Genetic and cytological analysis of male sterile mutant <italic>msm2015-1</italic> in mungbean

Abstract

<p indent=0mm>In China, the low yield per unit has always been a problem in the mungbean industry. The heterosis of mungbean is an effective way to increase yield. The male sterile line is a valuable resource to realize the utilization of hybrid. In this study,⁶⁰Co-γ radiation mutagenesis technology was used to induce male sterile mutants in mungbean, and we gained one mutant named <italic>male sterile mungbean 2015-1</italic> (<italic>msm2015-1</italic>) for the first time. There was no significant phenotype difference between <italic>msm2015-1</italic> and Sulyu 1 during the vegetative growth stage. The floral organ of <italic>msm2015-1</italic> was normal, but the anthers of<italic> msm2015-1</italic> were white and could not crack and disperse powder normally in the flowering stage. In the mature stage, hardly any normal pods grew up. Genetic analysis showed the separation ratio of fertility and sterility in the fertile segregation population was in line with 3:1, indicating that the sterility trait was controlled by a single recessive nuclear gene. Cytological analysis of pollen development revealed that there were few pollen grains of <italic>msm2015-1</italic> attached to mature stigmas. The pollen grains of <italic>msm2015-1 </italic>did not germinate <italic>in vitro</italic>. The cytoplasm of <italic>msm2015-1</italic>’s pollen could not be stained by Alexander dye. Three abortion types showed up when stained by I₂-KI dye: typical abortion, spherical abortion and stained abortion. DAPI staining showed the nuclei of <italic>msm2015-1</italic>’s pollen developed abnormally. Magenta acetate staining indicated that abortion occurred in the early stage of pollen development, while the asymmetry and more anomalous fission of meiosis during the tetrad stage were the main causes of pollen abortion.