The Rice Small Auxin-Up RNA Gene Regulates Seed Vigor via Sugar Pathway during Early Seed Germination.

Seed vigor affects seed germination and seedling emergence, and therefore is an important agronomic trait in rice. Small auxin-up RNAs () function in a range of developmental processes, but their role in seed vigor remains unclear. Here, we observed that disruption of resulted in reduced germination rates and low seed uniformity in early germination. Expression of was higher in mature grains and early germinating seeds. RNA-seq analysis revealed that modulated seed vigor by affecting the mobilization of stored reserves during germination. Disruption of increased the soluble sugar content in dry mature grains and seeds during early germination. OsSAUR33 interacted with the sucrose non-fermenting-1-related protein kinase OsSnRK1A, a regulator of the sugar signaling pathway, which influences the expression of sugar signaling-related genes during germination. Disruption of increased sugar-sensitive phenotypes in early germination, suggesting OsSAUR33 likely affects seed vigor through the sugar pathway. One elite haplotype of associated with higher seed vigor was identified mainly in accessions. This study provides insight into the effects of OsSAUR33 on seed vigor in rice.