreme hypersensitivity to drought stress, has altered stomatal responses and root defects because of a point mutation in the SQUALENE EPOXIDASE 1 (SQE1) gene. GC-MS analysis indicated that the dry2/sqe1-5 mutant has altered sterol composition in roots but wild-type sterol composition in shoots, indicating an essential role for SQE1 in root sterol biosynthesis. Importantly, the stomatal and root defects of the dry2/sqe1-5 mutant are associated with altered production of reactive oxygen species. As RHD2 NADPH oxidase is de-localized in dry2/sqe1-5 root hairs, we propose that sterols play an essential role in the localization of NADPH oxidases required for regulation of reactive oxygen species, stomatal responses and drought tolerance.
Posé
David
D
Departamento de Biología Molecular y Bioquímica, Universidad de Málaga, 29071 Málaga, Spain.
Castanedo
Itziar
I
Borsani
Omar
O
Nieto
Benjamín
B
Rosado
Abel
A
Taconnat
Ludivine
L
Ferrer
Albert
A
Dolan
Liam
L
Valpuesta
Victoriano
V
Botella
Miguel A
MA
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018744:DNA, Plant / Q000235:genetics; D003681:Dehydration; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D009154:Mutation; D019255:NADPH Oxidases / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics; D054046:Plant Stomata / Q000201:enzymology / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D050603:Squalene Monooxygenase / Q000235:genetics / Q000378:metabolism*; D013261:Sterols / Q000378:metabolism*; D013312:Stress, Physiological
D029681:Arabidopsis Proteins; D018744:DNA, Plant; D017382:Reactive Oxygen Species; D013261:Sterols; D050603:Squalene Monooxygenase; D019255:NADPH Oxidases