Molecular characterization, expression pattern and function analysis of the rice OsDUF866 family

Domain-of-unknown function (DUF) proteins represent a number of gene families with no functional annotation in the Pfam database. So far, the DUF866 family has not been characterized, and no member has been functionally studied. In this study, we uncovered and analysed four OsDUF866 (OsDUF866.1–OsDUF866.4) family members in rice Nipponbare, in which three distinct motifs were identified. The expression of OsDUF866 family in nine tissues was examined by real-time polymerase chain reaction (PCR), and the highest expression of four genes members was found in embryos at 14 days after flowering. We performed real-time PCR to examine the expression of OsDUF866 family under abiotic stress and abscisic acid (ABA) treatment conditions. The expression level of OsDUF866.1 displayed significant decrease under drought and salt conditions, while significant increase under heat conditions. The expression level of OsDUF866.2 displayed significant decrease under drought conditions. The expression level of OsDUF866.3 was significantly elevated under drought and cold, while lowered under heat conditions. The expression level of OsDUF866.4 was increased under cold and heat conditions, while decreased under drought conditions. Interestingly, the expression level of OsDUF866 members was approximately constant under ABA treatment conditions. Overexpression of OsDUF866.1 in Escherichia coli could enhance cell viability and significantly improve the resistance to heat stress conditions. The results may provide new insights into the function of OsDUF866 family in rice.