Comparative Analysis of Transcriptomes to Identify Genes during Bud Dormancy of Pyrus pyrifolia ‘Huanghua’

The study of pear dormancy mechanisms is currently a major research area in pear production and has high economic significance for agricultural production. We selected the southern sand pear cultivar Pyrus pyrifolia ‘Huanghua’ as the test material to study the pear dormancy process through microscopic observation of pear flower buds. The endodormancy period is abbreviated as D_bud. Similarly, the endodormancy release initiation period and the ecodormancy period are referred to as DB_bud and G_bud, respectively. Meanwhile, RNA sequencing was used to obtain the gene expression profile of Pyrus pyrifolia ‘Huanghua’ flower buds. The RNA sequencing results indicated that there were 224 differentially expressed genes (DEGs) in endodormancy (D) vs. endodormancy release initiation period (DB), while 975 were identified between endodormancy and ecodormancy (G). Finally, a total of 868 DEGs were found in the DB vs. G comparison. The expression levels of the genes Pbr009498.1 (LAX1-1), Pbr012348.1 (LAX1-2), Pbr021158.1 (GH35), and Pbr031621.1 (LAX2) encoding IAA were significantly higher during the DB_bud than during the D_bud. The expression level of Pbr025864.2 (IAA13) during the D_bud was significantly higher than the DB_bud and G_bud. The Pbr041942.1 (GID1B) gene also showed a significant increase during ecodormancy. Taken together, these results suggest that these genes, annotated as LAX1, GH35, LAX2, IAA13, and GID1C, are involved in endodormancy maintenance and in the transition from endodormancy to ecodormancy in Pyrus pyrifolia ‘Huanghua’.