Abstract:

The tissue-specific expressed genes of Pyrus betulaefolia in root，stem and leaf were analyzed by RNA-Seq to investigate the molecular mechanism of different growth and development，tissue-specific function in Pyrus plants. With RNA-Seq analysis，19 443，19 567 and 17 876 genes expressed respectively in root，stem，and leaf，were obtained. These genes were classified into 110，110 and 110 categories by GO annotation，and involved in 56，55 and 65 metabolism pathways respectively，by KEGG analysis，including energy metabolism，material transportation，hormone regulation and signal transduction. All of 1 245，971 and 846 differently expressed genes（DEGs）were found respectively in root，stem and leaf，which were involved in 8，8 and 11 significantly enriched pathways，including the metabolism of linolenic acid，fatty acid，sucrose and secondary metabolites，redox reactions and hormone signal transduction. There were 10，6 and 20 of specifically expressed genes related to hormone signal transduction in root，stem，and leaf，respectively. Fifteen genes encoding SAUR protein were specifically expressed in the leaves with a higher expression level in tender leaves and a lower expression level in older leaves. A total of 1 353，1 150 and 1 232 transcription factors were identified in root，stem and leaf，respectively，of which WRKY，MYB and AP2-EREBP had most specifically expressed family members in root. To confirm the reliability of the RNA-Seq data，8 DEGs were selected for qRT-PCR analysis. The results of qRT-PCR were consistent with those of RNA-Seq. Conclusively，specifical expressed genes play a crucial role in tissue-specific function of plants.

Key words: Pyrus betulaefolia, hormone, small auxin-up RNA（SAUR）, RNA-sequencing