| That Plant which made use of the " built in " defense system against mechanical wounding and herbivore established a kind of no remain toxin, no pollution could be continuously control agricultural pests' strategies ,which was human being searching for objective continously and patiently. For this great propose, we must study further on the plant built-in mechanisms.Tomato was an important cash crop and a model plant in molecular biology field. Its natural resistance to herbivore attack was because of constitutional or induced phytochemicals taking function.Tomato had been thinking as one of the best model plants in study on the interactions between plants and agricultural pests. Tomato was also a kind of ideal model system for plant induced resistance. In this system, signal pathways that regulated defense responses could be studied.In this research, we follow this kind of basic technical route: tomato protainese inhibitors (Pis) as a molecular marker that could express the strength and weakness of the resistance of tomato to herbivore attack and mechanical wounding for screening the mutant deficient in resistance to insects , cloning corresponding gene based on analysis of the mutant and for further studing the biological function and action in the resistance response.A set of experimental systems had been established in this research on basis of previous study that analysed signaling transduction pathways for plants resistant to insects at molecular lever. The results were as follow:1. That defl and wild type tomato plants were attacked by female adult two spotted spider mite show: defl plant was significantly sensitive to two spotted spider mite, meanwhile the number of eggs per plant on defl in comparasion with that on wile type plant increased distinctly. These results indicated that Defl gene played an important role in reducing the quality of tomato leaves as a food source and oviposition substrate for two spotted spidermite.It had been demonstrated that octadecanoid signaling pathway mediated synthesis of defensive compounds in wild type tomato leaves. Wild type plants subjected to mite feeding accumulated high levels of PI-II and JA relative to untreated control plants. However, PI-II levels in defl plants were only slightly greater than the detection limit of the assay, and JA levels of defl plants were unaffected by herbivory.Two spotted spider mite feeding induced octadecanoid signaling pathway that resulted in activation of PI-II gene and expression of relative genes, further more PI-II protein wereaccumulated. Because Def1 mutation blocked the synthesis pathway of octadecanoid and damaged defensive systems, mutants were attacted seriously.The experiment of exogenous JA inducing resistance showed that JA was required for restoring resistance to insect. Sufficient JA restored defense of the mutant against two spotted spider mite. Wild type plants treated by MeJA reduced the feeding and eggs of two spotted spider mite.It had been demonstrated 35S::prosys constitutively express PI and others defensive genes in the absence of wounding and that 35S::prosys mediated signaling requires octadecanoid biosynthesis and percetion in transgenic experimental with 35S::prosysThrips feeding induced octadecanoid-mediated host responses and constitutive activation of the signal pathway by overexpression of prosystemin that enhanced resistance to multiple cell content feeding herbivores. Those results indicated that systemin was mecessary in systemic resistance of tomato.2. Bulk segregant analysis was used in combination with AFLP to identify markers that were linked to Def1.This experiment showed that W+ plants wre heterozygous for both marker (EM-1 and EM-2), whereas all W" plants were homozygous for the RFLP pattern. The absence of recombinants in the population of 20 BC1 plants demonstrated that EM-1 and EM-2 were linked to the Def1 locus tightly. EM-1 and EM-2 were located on the end of the long arm of chromosome 3. This finding confirms the locations of Def1 on the distal end of chromosome... |
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