Objective  Hexose transporter (HXT) is a kind of monosaccharide transporter, which can transport mannose, fructose, glucose and other hexose substances across the membrane, and participate in the development of pollen and the growth of the whole plant, and then determine the internal quality of fruit. Bioinformatics and expression characteristics of HXT gene in pitaya were analyzed in order to provide a theoretical basis for regulating the fruit quality of pitaya.

Method  A hexose transporter gene was obtained by gene cloning. Bioinformatics analysis was conducted by using NCBI, BioEdit, DNAMAN and other software or databases. The soluble sugar contents were determined by HPLC at fruit maturity stage. The relative expression characteristics of HTX gene in different lines of pitaya and different parts of afruit were analyzed by fluorescence quantitative PCR.

Result  A HXT gene named HuHXTwas cloned from pitaya fruit by PCR amplification. The total length of the gene was 1 230 bp, encoding 410 amino acids. The protein instability coefficient was 35.59, with 32 Ser, 15 Thr and 15 Tyr. There were sucrose, glucose and fructose in pitaya, and glucose and fructose were the main components. The expression of HuHXT was the highest in No. 97 line, followed by Zhanhong No. 2 and No. 128, while No. 15 and No. 16 had the lowest expression level. The expression level of HuHXT was not significantly different in different parts of a fruit. The expression in parts near the pericarp was higher other parts of a fruit.

Conclusion  HuHXT is a member of the Sugar-tr gene family. HuHXT protein is a stable protein with strong hydrophobicity. As a membrane protein, its secondary structure is mainly α-helix and random curl. There is negative correlation between the relative expression of HuHXT and the content of glucose, that is, the higher the HuHXT expression level, the lower the glucose content.