Soil salt-alkalization seriously impacts crop growth and productivity worldwide. Breeding and applying tolerant varieties is the most economical and effective way to address soil alkalization. However, genetic resources for breeders to improve alkali tolerance are limited in mung bean. Here, a genome-wide association study (GWAS) was performed to detect alkali-tolerant genetic loci and candidate genes in 277 mung bean accessions during germination. Using the relative values of two germination traits, 19 QTLs containing 32 SNPs significantly associated with alkali tolerance on nine chromosomes were identified, and they explained 3.6 to 14.6% of the phenotypic variance. Moreover, 691 candidate genes were mined within the LD intervals containing significant trait-associated SNPs. Transcriptome sequencing of alkali-tolerant accession 132–346 under alkali and control conditions after 24 h of treatment was conducted, and 2565 DEGs were identified. An integrated analysis of the GWAS and DEGs revealed six hub genes involved in alkali tolerance responses. Moreover, the expression of hub genes was further validated by qRT-PCR. These findings improve our understanding of the molecular mechanism of alkali stress tolerance and provide potential resources (SNPs and genes) for the genetic improvement of alkali tolerance in mung bean.

Mung bean (Vigna radiata) plays a significant role in agricultural trade, food processing and utilization, and cropping structure adjustment due to its abundant nutritional components, medicine-food homology, capacity for nitrogen fixation, and soil improvement. The low yield level is a crucial limitation factor in the mung bean industry, while heterosis is an efficient path for increasing crop yields. The flexible utilization of male sterile mung bean materials may solve this pressing demand in the industry. This study identified a completely male-sterile mutant, vrnp 1, in the EMS-mutagenized mung bean cultivar Jilv 10 population, which is controlled by a single recessive nuclear gene. Furthermore, we employed a series of microscopical and histological techniques and observed that the tapetal cells in the vrnp 1 mutant did not perform as expected when reaching stage 8 of anther development, notably exhibiting a delay in entering PCD. This was accompanied by a failure to deposit cell wall components onto the pollen wall, culminating in a complete absence of mature pollen and the manifestation of male sterility. In conclusion, the vrnp 1 mutant could potentially serve as a promising candidate for male sterility in exploiting hybrid vigor in mung bean. Our research may elucidate how the delayed initiation of programmed cell death in tapetal cells contributes to a factor implicated in mung bean male sterility. Furthermore, the phenotypic data collected during pivotal developmental phases may have contributed to a better grasp of mung bean microspores and anther development.