Cloning and expression analysis of ASR genes in pepper (Capsicum annuum L.)

【Objective】 ASR(ABA-stress-ripening) genes were cloned in this study. By bioinformatics analysis and expression analysis under different tissues and abiotic stress treatments, to provide a reference for further study on the mechanism of ASR gene family in pepper fruit development and abiotic stress.【Method】 ASR genes were cloned from Zunla-1 cultivar. A series of bioinformatics and phylogenetic analysis were carried out to evaluate the family members. The tissue specific expression patterns and the expression patterns under ABA, high temperature, high salt, and drought stress were detected by real-time fluorescence quantitative PCR.【Result】 Two ASR genes were cloned, named as CaASR2 and CaASR3. The full lengths of CaASR2 and CaASR3 were 987 and 938 bp, and the open reading frame(ORF) were 333 and 339 bp in length, which encoded 110 and 112 amino acids, respectively. Their molecular weights were 12.45 and 12.73 kD, and their theoretical isoelectric points(pI) were 7.47 and 6.50, respectively, and they were hydrophilic protein. The results showed that CaASRs were predicted to be in the nucleus and contained ABA/WDS(ABA/water deficit stress) domain. All CaASRs genes contained two exons and one intron, and the promoter region contained ABA response element ABRE. The amino acid sequences of CaASR1, CaASR2 and CaASR3 were highly similar to those of ASR protein amino acid NP_001269248.1(80.20%), NP_001307920.1(91.30%) and NP_001234137.1(96.43%) in tomato(Solanum lycopersicum), which indicated the relative conservation of evolution. The results of tissue specific expression analysis showed that they were expressed the lowest in flower, and the moderate in root, stem, leaf, and seed, gradually increased with fruit grew, and especially highly expressed in color-changing fruit and mature fruit. The expression levels were significantly increased under ABA stress, high temperature, high salt and drought(P<0.05), and CaASR3 had the fastest response, whose up regulated expression levels were higher than that of other homologous genes.【Conclusion】 Three ASR genes in pepper genome have typical characteristics of the ASR family and play important roles in different tissue and abiotic stress resistance in pepper.