title: RICE MORPHOLOGY DETERMINANT encodes the type II formin FH5 and regulates rice morphogenesis.
abstract: Multicellular organisms contain a large number of formins; however, their physiological roles in plants remain poorly understood. Here, we reveal that formin homology 5 (FH5), a type II formin mutated in rice morphology determinant (rmd), plays a crucial role in determining rice (Oryza sativa) morphology. FH5/RMD encodes a formin-like protein consisting of an N-terminal phosphatase tensin (PTEN)-like domain, an FH1 domain, and an FH2 domain. The rmd mutants display a bending growth pattern in seedlings, are stunted as adult plants, and have aberrant inflorescence (panicle) and seed shape. Cytological analysis showed that rmd mutants have severe cell elongation defects and abnormal microtubule and microfilament arrays. FH5/RMD is ubiquitously expressed in rice tissues, and its protein localization to the chloroplast surface is mediated by the PTEN domain. Biochemical assays demonstrated that recombinant FH5 protein can nucleate actin polymerization from monomeric G-actin or actin/profilin complexes, cap the barbed end of actin filaments, and bundle actin filaments in vitro. Moreover, FH5 can directly bind to and bundle microtubules through its FH2 domain in vitro. Our findings suggest that the rice formin protein FH5 plays a critical role in determining plant morphology by regulating actin dynamics and proper spatial organization of microtubules and microfilaments.
authors.affiliation: School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hexin
authors.initials: H
authors.lastname: Tan
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Wanqi
authors.initials: W
authors.lastname: Liang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yuan
authors.forename: Jianping
authors.initials: J
authors.lastname: Hu
authors.forename: Haiyun
authors.initials: H
authors.lastname: Ren
authors.forename: Dabing
authors.initials: D
authors.lastname: Zhang
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D049108:Cell Enlargement; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D008870:Microtubules / Q000378:metabolism; D009154:Mutation; D012275:Oryza / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000254:growth & development
chemical_list: D000199:Actins; D008565:Membrane Proteins; D010940:Plant Proteins