title: Cytochrome P450 family member CYP704B2 catalyzes the {omega}-hydroxylation of fatty acids and is required for anther cutin biosynthesis and pollen exine formation in rice.
abstract: The anther cuticle and microspore exine act as protective barriers for the male gametophyte and pollen grain, but relatively little is known about the mechanisms underlying the biosynthesis of the monomers of which they are composed. We report here the isolation and characterization of a rice (Oryza sativa) male sterile mutant, cyp704B2, which exhibits a swollen sporophytic tapetal layer, aborted pollen grains without detectable exine, and undeveloped anther cuticle. In addition, chemical composition analysis indicated that cutin monomers were hardly detectable in the cyp704B2 anthers. These defects are caused by a mutation in a cytochrome P450 family gene, CYP704B2. The CYP704B2 transcript is specifically detected in the tapetum and the microspore from stage 8 of anther development to stage 10. Heterologous expression of CYP704B2 in yeast demonstrated that CYP704B2 catalyzes the production of omega -hydroxylated fatty acids with 16 and 18 carbon chains. Our results provide insights into the biosynthesis of the two biopolymers sporopollenin and cutin. Specifically, our study indicates that the omega -hydroxylation pathway of fatty acids relying on this ancient CYP704B family, conserved from moss to angiosperms, is essential for the formation of both cuticle and exine during plant male reproductive and spore development.
authors.affiliation: School of Life Science and Biotechnology, Shanghai Jiaotong University, Shanghai 200240, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Franck
authors.initials: F
authors.lastname: Pinot
authors.forename: Vincent
authors.initials: V
authors.lastname: Sauveplane
authors.forename: Danièle
authors.initials: D
authors.lastname: Werck-Reichhart
authors.forename: Patrik
authors.initials: P
authors.lastname: Diehl
authors.forename: Lukas
authors.initials: L
authors.lastname: Schreiber
authors.forename: Rochus
authors.initials: R
authors.lastname: Franke
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Yawei
authors.initials: Y
authors.lastname: Gao
authors.forename: Wanqi
authors.initials: W
authors.lastname: Liang
authors.forename: Dabing
authors.initials: D
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D001704:Biopolymers / Q000096:biosynthesis; D002338:Carotenoids / Q000096:biosynthesis; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D006900:Hydroxylation; D008563:Membrane Lipids / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009154:Mutation; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011058:Pollen / Q000254:growth & development*; D018749:RNA, Plant / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D001704:Biopolymers; D005227:Fatty Acids; D008563:Membrane Lipids; D010940:Plant Proteins; D018749:RNA, Plant; D011994:Recombinant Proteins; C009800:sporopollenin; D002338:Carotenoids; C000521:cutin; D003577:Cytochrome P-450 Enzyme System