Genome-Wide Identification of the Light-Harvesting Chlorophyll a/b Binding Protein Gene Family in Pyrus bretschneideri and Their Transcriptomic Features under Drought Stress

Light-harvesting chlorophyll a/b binding (Lhc) proteins play a key role in the efficiency of the photosynthetic system of plants and participate in the regulation of plant growth, development, and the response to abiotic stress. In this study, 28 PbrLhc genes of the family were identified in the pear Pyrus bretschneideri genome database, which were distributed on 25 of the 27 chromosomes. Phylogenetic relationship analysis demonstrated that PbrLhc proteins could be divided into five subfamilies. Using MEME Suite, PlantRegMap, and Softberry, the conserved motifs, transcription binding sites, and predicated location of all PbrLhc proteins, respectively, were determined. A collinearity relationship using MCScanX software showed that there was a collinearity relationship between different PbrLhc genes. Using the hierarchical clustering method to develop a heat map of gene expression, five genes were found to be down-regulated under irrigation treatment and up-regulated under drought treatment; seven genes were up-regulated under irrigation treatment and down-regulated under drought treatment. Finally, the results of these analyses will provide theoretical basis for future study on the function and differential expression of PbrLhc genes in response to drought stress.