OsGAMYBL2 is required for pollen maturation and germination in rice

The reproductive development process of rice is not only important for basic developmental biology research, but also of great benefit to production practice. However, current understanding of the reproductive growth process is relatively limited, especially in the later stages of development. Here we report that OsGAMYBL2, a homologous gene of GAMYB, is required for pollen maturation and germination in rice, and that loss of function of OsGAMYBL2 leads to male sterility in rice. We generated three alleles of OsGAMYBL2 knockout mutants using CRISPR/Cas9 system, all of them lost fertility when grown in the paddy field. Semi-section and electron microscopy observations revealed that there are no visible morphological changes in the outer and inner surfaces of anther and in the surface of mature pollens between mutants and wild type. However, pollens at late developmental stages exhibited much lighter pollen viability staining and some of them shriveled. In vitro and in vivo germination experiments showed that mutant pollens fail to germinate, leading to abnormal pollen tube formation and subsequent defective pollination. Furthermore, we observed that as compared with high temperature at 30 ​°C, low-temperature at 22 ​°C affects less on osgmybl2 fertility. Collectively, we proposed that OsGAMYBL2 is likely involved in the regulation of starch accumulation during later pollen development with a thermal-sensitive way, which improves our understanding on the reproductive development in plants.