The lengths of open reading frame (ORF)100 and ORF29-TrnC GCA , the intronic sequence of rps16 and the transcribed spacer of TrnT UGU -TrnL UAA in chloroplast from different lines of cytoplasmic male sterility (CMS) rice were studied using indica types, japonica types and common wild rice as controls. The results show that the lengths of ORF100 and ORF29-TrnC GCA in CMS lines are similar to those of typical indica. The sequences of the rps16 intron and the TrnT UGU -TrnL UAA spacer in sporophyte sterile types (wild-abortive type, Yinshui type and K type) are almost the same, and they also share a molecular marker of GTTGAG at nucleotide positions 220 -225 in the rps16 intron. Therefore, it is speculated that the source of these three types is the same. In contrast, a gametophyte sterile type, Yuetai A does not contain such a GTTGAG sequence in the rps16 intron and has a unique G at position 595, which may works as a molecular marker distinguishing the sporophyte sterile type from the gametophyte sterile type. Based on the observation that CMS rice has much lower cytoplasmic polymorphism than indica, japonica and wild rice, it is concluded that CMS rice lack cytoplasm diversity. Therefore, it is important to introduce new sources of cytoplasm into hybrid rice.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.