A Killer-Protector System Regulates Both Hybrid Sterility and Segregation Distortion in Rice

• Published in: Science (American Association for the Advancement of Science) Vol. 337; no. 6100; pp. 1336 - 1340
• Main Authors: Yang, Jiangyi, Zhao, Xiaobo, Cheng, Ke, Du, Hongyi, Ouyang, Yidan, Chen, Jiongjiong, Qiu, Shuqing, Huang, Jianyan, Jiang, Yunhe, Jiang, Liwen, Ding, Jihua, Wang, Jia, Xu, Caiguo, Li, Xianghua, Zhang, Qifa
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 14-09-2012; The American Association for the Advancement of Science
• Subjects: Agricultural biotechnology; Agricultural production; Agronomy. Soil science and plant productions; Alleles; Amino Acid Sequence; Biological and medical sciences; Chimera - genetics; Classical and quantitative genetics. Population genetics. Molecular genetics; Crops; Endoplasmic Reticulum Stress - genetics; Fundamental and applied biological sciences. Psychology; Gametes; Generalities. Genetics. Plant material; Genetic loci; Genetics and breeding of economic plants; Genotypes; Germ Cells, Plant - metabolism; Hybridity; Molecular Sequence Data; Open Reading Frames - genetics; Oryza - cytology; Oryza - genetics; Plant fertility; Plant Infertility - genetics; Plant reproduction; Population genetics; Proteins; Rice; Segregation distortion; Spikelets; Monocotyledones; Reproductive isolation; Segregation; Hybrid; Distortion; Population genetics; Sterility; Cereal crop; Open reading frame; Oryza sativa; Gene flow; Gene; Gramineae; Fertility; Angiospermae; Spermatophyta; Locus
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1223702

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.