Genome-Wide Identification, Characterization, and Expression Analysis of the MYB-R2R3 Gene Family in Black Pepper (Piper nigrum L.)

Black pepper (<i>Piper nigrum</i> L.), a prominent spice crop, known as the "king of spices", originated from India. The growth and development of black pepper are influenced by various environmental conditions. MYB transcription factors play a crucial role in controlling metabolic processes, abiotic stress management, and plant growth and development. In this study, we identified 160 <i>PnMYB</i> transcription factors in the black pepper genome. Phylogenetic analysis was performed using 125 R2R3-MYB proteins from black pepper and <i>Arabidopsis thaliana</i>, resulting in the mapping of 20 groups on the phylogenetic tree, each containing members from both species. Most members of the <i>PnMYB</i> family possess two introns, and motif 3 and motif 4 are conserved in all members. The number of genes on each chromosome ranges from 1 to 10. Collinear analysis indicated the creation of new members through gene fragments and tandem replication. The Ka/Ks ratio indicated that purifying selection and positive selection acted on <i>PnMYB</i> of pepper. The majority of pepper <i>PnMYB</i> family members were in the nucleus. Significant differences in gene expression levels were observed between different species and infection periods when <i>Piper nigrum</i> L. and <i>Piper flaviflorum</i> were infected with <i>Phytophthora capsici</i>. These findings are valuable for future studies on the biological role and molecular mechanism of the <i>PnMYB</i> gene.