Abstract:

The aims of this study are to identify WRKY transcription factors in the whole genome of pepper, select the CaWRKYs induced by Phytophthora capsici and analyze the signal pathways involved in the key CaWRKY genes. CM334 and NMCA10399 were used as experimental materials. Based on genome and RNA-seq data, gene expressions were obtained by qRT-PCR under the treatment of salicylic acid (SA) and methyl jasmonate (MeJA). The results showed that 69 CaWRKYs were identified in the whole genome of pepper. At the time point of 12 hpi, there were 7 and 3 CaWRKYs significantly and differentially expressed in resistant and susceptible materials, respectively. At 36 hpi, 13 and 22 genes were significantly and differentially expressed in resistant and susceptible materials, respectively. These results indicated that resistant material could respond more quickly to the pathogens. Among the 8 key CaWRKYs selected, CaWRKY19 and CaWRKY65 were induced by SA and up-regulated expressed, while CaWRKY50 was induced by MeJA and up-regulated expressed. CaWRKY25 was up-regulated by SA and down-regulated by MeJA, while CaWRKY49 was down-regulated by both SA and MeJA. Signal pathway analysis speculated that CaWRKY19 and CaWRKY65 were involved in pepper defense against Phytophthora through SA signal pathway, CaWRKY50 through JA signal pathway, while CaWRKY25 and CaWRKY49 through both SA and JA signal pathway.

Key words: pepper, Phytophthora blight, WRKY transcription factor, induce, signal pathway