Identification of hub genes regulating seed germination viability in soybean via comparative transcriptome analysis...

Soybean [Glycine max (L.) Merr.] is the most common leguminous crop and provides protein and oil for human edible, animal feed, industrial and new energy across the world. The abundant oil and protein cause it more difficult to store than cereal seeds. Seed germination viability is a crucial foundation for soybean storage life and seedling establishment, while its regulatory factors remains largely unexplored.

In this study, by compared germination percentage (GP) of 107 soybean accessions after natural aging for 18, 30 and 42 months, we identified 13 storage-tolerant and 9 storage-sensitive genotypes. Moreover, 6 high vigor genotypes and 4 low vigor genotypes were screened through 4 days of artificial aging treatment in 124 soybean accessions. The viability curves and physiological indicators indicate that high germination viability genotypes could delay the critical node (CN) of seeds by increasing antioxidant enzyme activity. To elucidate the expression profile differences of soybean accessions with contrasting seed germination viability, we generated the transcriptomes from storage-tolerant genotype Manokin (Ma) and storage-sensitive genotype Xiaoheidou (X) that were naturally aged for 18 and 30 months, as well as the high vigor genotype MN0201 (MN) and low vigor genotype Yiwohou (Y) that were artificially aged for 0, 3, 4, and 5 days. Comparative transcriptome and WGCNA analysis showed that genes clustered in the mediumpurle2 module may be involved in seed germination viability. Tissue-specific expression analysis and transcriptional accumulation during seed germination were further employed to assess hub genes, of which the expression characteristics and natural variation of GmHSP17.7B concerned to seed germination viability.

Through screening of soybean genotypes with contrasting seed germination viability from natural populations and comparative transcriptome analysis, we elucidated the antioxidant capacity and expression profile changes during seed deterioration, which will provide worthy genotype resources and targets for efficient improvement of soybean seed vigor.