Gene expression analysis comparing between dormant and released leaf bud from Japanese pear 'Kosui'

Dormancy of buds is a critical developmental process that allows plants to survive extreme seasonal variations in climate. Dormancy transition in leaf buds of Japanese pear leading cultivar ‘Kosui’ were investigated using 10 K cDNA microarray. Leaf buds collected on October (early endodormancy) and February (breaking stage) were used to monitor the changes in the transcriptome. Over 1000 genes were differentially expressed (p value < 0.05 and 2 fold change) when the early endodormant stage and breaking one were compared to each other. Functional classification revealed that the majority of genes were involved in response to abiotic/biotic stimulus and stress, signal transduction, and transcription. Among them, 76 and 22 genes were significantly (over 10 fold change) highly expressed in early endodormant stage and breaking stage, respectively, this result suggests that even in the endodormant stage, gene expression in the buds is high. Among them, several transcriptional factors were included. The quantitative real-time PCR analysis showed that at least three of their seasonal changes during endodormancy transition phases were similar to two DAM (dormancy-associated MADS box) genes isolated from Japanese pear, suggesting that they might be novel candidate genes associated to dormancy. The gene expression profiles between dormant and released leaf bud were compared.