Abstract:

Abstract: 【Objective】 To provide an insight into mechanism of pepper’s cold resistance and cultivar development,the sequence characteristics of the aquaporin gene CaAQP in pepper were analyzed and the expression profiling of the chilling tolerant Capsicum annuum cv. P70 was studied after treatment at 4℃ cold stress. 【Method】 The rapid-amplification of cDNA ends (RACE) was used to amplify the full-length CaAQP gene, and the bioinformatics software was employed to analyze the structures and function of the coded protein. At the same time, the chilling tolerant pepper P70 treated at 4℃ was used as material and the real time-PCR was adoped to study the expression profile of gene CaAQP, the peper cv. treated at 25℃ was used as control. 【Result】 A gene encoding the aquaporin cDNA (designated as CaAQP, GenBank Accessin No. GU116569) was cloned from leaf of Capsicum annuum cv. P70 by RACE. The full-length CaAQP gene cDNA was 1 032 bp in length, which included a potential open reading frame of 753 bp, a 5′-untranslated region (5′-UTR) of 69 bp and a 3′-untranslated region (3′-UTR) of 210 bp, encoded a protein of 250 amino acids with a predicted molecular mass of 25.7 kD. Bioinformatics analysis demonstrated that CaAQP exhibited a typical structure with six membrane-spanning domains and an internal symmetry showing two highly conserved Asn-Pro-Ala (NPA) motifs, and possessing the MIP family signal consensus sequence. The CaAQP amino acids showed high identity with other 10 plant species TIP subfamily by NCBI homology comparison analysis. Phylogenetic analysis indicated that CaAQP was clustered with the SLAQP from Solanum lycopersicum. Real time-PCR analysis showed that the expression of CaAQP was down-regulated by low temperature stress. 【Conclusion】 An aquaporin gene CaAQP was firstly cloned by cDNA-AFLP and RACE from leaf of Capsicum annuum cv. P70. The CaAQP gene is a member of the MIP protein family, and has the typical function region. The expression profiling of this gene indicates that the CaAQP gene may play an important regulating role during low temperature stress. This study provides important information for the future research on the gene-expression regulation during cold stress.

Key words: pepper, aquaporins, gene cloning, sequence analysis, real time-PCR