Genome-Wide Identification and Expression Pattern Analysis of Dirigent Members in the Genus Oryza

Dirigent (DIR) members have been shown to play essential roles in plant growth, development and adaptation to environmental changes. However, to date, there has been no systematic analysis of the DIR members in the genus . Here, 420 genes were identified from nine rice species to have the conserved DIR domain. Importantly, the cultivated rice species has more DIR family members than the wild rice species. DIR proteins in rice could be classified into six subfamilies based on phylogeny analysis. Gene duplication event analysis suggests that whole genome/segmental duplication and tandem duplication are the primary drivers for genes' evolution in , while tandem duplication is the main mechanism of gene family expansion in the DIR-b/d and DIR-c subfamilies. Analysis of the RNA sequencing data indicates that genes respond to a wide range of environmental factors, and most genes have a high expression level in roots. Qualitative reverse transcription PCR assays confirmed the responsiveness of genes to the undersupply of mineral elements, the excess of heavy metals and the infection of . Furthermore, there exist extensive interactions between DIR family members. Taken together, our results shed light on and provide a research foundation for the further exploration of genes in rice.