Identification and mapping of a thermo-sensitive genic self-incompatibility gene in maize

Advances in plant male sterility for hybrid seed production: an overview of conditional nuclear male sterile lines and biotechnology-based male sterile systems

Male sterility forms the foundation of hybrid seed production technology in field crops. A variety of genetically controlled male sterility/fertility systems starting with cytoplasmic male sterility (CMS), genic male sterility (GMS) including conditional male sterility and transgenic-based male sterility have been developed and deployed for heterosis breeding over the past century. Here we review environment-sensitive genic male sterility (EGMS) and biotechnology-based male sterility systems and describe the underlying molecular mechanisms. Advances in crop genomics and discovery of a large number of nuclear genes governing anther/pollen development, which are shared across species, are helping design diverse types of male sterile lines suitable for different crop species and situations. In particular, gene editing offers quick and easy route to develop novel male sterility systems for hybrid seed production. We discuss the advantages and challenges of biotechnology-based male sterility systems and present alternative strategies to address concerns of transgenics. Finally, we propose development of functional male sterility systems based on pollen competition as the future area that holds great promise for heterosis breeding.

Environment-sensitive genic male sterility in rice and other plants

Environment-sensitive genic male sterility is a type of male sterility that is affected by both genetic and environmental factors. Environment-sensitive genic male sterile lines are not only used in two-line hybrid breeding but are also good materials for studying plant-environment interactions. In this study we review the research progress on environment-sensitive genic male sterility in rice from the perspectives of epigenetic, transcriptional, posttranscriptional, posttranslational and metabolic mechanisms as well as signal transduction processes. While significant progress has been made in the genetics, gene cloning and understanding of the molecular mechanisms of environment-sensitive genic male sterility in recent years, the relevant regulatory network is still poorly understood in rice. We therefore also review studies of environment-sensitive genic male sterility in Arabidopsis and other crops, hoping to promote research in this field in rice. Finally, we analyse the challenges posed by environment-sensitive genic male sterility and provide corresponding suggestions. This review will contribute towards an understanding the molecular genetics of environment-sensitive genic male sterility and its application in two-line hybrid breeding in rice and other species.