Knocking out artificially selected gene GmAOC4^H8 improves germination in soybean

Seed germination is an essential stage in the life cycle of flowering plants, influencing the field emergence rates of seeds. Consequently, the role of GmAOC4 in soybean seed germination was investigated in the present study. Results suggested that the chloroplast-localized GmAOC4 exhibited high expression levels in the roots and young pods and during the seed germination stage in soybeans. It was found that GmAOC4 has been artificially selected during soybean domestication and improvement and that GmAOC4^H8 showed repressed seed germination, of which the frequency in landraces and cultivars decreased when compared with wild soybean. Knocking out GmAOC4^H8 via CRISPR/Cas9 led to enhanced germination in gmaoc4 mutants, suggesting its negative regulation on seed germination in soybeans. Additionally, decreased endogenous jasmonic acid (JA) and JA precursor, 12-oxo-phytodienoic acid, were found in gmaoc4 mutants. RNA-seq analyses revealed that 91 and 269 differentially expressed genes (DEGs) were up-regulated and down-regulated in gmaoc4 mutants, respectively. Among these DEGs, three genes were involved in JA biosynthetic and signaling pathways. Our results offer new insights into the mechanism of soybean seed germination regulation by GmAOC4.