Genome-Wide Characterization, Stress-Responsive Expression, and QTLome Integration of the DUF1645 Gene Family in Rice (Oryza sativa L.)
TL;DR
The OsDUF1645 family exhibits substantial functional diversification, supported by distinct regulatory architectures, expression profiles, and QTL associations, which provide a framework for prioritizing OsDUF1645 candidates for functional validation and their potential application in molecular breeding and development of climate-resilient rice cultivars.
Abstract
Background: Domain of Unknown Function 1645 (DUF1645) is a conserved but poorly characterized plant gene family whose evolutionary history and roles in stress adaptation remain unclear. We performed an integrated genomic, evolutionary, transcriptomic, and Quantitative Trait Locus (QTL) characterization of the DUF1645 family in rice (Oryza sativa). Methods and Results: We identified 14 intronless, non-redundant OsDUF1645 genes distributed across eight chromosomes. Phylogenetic and collinearity analyses suggested that family expansion within Poaceae involved ancestral segmental and localized tandem duplication events. Promoter analysis identified stress- and phytohormone-responsive cis-acting elements, including ABRE, MBS, and MeJA-associated motifs. Public transcriptome datasets revealed diverse OsDUF1645 expression patterns under abiotic and hormonal treatments. Integration with the Quantitative Trait Loci Annotation Rice Online (Q-TARO) QTLome identified physical co-localization of multiple OsDUF1645 loci with stress- and agronomic-trait QTLs, including salinity-, drought-, root architecture-, and water-deficit-associated regions. On Chromosome 1, OsDUF1645.1, OsDUF1645.2, OsDUF1645.3, and OsDUF1645.4 overlapped QTL intervals associated with salinity-related physiological traits, including Na+ uptake and Na+ balance, and drought-related root traits. On Chromosome 5, the tandemly arranged OsDUF1645.8, OsDUF1645.9, and OsDUF1645.10 co-localized with QTLs related to root architecture and water-deficit responses. qRT-PCR validation under salinity, osmotic stress, and cadmium exposure confirmed distinct stress-responsive expression profiles; OsDUF1645.6 exhibited broad multi-stress responsiveness, whereas OsDUF1645.3 was downregulated under several conditions. Conclusions: The OsDUF1645 family exhibits substantial functional diversification, supported by distinct regulatory architectures, expression profiles, and QTL associations. These findings provide a framework for prioritizing OsDUF1645 candidates for functional validation and their potential application in molecular breeding and development of climate-resilient rice cultivars.