Male reproductive development is necessary for the alternation of the life cycle in angiosperms. Due to functional redundancy of genes in the allohexaploid genome of common wheat, there are only two loci of recessive nuclear genic male sterility (GMS) mutations reported in wheat. Here, we report a new wheat recessive GMS gene, TaMs6, which encodes a GDSL esterase/lipase protein (GELP). TaMs6 is predominantly expressed in the anther during meiosis and the unicellular microspore stage, especially in meiotic cells (MCs), dyad cells, tapetum, and middle layer. The loss of TaMs6 function leads to male sterility, likely due to the downregulation of some pollen development-related genes and changes in lipid composition during meiosis. The ms6 mutant and Ms6 gene can potentially be utilized for developing commercial-scale hybrid wheat breeding systems. We also systematically analyzed the GELP gene family in wheat, providing a comprehensive understanding of the TaGELP family and offering valuable references for in-depth genetic studies. Additionally, we discovered the nonallelic noncomplementation of two male-sterile mutants, which presents an interesting and promising research direction.

Rice is one of the most important food crops in the world. Weeds seriously affect the rice yield and grain quality. In recent years, there are tremendous progresses in the research and application of herbicide-resistant genes in rice worldwide. This article reviews the working mechanisms of six herbicides (glyphosate, glufosinate, acetolactate synthase inhibitor herbicides, acetyl-CoA carboxylase inhibitor herbicides, hydroxyhenylpyruvate dioxygenase (HPPD) inhibitor herbicides and dinitroaniline herbicides), the resistance mutations of the corresponding herbicide-target genes, and the herbicide detoxification mechanisms by non-target genes. Examples are provided on herbicide-resistant rice materials obtained by transformation of exogenous resistance genes, by artificial mutagenesis and mutant screening, and by modifying the target genes through gene editing. This paper also introduces the current application of herbicide-resistant rice, points out problems that may be caused by utilization of herbicide resistant rice and solutions to the problems, and discusses the future prospects for the development of herbicide-resistant rice.

The breeding and large-scale application of hybrid rice contribute significantly to the food supply worldwide. Currently, hybrid seed production uses cytoplasmic male sterile (CMS) lines or photoperiod/thermo-sensitive genic male sterile (PTGMS) lines as female parent. Despite huge successes, both systems have intrinsic problems. CMS systems are mainly restricted by the narrow restorer resources that make it difficult to breed superior hybrids, while PTGMS systems are limited by conditional sterility of the male sterile lines that makes the propagation of both PTGMS seeds and hybrid seeds vulnerable to unpredictable climate changes. Recessive nuclear male sterile (NMS) lines insensitive to environmental conditions are widely distributed and are ideal for hybrid rice breeding and production, but the lack of effective ways to propagate the pure NMS lines in a large scale renders it impossible to use them for hybrid rice production. The development of “the third-generation hybrid rice technology” enables efficient propagation of the pure NMS lines in commercial scale. This paper discusses the establishment of “the third-generation hybrid rice technology” and further innovations. This new technology breaks the limitations of CMS and PTGMS systems and will bring a big leap forward in hybrid rice production.

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.

Herbicide resistance in crop plants is valuable for integrated weed management in agriculture. Herbicide resistant rice, in particular, is important to management of weedy rice, a close relative of cultivated rice and a noxious weed prevalent in rice fields that remains challenging to farmers worldwide. Herbicide resistant plants can be obtained through transgenic approach or by mutagenesis of regular plant and screening of mutants with elevated resistance to herbicide. In this study, we conducted ethyl methyl sulfonate mutagenesis (EMS) to elite indica cultivar Huanghuazhan (HHZ) and screened for mutants resistant to imazapic, a herbicide that can inhibit the acetolactate synthase (ALS) in plants. We obtained three mutants of OsALS gene that have not been reported previously in rice. One of the mutants, with Trp₅₄₈ changed to Met (W₅₄₈M), was analyzed in more details in this study. This mutation had no negative effect on the plant physiology and morphology as well as rice yield. Compared with the imidazolinone-resistant mutant S₆₂₇N (Ser₆₂₇ changed to Asn) that has been deployed for Clearfield rice development, W₅₄₈M mutant showed high levels of resistance to a broad spectrum of five families of ALS-inhibiting herbicides, in addition to a higher level of resistance to herbicides of the imidazolinone family. The herbicide-resistance was stably inherited by crossing into other rice lines. Thus, the W₅₄₈M mutation provides a valuable resource for breeding of herbicide resistant rice and weed management.

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.