Cloning And Preliminary Functional Analysis Of CaPT11 And CaHIR4 Genes Related To Phytophthora Capsici Resistance In Pepper(capsicum Annuum L.)

Pepper(Capsicum annuum L.) is an important vegetable crop which is widely cultivated in the world. But the production of pepper is seriously damaged by Phytophthora capsici. Compared with other prevention mesure, disease resistance breeding by molecular technique is an efficient approach to solve this problem. So the screening and functional analysis of disease related genes have a great significance to reveal the interaction mechanism between pepper and P. capsici. In this study, we isolated two differential expression genes CaPTI1 and CaHIR4, which are screened from the transcriptome database, and then analyzed the function of these genes. The main results are as follow:1. The CaPTI1 and CaHIR4 genes were isolated firstly. CaPTI1(GenBank No. KJ690096) gene contained a single AP2 domain, was belong to ERF subfamily. It included an open reading frame(ORF) of 543 bp, which was predicted to encode a protein of 180 amino acids. The theoretical molecular mass of the encoded protein was 20.3 kDa, with the calculated pI of 8.46. CaHIR4(GenBank No. KJ690097) contained a SPFH domain, which belonged to hypersensitive induced reaction(HIR) protein family. The ORF of CaHIR4 was 873 bp which encoding a protein of 290 amino acids, the predicted molecular mass was 32.3KDa and the calculated pI was 5.05.2. The character of tissue expression of CaPTI1 and CaHIR4 Gene in Pepper Plants was analysised. The results showed that the highest expression of CaPTI1 was detected in root(26 fold of that in leaf), then was stem and flower(3.51 and 2.45 fold of that in leaf respectively), but few expression was detected in fruits. Whatever the highest expression of CaHIR4 was detected in fruits(2.98 fold of that in root), then was the flower, the expression level in root and stem was almost the same with that in leaf.3. The expression patterns of CaPTI1 and CaHIR4 genes under biotic and abiotic stresses was analyzed. The results showed that the expression of CaPTI1 and CaHIR4 gene in root and leaf could be induced by the inoculation of compatible P. capsici. The expression of CaPTI1 gene was up regulated in all abiotic stresses(include ethephon, salicylic acid, methyl jasmonate, H2O2, drought and chilling stresses), and increased intensely especially in the hormone treaments. While the CaHIR4 gene showed a down regulated expression pattern in hormone treaments and chiling stress, and slightly up regulated expression pattern in H2O2 treament and drought stress.4. The function of CaPTI1 gene was preliminary identified by the technology of VIGS. And the result showed that the silence of CaPTI1 gene in pepper plant could not only reduced the expression of defence related genes CaPR1, CaDEF1 and CaSAR82, but also the root activity, which were resulted to the weakness of plant resistance to P. capsici.5. Promoters of CaPTI1 and CaHIR4 genes were cloned, analysis of cis-elements in promoter showed both of them contain the basic elements of promoter. Histochemical stain after transient expression in tobaco leaves confirmed the activity of these promoters.