Identification of rice DUF1719 gene family and analysis of alkaline tolerance function of OsDUF1719.8.

Alkaline stress severely constrains the physiological metabolism and growth and development of rice through high pH and ionic toxicity. Domains of unknown function (DUF) play significant roles in plant stress responses. However, the function of the DUF1719 family (PF08224) in rice has not been reported and further research is needed. This study systematically identified the OsDUF1719 gene family in rice and investigated the function of OsDUF1719.8 under alkaline stress. The results demonstrate that the rice DUF1719 family comprises 13 protein members, all containing the PF08224 domain. It is predicted that this domain may play a role in ATPase activation. Evolutionary analysis divided DUF1719 proteins from eight grass species into six subgroups, with highly conserved gene structures, motifs, and tertiary architectures within each subgroup. Promoter analysis indicated enrichment of stress- and hormone-responsive elements, implying broad involvement in stress regulation. Expression analysis revealed that several genes, including OsDUF1719.5 and OsDUF1719.8, were upregulated under multiple abiotic stresses. Notably, OsDUF1719.8 was strongly induced during early alkaline stress. Consequently, we further analyzed the function of OsDUF1719.8 in the rice alkaline stress response. The results demonstrate that overexpression of OsDUF1719.8 enhanced rice alkaline tolerance, whereas knockout mutants exhibited stress sensitivity. OsDUF1719.8 enhances rice tolerance to alkaline stress by coordinately regulating reactive oxygen species metabolism, promoting the accumulation of osmotic adjustment compounds, and modulating ion homeostasis. This study provides the first systematic identification of the DUF1719 family and elucidates the function of OsDUF1719.8 in positively regulating rice alkaline tolerance, offering a novel gene for alkali-tolerant molecular breeding of rice.