Identification and expression analysis of candidate genes related to endodormancy induction and breaking in Pyrus pyrifolia

Abstract

To identify genes related to endodormancy in Pyrus pyrifolia, 124 clones exhibiting differential expression at three stages of bud endodormancy in the Japanese pear (Pyrus pyrifolia Nakai) ‘Gold Nijisseiki’ were isolated using the GeneFishing PCR method. Among the clones, 30, 54, and 19 clones showed high expression during the induction period (IP), deepest period (DP), and breaking period (BP) of endodormancy, respectively. In addition, 21 clones were overexpressed during IP and BP. The basic local alignment search tool searches revealed that 13 of these highly expressed genes have been previously identified. Based on the results of real-time PCR analysis, we focused on 8 genes as potential candidate genes related to bud endodormancy. Expression of 2 genes decreased from IP to DP during endodormancy in ‘Gold Nijisseiki,’ but increased in ‘Hengshanli,’ a plant that enters endodormancy at a different period. These genes were highly homologous to those encoding auxin-responsive family protein and E3 ubiquitin ligase PUB14. Expression of tonoplast intrinsic protein 1 increased briefly before BP as well as after 24h of hydrogen cyanamide (HC) treatment. During BP, genes highly homologous to those encoding thaumatin-like protein and auxin influx carrier component exhibited decreased and increased expression, respectively. This was also observed following HC treatment. Genes identified in this study may play a role in regulating the induction or breaking of endodormancy in the vegetative buds of P. pyrifolia.