Effects of Space Mutation on Fertility and Genetic Diversity of Sugar Beet Single-Embryo Maintainer Lines

To explore the potential of spaceflight mutagenesis in inducing genetic variation, single-embryo sterile (100% sterility) and maintainer sugar beet lines developed by Heilongjiang University underwent a 6-month spaceflight mutagenesis experiment. Post-flight, seeds were cultivated at Hulan Campus in March 2023. This study aimed to identify molecular alterations in cytoplasmic fertility and genetic diversity caused by space mutagenesis across 96 maintainer lines and select elite germplasm for breeding applications. Cytoplasmic fertility analysis using the TR1 primer confirmed stability (all samples exhibited bands < 750 bp). However, S17 primer screening revealed mutations at binding sites: 50% retained original profiles, 41 lines showed band absence, and 7 displayed novel dual bands. Genetic diversity assessment via 101 polymorphic SSR/InDel markers demonstrated substantial genomic divergence, with cluster analysis indicating shifted genetic distances (average 0.337) among mutant lines. Phenotypic screening further identified candidate mother roots with enhanced disease resistance and agronomic traits. Collectively, these findings validate space mutagenesis as an effective tool for generating heritable genetic variation in sugar beet maintainer lines. This work accelerates the development of improved single-embryo maintainer lines, addressing critical challenges in Chinese sugar beet breeding programmes. The outcomes offer practical resources for cultivating high-yielding varieties, demonstrating the potential of space-induced mutagenesis to advance precision breeding strategies.