Genome-wide Identification and Analyses of the Rice OsDUF 639 Family

With the advance of sequencing technology, the number of sequenced plant genomes has been rapidly increasing. However, functional study of the genes in these sequenced genomes lags far behind; as a result, many plant proteins in public databases are recognized as proteins with domains of unknown function (DUF). DUF639 is such a protein family that consists of plant proteins with unknown function. In this study, we attempted to uncover the biological functions of eight DUF639 members (OsDUF639.1-OsDUF639.8) in rice Nipponbare. Specifically, using phylogenetic analysis, we classified these proteins into four groups (group I, II, III and IV). Next, to find out whether these proteins have tissue-specific expression preference, we examined the expression of all these proteins in 15 distinct rice tissues. We found that OsDUF639.3 was preferentially expressed in grain tissues. The expression of these eight proteins under various abiotic stress was also examined. The results indicated that the expression of OsDUF639.6 remained unchanged approximately under various abiotic stress conditions, while under heat conditions, the expression of OsDUF639.1, OsDUF639.2, OsDUF639.3, OsDUF639.4 and OsDUF639.7 was significantly elevated. Furthermore, we found that overexpression of OsDUF639.1 and OsDUF639.4 in E. coli may significantly improve resistance to heat, whereas overexpression of OsDUF639.2, OsDUF639.3 and OsDUF639.7 do not have a similar effect. In conclusion, our results suggest that DUF639 proteins may have different tissue-specific expression and diversified functions in rice, with some of them possibly contributing to heat resistance. © 2018 Friends Science Publishers