Molecular Cloning of Genic Male-Sterility Genes and Their Applications for Plant Heterosis via Biotechnology-based Male-sterility Systems

In this chapter, we summarize the strategies about molecular cloning and functional confirmation of plant genic male-sterility (GMS) genes and their applications for hybrid breeding and seed production via biotechnology-based male-sterility (BMS) systems in crop plants. The main content includes four sections: (1) GMS gene cloning strategies, including forward genetic approaches (e.g., map-based cloning, T-DNA or transposon tagging, and MutMap method) and reverse genetic approaches (e.g., homology-based cloning, anther-specific expression gene screening, and other reverse genetic methods); (2) functional confirmation methods of GMS genes, including transgenic complementation, targeted mutagenesis, allelic mutant test and sequencing, anther spatiotemporal expression analysis, and cytological observation; (3) application value assessment of GMS genes and mutants, such as genetic stability analysis of male sterility controlled by GMS genes under different genetic backgrounds and multiple environments, and genetic effects driven by GMS genes on plant heterosis and analysis of potential linkage with bad traits; (4) development and application of BMS systems based on GMS genes and/or their mutants, including transgenic construct-driven non-transgenic seed systems (e.g., seed production technology (SPT) and multi-control sterility (MCS)), and transgenic male-sterility systems (e.g., roundup hybridization systems (RHS1 and RHS2) and Barnase/Barstar system). Finally, we summarize and provide our perspectives on the studies of GMS genes and development of cost-effective and environment-friendly BMS systems in crop plants.