Objective   Bioinformatics and expression of trehalose-6-phosphate synthase (TPS) gene in chili peppers,CaTPS9, were studied to understand its role in response to abiotic stress during the plant growth.

  Method  CaTPS9 was cloned from Qiangfeng 101 to analyze the physicochemical properties, protein structure, cis-regulatory element, and phylogenetic tree. Expressions of the gene in the pericarp and placenta of a commercial pepper as well as the young pericarp, ripened pericarp, young placenta, ripened placenta, leaves, roots, stems, and flowers of chili pepper plants under varied stresses including low temperature, 3-indoleacetic acid(IAA), abscisic acid(ABA), salicylic acid(SA), gibberellin A₃(GA₃), and methyl jasmonate(MeJA) were determined using qRT PCR.

  Result  The full-length cDNA sequence of CaTPS9 was 2604 bp encoded 867 amino acids. Located in the cytoplasm, the protein contained two conserved domains, Glyco_transf_20 and Trehalose_PPase, with a molecular weight of 97.60 kDa, an instability index of 44.27, and a theoretical isoelectric point of 5.63. It was a hydrophilic protein free of transmembrane structure and signal peptide sequence with a structure consisting mainly of alpha helixes and random coils. Phylogenetically, CaTPS9 was close to the homologous genes in Nicotiana tabacum, Solanum lycopersicum and Solanum tuberosum. It had hormones response, stress response, and plant growth and development cis−elements and was expressed most highly in the leaves, lowly in the placentas of a commercially available pepper, and significantly by 12 h SA induction. Stress, such as low temperature, IAA, ABA, GA₃, and MeJA, significantly inhibited the expression.

  Conclusion   It appeared that CaTPS9 might regulate the response of chili pepper plants to various abiotic stresses through the trehalose biosynthetic pathway.