Genome-wide association study reveals the QTLs and candidate genes associated with seed longevity in soybean (Glycine max (L.) Merrill).

BACKGROUND

Soybean is challenged with a problem of poor seed longevity, a complex trait and key target for breeding. Therefore, understanding the genetic basis of seed longevity is of great significance for mining favorable genes and prolonging the seed life. A genome-wide association study (GWAS) was conducted to understand the genetic background of seed longevity over two ageing methods (natural ageing and accelerated ageing) and seasons.

RESULTS

This study evaluated seed longevity traits in a panel of sixty diverse soybean genotypes with different seed coat colors, seed sizes, and agro-morphological traits under natural and accelerated ageing across two seasons. Seed longevity related traits such as seed germination, seedling vigor index-I (SVI-I), seedling vigor index-II (RVI-II), reduction in vigor index-I (RVI-I), and reduction in vigor index-II (RVI-II) were recorded after 12 and 14 months after natural ageing and accelerated ageing during the year 2019 and 2021. Seed germination under natural aging averaged 45.2% (range: 4.8-100%) after 12 months and 38.1% (range: 0.0-90%) after 14 months. Accelerated ageing resulted in germination rates ranging from 0.0 to 80.6% with means of 43.38% and 40.7% in 2019 and 2021, respectively. Significant variability in SVI-I, SVI-II, RVI-I, and RVI-II was observed across genotypes and conditions. GWAS using 29,955 Genotyping-by-sequencing (GBS)-single nucleotide polymorphism (SNP) markers identified 71 significant SNPs linked to seed longevity traits. Chromosomes 1, 4, and 8 harboured common SNPs for seed germination, SVI-I, SVI-II, and RVI-I. QTL hotspots were detected on chromosomes 2 and 8, encompassing multiple SNPs within 189 bp and 19 bp, respectively. Twenty-eight candidate genes were identified, including Glyma20g27840 (encoding a LEA hydroxyproline-rich glycoprotein family) on chromosome 20 for germination and SVI-I, and Glyma08g24630 (encoding ATP-dependent RNA helicase A) on chromosome 8 for germination, SVI-II, and RVI-II. Several candidate genes involved in ROS scavenging, cell regulation, ATP production, metabolism, stress response, and seed development were also associated with seed longevity traits.

CONCLUSIONS

The SNPs associated with many longevity related traits and genes in the present study can be used for soybean breeding and functional studies of seed longevity in soybean after validation using linkage mapping or diverse population.