Study On The Resistance Of Cucumis Metuliferus To Meloidogyne Incognita

With the deepening of the adjustment of agricultural planting structure in recentyears and the rapid development of facility vegetable area, cucumber as one of a largevegetablecrops facility plays an important role in agricultural production. However,most of the facilities are used in the production of crude stage, controlled environmentis still poor. So long-term cropping cultivations are causing various diseases occurringdisaster,especially soil-borne diseases.Such as, root-knot nematode damage isparticularly severe and it often results in severe yield loss. Due to the current lack ofresistant materials against root knot nematode at home and abroad, there are still notcucumber varieties resistant materials to Meloidogyne incognita. Cucumis metuliferus,as wild resistant materials to root-knot nematode, has been payed the most attention toin breeding research. In order to provide certain theoretical basis in cucumberbreeding,the resistance of Cucumis metuliferus materials to Meloidogyne incognitawere stdudied in this paper.The main results are as follows:1. Resistance Identification of Cucumis metuliferus to Meloidogyne incognitaand Characteristic AnalysisThe resistance of Cucumis metuliferus CM3against M. incognita was evaluatedusing artificial inoculation in greenhouse, and the resistance to root-knot nematodesdevelopmental pathology was observed. The results showed that C.metuliferus CM3had a stable resistance to M.incognita.There were some significant differences on thenumbers and size of root knot between C.metuliferus CM3and C.sativus9930. Theobservation of M.incognita developmental stage revealed that the development of J2M. incognita was suppressed in C.metuliferus. M. incognita was able to complete theirlife cycle in C. sativus9930within21d，but could not complete their life cycle in C.metuliferus within28d，and only a small number of nematodes could develop to theadult in42d. The results confirmed the previous reports that the resistant reaction ofCucumis metuliferus against M. incognita was not hypersensitive response.Thenematodes can successfully invade, since feeding sites (giant cells) formation wasblocked and nematode growth and development were inhibited.So their normal life cycle was unable to complete.The resistance identification of C. metuliferus to M.incognita provided a useful basis for cucumber breeding.2．The Genetic Characterization Analysis of the Cucumis metuliferus materials toM. incognitaBased on the results above, the resistances of C.metuliferus ’CM3’(PI202681male),’CM27’(PI482460female), F1-positive, F1-anti, F1, F2, BC1P1and BC1P2were evaluated. The results showed that C.metuliferus ’CM3’ of RKI=1.7, wasresistant, F1-anti RKI=1.96, was resistant, F1-positive RKI=2.23,was mediumresistant, F1’s RKI=2.08, was medium resistant, BC1P1the RKI=2.2, was mediumresistant, BC1P2the RKI=2.77, was medium resistant,’CM27’ of RKI=3.0, wassusceptible. Based on F2populations of the Cucumis metuliferus CM3(resistant) andCM27(susceptible) against M.incognita, the statistical analysis showed that theseparation ratio of resistant lines and susceptible lines was3:1,which is a singledominant gene resistance quality straits.3.Cloning and Expression of Peroxidase gene in Cucumis metuliferusThe POD gene was cloned from Cucumis metuliferus by RT-PCR using primersof homologous sequences. The gene named CM POD and GenBank accession numberwas KJ508398. The size of POD gene was987bp, and encoding328amino acids withmolecular weight of36171Da. In addition, the expression of CM3’ POD genes afterinfection of M. incognita,the samples of Cucumis metuliferus in3d,14d,28d wasresearched by fluorescence quantitative PCR. The results showed that the expressionof CMPOD gene was down-regulated.Though the highest expression in3d afterinoculation and then expression was reduced. PR proteins were found up-regulated inthe detection of resistance,but this resistance response the total POD is not positivelycorrelated with the expression of the plant, but on the contrary, it shows that the rootknot POD genes related to the development, but also further explain the resistance isnot a reaction CM3hypersensitive response, but antibiotic reactions.