Abstract
Soybean (Glycine max) provides vegetable oils and proteins for human consumption. Its production depends on seeds and other production-related agronomic traits. How the seed traits are regulated in soybean remains largely unclear. In this study, we identified a miR172a-ERF416/413 module for the regulation of seed traits. The miR172a can cleave the targets ERF416 and ERF413 to affect the downstream gene expression for the reduction of soybean seed size and weight. Both the MIR172a-overexpressing transgenic soybean plants and the erf416/413 mutants produced smaller seeds than the control. Consistently, the ERF416-overexpressing transgenic soybean plants generated larger seeds. ERF416 and ERF413 were directly targeted to the promoter of GmKIX8-1 and GmSWEET10a to regulate their gene expression for seed size/weight control. Interestingly, the erf416/413 mutants showed higher seed yield per plant and higher total seed fatty acid (FA) content, whereas the MIR172a-transgenic soybean had lower total seed FA content compared with the control cultivar, suggesting that miR172a and ERF416/413 may function in FA accumulation through different pathways. Haplotypes of the ERF416 promoter region were further analyzed and Hap1 was correlated with higher gene expression and higher seed weight, while Hap3 was correlated with higher total seed lipid content. Our study revealed a new module for seed trait control. Manipulation of such alleles should facilitate breeding for high-oil and high-yield soybean cultivars.