title: A rice dihydrosphingosine C4 hydroxylase (DSH1) gene, which is abundantly expressed in the stigmas, vascular cells and apical meristem, may be involved in fertility.
abstract: Dihydrosphingosine C4 hydroxylase is a key enzyme in the biosynthesis of phytosphingosine, a major constituent of sphingolipids in plants and yeasts. The rice genome contains five homologue genes for dihydrosphingosine C4 hydroxylase, DSH1-DSH5, whose gene products show high degrees of homology to the yeast counterpart, SUR2. Among them, expression of DSH1, DSH2 and DSH4 was detected, and DSH1 and DSH4 complement the yeast sur2 mutation. The DSH1 gene was specifically and abundantly expressed in vascular bundles and apical meristems. In particular, very strong expression was detected in the stigmas of flowers. Repression of DSH1 expression by the antisense gene or RNA interference (RNAi) resulted in a severe reduction of fertility. In the transformants in which DSH1 expression was suppressed, significantly increased expression of DSH2 was found in leaves but not in pistils, suggesting that there was tissue-specific correlation between DSH1 and DSH2 expression. Our results indicate that the product of DSH1 may be involved in plant viability or reproductive processes, and that the phenotype of sterility is apparently caused by loss of function of DSH1 in the stigma. It is also suggested that there is a complex mechanism controlling the tissue-specific expression of the DSH1 gene.
authors.affiliation: Department of Biological Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Imamura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kusano
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Kajigaya
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Ichikawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shimada
mesh_terms: D000595:Amino Acid Sequence; D005298:Fertility / Q000235:genetics; D035264:Flowers / Q000201:enzymology* / Q000235:genetics; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D017403:In Situ Hybridization; D018519:Meristem / Q000201:enzymology* / Q000235:genetics; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009154:Mutation; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D006899:Mixed Function Oxygenases; D013110:Sphingosine; C005682:safingol