Zhao Zhuofan

A preliminary identification of Rf*-A619, a novel restorer gene for CMS-C in maize (Zea mays L.)

C-type cytoplasmic male sterility (CMS-C) is widely utilized for hybrid maize seed production. However, genetic mechanisms underlying the fertility restoration are very complicated. At present, there is a divergence on the number of fertility restorer genes in maize inbred line A619 for CMS-C. To further elucidate the restoring mechanism of A619, we used genetic analysis and molecular markers to confirm the restorer genes of maize inbred line A619 for C-type male sterile line C48-2 in this study. Firstly, the fertility segregations of (C48-2 × A619)F2 populations were investigated under three environments during 2013–2015. The segregation ratio of fertile and sterile plants in the F2 population fit to 15:1 via chi-square test and this result suggested that there are two dominant restorer genes in A619 for CMS-C, i.e., Rf4 and a novel gene named Rf*-A619. Next, based on the sequence differences between Rf4 and its recessive allelic rf4, a novel dominant marker F2/R2 was developed and validated to genotyping Rf4 in the F2 population. Through genotypic analysis, we found that there were a certain amount of fertile individuals without Rf4 which accounted for 3/16 in the F2 population via chi-square test at the 0.05 level. These results provided another proof to sustain that the inbred line A619 contains one additional restorer gene for CMS-C fertility restoration except Rf4. At last, we used one SSR marker which is tightly linked with the dominant restorer gene Rf5 to analyze those fertile plants without Rf4 in the F2 population. The PCR amplification results showed that Rf*-A619 is not allelic to Rf5 but a novel restorer gene for CMS-C. These results not only provide a basis for the mapping and characterization of a novel restorer gene but also give a new insight into the mechanism of CMS-C fertility restoration.

Research progress on mechanisms of male sterility in plants based on high-throughput RNA sequencing

Male sterility is defined as failing to produce functional pollen during stamen development in plants, and it plays a crucial role in plant reproductive research and hybrid seed production in utilization of crop heterosis. High throughput RNA sequencing (RNA-seq) has been used widely in the study of different fields of life science, as it readily detects all the mRNA and non-coding RNA in cells. Recently, RNA-seq has been reported to be applied in different species and kinds of pollen abortion types in plants, which has contributed to the understanding of the molecular mechanism and metabolic networks of male sterility at the transcription level. In this review, we summarize research progress on the mechanisms of male sterility in plants, focusing on RNA-seq analysis encompassing strategies of RNA library construction, differentially expressed genes and functional characteristics of noncoding RNAs involved in stamen abortion. Furthermore, we also discuss application of transcriptome sequencing technology to elucidate pollen abortion mechanisms and map fertility-related genes. We hope to provide references to the study of male sterility in plants.