Genome-wide Identification, Classification, Evolutionary Expansion and Expression of Rboh Family Genes in Pepper (Capsicum annuum L.)

Plant respiratory burst oxidase homolog (Rboh) are key enzymes for reactive oxygen species (ROS) production in plants. They help in resisting adverse environmental conditions and regulating growth and development. To date, many Rboh family members have been identified in plants, but little is known about Rboh genes in pepper. In this study, seven CaRboh genes and six CaRboh genes were identified in ‘Zunla-1′ and ‘CM334′ pepper genomes, respectively. All CaRboh proteins were predicted to localize to the plasma membrane and were divided into five subfamilies by comparative phylogenetic analysis. A total of fourteen cis-elements were identified in the promoters of CaRboh genes. Synteny analysis of the Rboh proteins of pepper with those of Arabidopsis, tomato, and potato, led to the identification of several orthologous and paralogous genes, which provided further insight into the diversity of the evolutionary characteristics of genes of this family in other plant species. Besides, the expression profiles revealed that CaRbohA, CaRbohB, and CaRbohD genes were highly expressed in all tissues, while CaRbohC, CaRbohF, and CaRbohG genes were expressed at very low levels. The results of physiological indexes and qRT-PCR showed that CaRbohA, CaRbohB, and CaRbohD genes response to stress by mediates H2O2 and O2•−, and then lead to MDA accumulation, implying that the three genes play an important role in response to abiotic stress. This study has laid a foundation for further understanding of the function of Rboh family genes in pepper.