Cytoplasmic Effects on the Agronomic and Physiological Traits of Dual‐Purpose Genic Male Sterile Substitution Lines of Rice

Abstract

The two‐line hybrid rice (Oryza sativa L.) system is an effective way for breeding and developing super rice. However, few studies have been conducted on the cytoplasmic effects. In this study, the sterile ZhunS substitution lines were acquired by using ZhunS as the nucleus donor, and rice cultivars from indica, temperate japonica, and tropical japonica subgroups and wild species were used as cytoplasmic donors. The agronomic and physiological traits were analyzed. The results indicated that the cytoplasms and ZhunS nuclei had interaction. The shoot dry weight, grain number per panicle, grain weight per plant, and net photosynthesis rate of substitution line with the cytoplasm from Chaling common wild rice (‘Chaling CWR’) were higher than those of ZhunS, whereas the most of these traits in the substitution line with the cytoplasm from tropical japonica rice ‘Lemont’ were lower. When the substitution lines were crossed with parents, the grain yield of a hybrid of Chaling CWR//ZhunS and 9311 was increased by 5.1% as compared with that of the hybrid between ZhunS and 9311. Therefore, Chaling CWR//ZhunS was an efficient sterile line parent. The entire growth periods of the hybrid combinations of Lemont//ZhunS were shortened by >4 d, thus Lemont//ZhunS could be used as an early‐season line. The results provided new information for the development of novel cytoplasmic sources and promotion of heterosis in two‐line hybrid rice.