Abstract：Columnar trait of apple (Malus × domestica Borkh.) is controlled by a single dominant Columnar (Co) gene, located in apple genome chromosome 10. Many putative genes are predicted in the Co region. Screening genes related to the columnar trait in apple provides theoretical basis for identification of the Co gene. Sixty-four putative genes in the Co region (18.51~19.1 Mb) were screened by SRA/EST (Sequence Read Archive/Expressed Sequence Tags) database. Samples of shoot tips, leaves and buds from columnar cultivar ‘Wijcik’ and non-columnar cultivar ‘McIntosh’ were used to extract total RNA, respectively, and the cDNA mixture of an equal volume of each sample after reverse transcription, was used as materials to conduct. Reverse transcription PCR (RT- PCR) was to amplify partial cDNA sequences of putative gene. Quantitative Real-time PCR (qRT-PCR) reactions were performed to analyze the differential expression of putative genes in apple shoot tips. 32 putative genes expressed in different apple tissues or organs were detected by searching SRA/EST database. 29 putative genes were obtained by RT-PCR amplification, and 15 genes were with significant differences in apical tips of the columnar apple by qRT-PCR analysis. Among them, 6 genes (No.26, No.41, No.33, No.38, No28 and No.32) were up-regulated significantly (P＜0.05), and 9 genes (No.30, No.9, No.37, No.6, No.44, No.10, No.27, No.11 and No.4) were down-regulated significantly in apical tips of the columnar cultivar(P＜0.05). In this study, 15 genes with significant differences in the apical tips of the columnar apple could be regarded as candidate genes of the Co. The candidate genes are identified to elucidate the function of critical genes and molecular mechanisms of the apple columnar mutation in the Co gene region, and serve as a directional genetic improvement for apple trees.
