Analysis of differentially expressed genes in transcriptomes of two pear genotypes under drought stress

Object  To discover key genes related to drought resistance of pear plants based on transcriptome data, and provide a theoretical foundation for the breeding of drought resistant pear varieties.

Method  High through-put transcriptome sequencing by illumina Hi Seq TM 2000 was performed using leaves of ‘Huangguan’ pear (Pyrus bretschneideri ‘Xuehuali’×P. pyrifolia ‘Shinsseiki’) and ‘Hwangkumbae’ pear (P. pyrifolia ‘Niitaka’×P. pyrifolia ‘Nijisseiki’) under normal irrigation and drought stress treatments. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases were used to analyze the differentially expressed genes (DEGs) in two pear genotypes.

Result  There were 4 377 and 3 841 DEGs comparing two pear genotypes under control irrigation and drought stress, respectively. Among these DEGs, 1 340 DEGs were only found under drought stress. There were 1 387, 922 and 1 235 DEGs in three ontologies including biological process, molecular function and cellular component, respectively. There were 349, 139 and 151 DEGs enriched in terms related to drought response of plant including metabolic process, stress response and biomembrane, respectively. The 1 340 DEGs only found under drought stress were matched to 102 KEGG pathways, and three of the pathways were related to phytohormone biosynthesis. Furthermore, among the 1 340 DEGs, 37 genes were annotated as transcription factors which belonged to 17 transcription factor families, and the ethylene responsive factor (ERF) family had 11 DEGs.

Conclusion  In this study, some genes related to endogenous hormone metabolism and transcription factors are found to express differentially in two pear genotypes under drought stress. These genes are probably closely related to the genotypic differences in drought resistance. Our results provide a basis for future study of the molecular mechanism of drought resistance of pear plant.