title: A killer-protector system regulates both hybrid sterility and segregation distortion in rice.
abstract: Hybrid sterility is a major form of postzygotic reproductive isolation that restricts gene flow between populations. Cultivated rice (Oryza sativa L.) consists of two subspecies, indica and japonica; inter-subspecific hybrids are usually sterile. We show that a killer-protector system at the S5 locus encoded by three tightly linked genes [Open Reading Frame 3 (ORF3) to ORF5] regulates fertility in indica-japonica hybrids. During female sporogenesis, the action of ORF5+ (killer) and ORF4+ (partner) causes endoplasmic reticulum (ER) stress. ORF3+ (protector) prevents ER stress and produces normal gametes, but ORF3- cannot prevent ER stress, resulting in premature programmed cell death and leads to embryo-sac abortion. Preferential transmission of ORF3+ gametes results in segregation distortion in the progeny. These results add to our understanding of differences between indica and japonica rice and may aid in rice genetic improvement.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Jiangyi
authors.initials: J
authors.lastname: Yang
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Zhao
authors.forename: Ke
authors.initials: K
authors.lastname: Cheng
authors.forename: Hongyi
authors.initials: H
authors.lastname: Du
authors.forename: Yidan
authors.initials: Y
authors.lastname: Ouyang
authors.forename: Jiongjiong
authors.initials: J
authors.lastname: Chen
authors.forename: Shuqing
authors.initials: S
authors.lastname: Qiu
authors.forename: Jianyan
authors.initials: J
authors.lastname: Huang
authors.forename: Yunhe
authors.initials: Y
authors.lastname: Jiang
authors.forename: Liwen
authors.initials: L
authors.lastname: Jiang
authors.forename: Jihua
authors.initials: J
authors.lastname: Ding
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: Caiguo
authors.initials: C
authors.lastname: Xu
authors.forename: Xianghua
authors.initials: X
authors.lastname: Li
authors.forename: Qifa
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D002678:Chimera / Q000235:genetics*; D059865:Endoplasmic Reticulum Stress / Q000235:genetics; D055993:Germ Cells, Plant / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D012275:Oryza / Q000166:cytology / Q000235:genetics*; D051479:Plant Infertility / Q000235:genetics*