Genome-wide identification and expression analysis of JmjC domain-containing gene family related to abiotic stress and photoperiodic treatments in Mung bean (Vigna radiata L.)

Although the JmjC domain-containing histone demethylases displayed a crucial role in maintaining the homeostasis of histone methylation, while the systematic identification and functional researches of JmjC domain-containing gene family have not been conducted in Mung bean (VrJMJ genes). According to the structural characteristics and phylogenetic relationship with their orthologs from Glycine max, Lotus japonicus, Medicago truncatula, Arabidopsis thaliana, and Oryza sativa, a total of 18 VrJMJ genes were identified and divided into four clades (KDM3, KDM5. PKDM8, and PKDM9). Interspecies co-collinearity analysis showed the significant JmjC gene duplication events which have occurred during the Papilionoideae evolution. The exon/intron and domain organization of VrJMJ genes from the same clade (or subclade) were similar. All VrJMJ proteins contained a conserved JmjC domain, meanwhile other essential domains also have been found in some specific VrJMJ proteins which responsible for their functions. Numerous abiotic stress and light response related cis-elements associating with transcriptional regulation that were demonstrated in the promoter regions of VrJMJ genes (ProVrJMJs). Expression profiles of VrJMJ genes in different tissues showed that most genes displayed a tissue-specific expression in roots or leaves. The acronym RT-qPCR results showed that all VrJMJ genes displayed different degrees of abiotic stress (drought, salinity, and cold) and photoperiodic responses. Furthermore, VrJMJ3 and VrJMJ9 were significantly up-regulated after all three abiotic stress treatments, and VrJMJ13 exhibited a potential function in the photoperiodic regulation of Mung bean flowering. These results provided a clear understanding of VrJMJ genes, and laid a theoretical basis for further verification of their potential biological functions of VrJMJ genes.