The Rice Small Auxin-Up RNA Gene <i>OsSAUR33</i> Regulates Seed Vigor via Sugar Pathway during Early Seed Germination

• Main Authors: Jia Zhao, Wenjun Li, Shan Sun, Liling Peng, Zhibo Huang, Yongqi He, Zhoufei Wang
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: International Journal of Molecular Sciences
• Subjects: rice; seed vigor; small auxin-up RNA; sugar pathway
• Online Access: https://www.mdpi.com/1422-0067/22/4/1562
• ISSN: 1661-6596; 1422-0067

Seed vigor affects seed germination and seedling emergence, and therefore is an important agronomic trait in rice. Small auxin-up RNAs (<i>SAURs</i>) function in a range of developmental processes, but their role in seed vigor remains unclear. Here, we observed that disruption of <i>OsSAUR33</i> resulted in reduced germination rates and low seed uniformity in early germination. Expression of <i>OsSAUR33</i> was higher in mature grains and early germinating seeds. RNA-seq analysis revealed that <i>OsSAUR33</i> modulated seed vigor by affecting the mobilization of stored reserves during germination. Disruption of <i>OsSAUR33</i> 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 <i>OsSAUR33</i> increased sugar-sensitive phenotypes in early germination, suggesting OsSAUR33 likely affects seed vigor through the sugar pathway. One elite haplotype of <i>OsSAUR33</i> associated with higher seed vigor was identified mainly in <i>indica</i> accessions. This study provides insight into the effects of OsSAUR33 on seed vigor in rice.