title: Identification of rice ethylene-response mutants and characterization of MHZ7/OsEIN2 in distinct ethylene response and yield trait regulation.
abstract: Ethylene plays essential roles in adaptive growth of rice plants in water-saturating environment; however, ethylene signaling pathway in rice is largely unclear. In this study, we report identification and characterization of ethylene-response mutants based on the specific ethylene-response phenotypes of etiolated rice seedlings, including ethylene-inhibited root growth and ethylene-promoted coleoptile elongation, which is different from the ethylene triple-response phenotype in Arabidopsis. We establish an efficient system for screening and a set of rice mutants have been identified. Genetic analysis reveals that these mutants form eight complementation groups. All the mutants show insensitivity or reduced sensitivity to ethylene in root growth but exhibit differential responses in coleoptile growth. One mutant group mhz7 has insensitivity to ethylene in both root and coleoptile growth. We identified the corresponding gene by a map-based cloning method. MHZ7 encodes a membrane protein homologous to EIN2, a central component of ethylene signaling in Arabidopsis. Upon ethylene treatment, etiolated MHZ7-overexpressing seedlings exhibit enhanced coleoptile elongation, increased mesocotyl growth and extremely twisted short roots, featuring enhanced ethylene-response phenotypes in rice. Grain length was promoted in MHZ7-transgenic plants and 1000-grain weight was reduced in mhz7 mutants. Leaf senescent process was also affected by MHZ7 expression. Manipulation of ethylene signaling may improve adaptive growth and yield-related traits in rice.
authors.affiliation: State Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Ma
authors.forename: Si-Jie
authors.initials: SJ
authors.lastname: He
authors.forename: Kai-Xuan
authors.initials: KX
authors.lastname: Duan
authors.forename: Cui-Cui
authors.initials: CC
authors.lastname: Yin
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Chao
authors.initials: C
authors.lastname: Yang
authors.forename: Qing
authors.initials: Q
authors.lastname: Xiong
authors.forename: Qing-Xin
authors.initials: QX
authors.lastname: Song
authors.forename: Xiang
authors.initials: X
authors.lastname: Lu
authors.forename: Hao-Wei
authors.initials: HW
authors.lastname: Chen
authors.forename: Wan-Ke
authors.initials: WK
authors.lastname: Zhang
authors.forename: Tie-Gang
authors.initials: TG
authors.lastname: Lu
authors.forename: Shou-Yi
authors.initials: SY
authors.lastname: Chen
authors.forename: Jin-Song
authors.initials: JS
authors.lastname: Zhang
mesh_terms: D005030:Ethylenes / Q000378:metabolism*; D064527:Etiolation; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000235:genetics; D009154:Mutation; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics*; D018517:Plant Roots / Q000254:growth & development; D011401:Promoter Regions, Genetic
chemical_list: D005030:Ethylenes; D010940:Plant Proteins; C036216:ethylene; D005966:Glucuronidase
keywords: MHZ7; ethylene-response mutant; rice; senescence.; yield traits