Expression Of A Magnaporthe Griesea Elicitor And Its Biological Function In Activating Rice And Rape Resistance And Growth

Elicitors from diverse plant-pathogen interaction systems were components that induce multiple defense response but have no direct toxicity to plant pests; they have showed good prospects in biocontrol of plant pests. A purified elicitor from Magnaporthe griesea, which have showed good properties of growth promotion and disease resistance, was purified and expressed in E.coli and array of studies were conducted. The results were given below:1. The elicitor protein was purified and isolated from Magnaporthe griesea. The purified elicitor was injected into rabbit to raise polyclone antibody. The elicitor was sequenced by MS-de novo sequence. The elicitor gene was obtained by PCR using M. grieasea cDNA as template, which was given name pemg1 (protein elicitor from M. griesea). The obtained pemg1 was ligated into the EcoR I and Xho I site of pET28a vector. The expressed His₆-PEMG1p takes 7% of total cellular protein. The recombinant elicitor protein was purified by Mag His tag extraction kit, and was exhibited a single band about 42 kD on 12% SDS-PAGE. The expression of pemg1 gene was verified by Western-blotting using the antibody against the natural elicitor.2. Four genes that were responsive to His₆-PEMG1p were up regulated when the rice seedlings were treated by 10ug/ml purified His₆-PEMG1p. The transcriptional activation of a set of defense-related genes was crucial in plant systematic acquired resistance. Those four genes were stkm, fad,pbz1, and pr1. PAL and POD activities were also found to be up regulated by His₆-PEMG1p treatment. By two-dimensional electrophoresis, 14 spots were detected to be up regulated.3. When soaked by 10ug.ml^-1 His₆-PEMG1p, the germination rate of rape seed (Brassica Napus) and root vigor could be significantly enhanced by 10%. Moreover, His₆-PEMG1p could induce rape resistance to Sclerotinia Sclerotiorum in detached leaves. The protein expression profiles in leaves were investigated by two-dimensional electrophoresis. Five increased spots were identified by MAIDI-TOF-MS. Those five proteins were Peroxidase, Rubisco, Myrosinase, Malate dehydrogenase and one unknown protein.Protein elicitor from M. griesea could have the combination of two functions, which confers plants resistance and activates crop growth. This research provided a foundation for further utilizing the protein to promote rice and rape resistance and growth as an elicitor.