TaMs1 encodes a non-specific lipid transfer protein (nsLTP) and is required for pollen development in wheat. Although MS1 is a Poaceae-specific gene, the roles of MS1 genes in other Poaceae plants are unknown, especially in rice and maize. Here, we identified one ortholog in rice (OsLTPg29) and two orthologs in maize (ZmLTPg11 and ZmLTPx2). Similar to TaMs1, both OsLTPg29 and ZmLTPg11 genes are specifically expressed in the microsporocytes, and both OsLTPg29 and ZmLTPg11 proteins showed lipid-binding ability to phosphatidic acid and several phosphoinositides. To determine their roles in pollen development, we created osltpg29 mutants and zmltpg11zmltpx2 double mutants by CRISPR/Cas9. osltpg29, not zmltpg11zmltpx2, is defective in pollen development, and only OsLTPg29, not ZmLTPg11, can rescue the male sterility of tams1 mutant. Our results demonstrate that the biological function of MS1 in pollen development differs in the evolution of Poaceae plants.

The breeding of herbicide-resistant wheat varieties has helped control weeds in wheat fields economically and effectively. Imidazolinone (IMI) herbicides are popular as they have low toxicity in mammals, are effective at small doses, and exhibit broad-spectrum herbicidal action in the field. Therefore, the isolation and genetic and molecular characterization of IMI-resistant wheat mutants will enhance weed management in wheat fields. In the present study, 352 IMI-resistant plants were isolated by genetic screening from a mutant pool prepared by EMS-based random mutagenesis. Cloning of the mutated genes from the IMI-resistant plants indicated that ten taals alleles had been isolated, and mutation in one of three TaALS homolog genes conferred IMI resistance, and such a mutation is a dominant trait. Further analysis showed that taals-d exhibited the greatest IMI resistance, whereas taals-b exhibited the weakest resistance to IMI among three homologous taals mutants. In terms of IMI resistance, the taals triple mutant was stronger than the taals double mutants, and the taals double mutants were stronger than the single mutants, indicating a dose-dependent effect of the TaALS mutation on IMI resistance in wheat. Biochemical analysis indicated that the mutation in TaALS increased the tolerance of TaALS to inhibition by IMI. Our work details the genetic and molecular characterization of als wheat mutants, provides a foundation for understanding IMI resistance and breeding wheat varieties with herbicide resistance, and indicates that genetic screening using a mutagenized pool is an effective and important means of breeding crops with additional desired agricultural traits.

The characterization of agronomically important genes has great potential for the improvement of wheat. However, progress in wheat genetics and functional genomics has been impeded by the high complexity and enormous size of the wheat genome. Recent advances in genome sequencing and sequence assembly have produced a high-quality genome sequence for wheat. Here, we suggest that the strategies used to characterize biological mechanisms in model species, including mutant preparation and characterization, gene cloning methods, and improved transgenic technology, can be applied to wheat biology. These strategies will accelerate progress in wheat biology and promote wheat breeding program development. We also outline recent advances in wheat functional genomics. Finally, we discuss the future of wheat functional genomics and the rational design-based molecular breeding of new wheat varieties to contribute to world food security.