Analysis On The Functional Domains Of Protein Elicitor PevD1from Verticillium Dahliae That Induce Hypersensitive Response And Disease Resistance In Tobacco

Verticillium wilt which caused by Verticillium pathogens is a worldwide disastrous plant vascular disease infecting the quality and yield of many important crops, and there is no effective technology to control it now. Protein elicitors from microbe can induce plant resistance by activating pant immune mechanisms and have become a hot research field for plant disease biological control recent years.PevD1(Protein elicitor from vertcillium dahliae) is a protein elicitor isolated from the culture filtrate of cotton Verticillium wilt pathogenic fungus. This elicitor can stimulate hypersensitive response (HR) and systemic acquired resistance (SAR) in tobacco, but the amino acid sequence of PevD1does not share significance homology with other known proteins, and its functional mechanisms still need to be studied in depth. In order to clarify the immune resistance mechanisms induced by PevD1and find the putative functional domains may exist in the sequence, we created specific fragments of PevD1by PCR based on its secondary structure. Recombinant proteins were purified and bioassayed to analyze their functional difference in the stimulation of HR and SAR in tobacco.The research results showed that there are many a-helix,(3-strand and random coil in the PevD1secondary structure. Among them, there are80amino acid residues in the random coil, account for51.61%of the total amino acid residues; the number of amino acid residues of β-strand and α-helix were43and32, and account for27.74%and20.65%of the total amino acid residues, respectively. The PevD1△N98could induce macro-HR, micro-HR and reactive oxygen species (ROS)in the tobacco leaves, and specifically induce the expression of HSR203and HIN1, indicated that the C-terminal57amino acid residues fragment of PevD1may act to elicit HR in tobacco. In contrast, fragment PevD1△C57, the N-terminal of98amino acids of PevD1, did not cause HR in tobacco. However, only fragment PevD1△C57retained the ability to induce SAR against tobacco mosaic virus in tobacco, suggesting that the induction of HR is not essential for SAR mediated by PevD1. This research will provide theory foundations for understanding the relationship between structure and function of PevD1and creation of new microbe protein pesticide.