【Objective】Capsicum chinense is a member of the Solanaceae family and Capsicum genus, most of which have a rich fruity aroma produced by
【Objective】Capsicum chinense is a member of the Solanaceae family and Capsicum genus, most of which have a rich fruity aroma produced by branched-chain esters. Alcohol dehydrogenase (ADH) is an important enzyme that affects the content of branched-chain esters, catalyzing the reversible transformation between corresponding alcohols and aldehydes. Identifying the members of the ADH gene family in C. chinense, and analyzing their expression patterns in different parts of the plant will provide references for the aroma synthesis mechanism of pepper fruit.【Method】Through bioinformatics analysis, real-time fluorescent quantitative PCR, and gaschromatography-mass spectrometry, the volatile substances and the ADH gene family in C. chinense were identified and analyzed for expression characteristics.【Result】Eight ADH genes were identified from the C. chinense genome, distributed across four chromosomes and named CcADH1-8. The prediction of physicochemical properties showed that lengths of the amino acid sequence encoded by the ADH gene family range from 368 to 457 aa, with molecular weights between 40 to 49 kD, and isoelectric points between 5.50 to 9.12. The hydrophilicity coefficients of CcADH4-6 were positive, while the rest of the gene family members were negative. The instability indices were ranged from 22.23 to 44.81. Protein structure prediction revealed that the secondary structure of CcADH was predominantly composed of α-helices and random coils, while CcADH4 and CcADH6, as well as CcADH7 and CcADH8, were similar in the tertiary structurer. Subcellular localization prediction showed that all CcADHs were localized in the cytoplasm. The prediction results of cis-acting elements in the promoter region showed the promoters of CcADH contained 12 types of cis-regulatory elements. Spatiotemporal expression analysis showed that CcADH6 had no detectable expression in 'JT-1' and '7054' Capsicum plants, CcADH7 was highly expressed in flowers and the 4th stage of fruit development in 'JT-1', and CcADH5 was highly expressed in the 3rd stage of fruit developemnt in '7054'.【Conclusion】The volatile substances in C. chinense fruits are accumulated significantly in the middle and late stages of fruit development, which clarified the expression pattern of ADH gene family in C. chinense, and found that CcADH5 and CcADH7 are respectively consistent with the variation trends of branched-chain esters in the fruits of '7054' and 'JT-1', The reactions they participate in provide specific substrates for the downstream AAT, influencing the content of branched-chain esters in the fruit.
