Comprehensive identification and analysis of DUF640 genes associated with rice growth

Protein domains with conserved amino acid sequences and uncharacterized functions are called domains of unknown function (DUF). The DUF640 gene family plays a crucial role in plant growth, particularly in light regulation, floral organ development, and fruit development. However, there exists a lack of systematic understanding of the evolutionary relationships and functional differentiation of DUF640 within the Oryza genus. In this study, 61 DUF640 genes were identified in the Oryza genus. The expression of DUF640s is induced by multiple hormonal stressors including abscisic acid (ABA), cytokinin (CK), ethylene (ETH), and indole-3-acetic acid (IAA). Specifically, OiDUF640-10 expression significantly increased after ETH treatment. Transgenic experiments showed that overexpressing OiDUF640-10 lines were sensitive to ETH, and seedling length was obstructed. Evolutionary analysis revealed differentiation of the OiDUF640-10 gene in O. sativa ssp. indica and japonica varieties, likely driven by natural selection during the domestication of cultivated rice. These results indicate that OiDUF640-10 plays a vital role in the regulation of rice seedling length.