Study On Evaluation And Mechanism Of Tomato Rootstocks For Resistance To Meloidogyne Incognita

Tomato (Lycopersicon esculentum Mill.) is one of the vegetables cultivation area inChina, because of the higher multiple cropping index and the more common continuouscropping cultivation, resulting in the higher incidence of tomato root-knot nematode disease.In the production practice, it will become the most potential effective method for preventingand control the crop root-knot nematode disease by taking advantage of the resistant varietiesand grafting cultivation of the resistant rootstocks. So, identification and screening of the highresistance tomato rootstocks to Meoidogyne incognita, and determine its resistancemechanism had important theoretical significance and application value. Therefore, theresearch was on the base of screening and evaluation of tomato rootstocks to M. incognitaresistance level, systematically studied related physiological mechanism and specific proteinexpression differences on different resistant tomato rootstocks seedlings. In order to reveal thephysiological mechanisms to tomato rootstocks resistance to M. incognita, and it providedtheoretical basis for breeding highly resistant to M. incognita of tomato rootstocks. The mainresults were as bellow:1. The relative growth rate and relevant disease resistant index of16tomato rootstockseedlings inoculated with M. incognita were measured after50days. The results showed thatthe different relative growth rate of different organs, different disease resistant indexes of16tomato rootstock seedlings and their different coefficient variances resulted from the infectionof M. incognita were different, in which the coefficient variances of relative root fresh massof five relative growth rate was highest20.20%, but that of relative stem diameter was only6.22%. There were also significant differences about gall index (GI), egg granule index (EI),reprodutive frequency (RF) and disease index (DI) of different tomato rootstock seedlings,and the changes were also inconsistent, which indicated that the results about using of singleindicator to classfiy for seedling resistance would be some differences.2. The result of cluster analysis with multiple indexes total indexes was more accuratethan other single index for the resistant class of tomato rootstocks to M. incognita. According to multiple indexes to operate by membership function, we can sure the order of the testedtomato rootstocks resistance to M. incognita. Thereby we established the identification andevaluation method to tomato rootstocks resistant to M. incognita of the combinationsystematic cluster analysis and membership function operation. By the method of clusteringanalysis and subordinate function, we sure Baliya was immune material; BESUPA, BanzhenNo.2, Rootstock606, Rootstock002, Rootstock001, TMS-150, SUPPORT, MIKADO,Rootstock401were resistant materials; ATM052was disease tolerant material; BanzhenNo.1, Beijing No.1were sensitive materials;128, BF xingjin101, Ls-89were highly sensitivematerials.3. Differences in reactive oxygen metabolism before and after inoculating with M.incognita of highly susceptible species Ls-89and highly resistant species Banzhen No.2werestudied. The results showed that, reactive oxygen species generation rate and related enzymeactivities in the roots and leaves of tomato rootstock seedlings, not inoculated with M.incognita, did not show significant differences because of different resistant varieties. Afterinoculating, O2·-generation rate and H2O2content in roots and leaves of two rootstokseedlings had showed a cyclical rise, and Banzhen No.2was significantly higher than Ls-89,however, MDA content in Ls-89was significantly higher than Banzhen No.2. It was showedthat lipid antioxidant ability of resistant rootstok seedlings was stronger. SOD activities werelower in roots and leaves of two varieties seedlings in the early stage of infection, and a largerdecline in Banzhen No.2. But POD and CAT activities changed little in the early stage, to themiddle and late stage significantly increased, which indicated that SOD activities of tomatorootstock seedlings were more sensitive to the infection by M. incognita.4. Phenylpropanes metabolism activities of different resistant tomato rootstock seedlingswere significantly different. The related enzyme activities and phenolics contents ofphenylpropanes metabolism in the roots and leaves of highly resistant species Banzhen No.2seedlings, not inoculated with M. incognita, showed significantly higher than highlysusceptible species Ls-89. After inoculating, the variation of PAL, TAL, PPO activities andtotal phenolis contents, flavonoid in roots and leaves of two rootstok seedlings werebasically the same, and showed a cyclical rise, and Banzhen No.2was significantly higherthan Ls-89, but, the lignin content in roots and leaves increased gradually, and Banzhen No.2 was significantly higher than Ls-89on accumulation and increasing.5. M. incognita infection was significantly influence on root activity and leaf pigmentcontents to Ls-89, but little effect on Banzhen No.2. The soluble sugar, soluble protein,proline, cell wall hydroxyproline contents and chitinase, β-1,3-glucanase activities in the rootsand leaves of tomato rootstock seedlings, not inoculated with M. incognita, did not showsignificant differences because of different resistant varieties. After inoculating, the variationof the related substances contents and enzyme activities were basically the same, showed acyclical rise, and Banzhen No.2was significantly higher than Ls-89.6. The effect of the root exudates of different resistant tomato rootstock seedlings on egghatch was different, and the effect of the root exudates of different periods of the same specieson egg hatch was different, too. Not inoculated with M. incognita, the root exudates of Ls-89stimulated the egg hatch, but Banzhen No.2and Baliya significantly inhibited egg hatch. Afterinoculating, the root exudates of Ls-89were significantly stimulating the eggs hatch, andwere significantly higher than the control of non-inoculated. After inoculating7days,14daysand35days, the root exudates of Banzhen No.2were signifcantly inhibiting the egg hatch,but the21days and28days inhibitory effects were not significant, which were not significantdifferences to the non-inoculated control. The root exudates of Baliya were significantlyinhibiting the egg hatch, were not significant to the non-inoculated control, too.7. Before and after inoculating with M. incognita21days, through analysis the rootexudates compositon of highly susceptible rootstock Ls-89, highly resistant rootstockBanzhen No.2and immune rootstock Baliya seedlings, they were showed that root exudatescompositon of different resistant varieties were different, the same species root exudatescompositon before and after inoculating with M. incognita were different, too. Afterinoculating with M. incognita21days, the substances may play a role for M. incognitainfection in different resistant tomato rootstock seedlings root exudates which were initiallyidentified by comparing analysis. They were1,2-benzenedicarboxylic acid, diisooctyl ester,2,2′-methylenebis[6-(1,1-dimethylethyl)-4-methylphenol,1,2-benzenedicarboxylic acid,dibutyl ester, L-(+)-ascorbic acid2,6-dihexadecanoate,2-benzothiazolinone, N′-cyclooctyl-N,N-dimethyl-urea, Phthalic acid,6-ethyloct-3-yl2-ethylhexyl ester, Cyclohexyl isothiocya-nate,8-octadecenoic acid, methyl ester,(Z)-9-octadecenal,3,7-dimethyl-2,6-octadienal, cis- 9,10-epoxyoctadecanoic acid,9,10-dihydroxyoctadecanoic acid, Ambrettolid, Octadecanoicacid,2-(2-hydroxyethoxy)ethyl ester, Phosphoric acid, tris(2-ethylhexyl) ester.8. M. incognita development process in different resistant tomato rootstock seedlingroots and the number of eggs and juveniles within rhizosphere matrix were found that showedthe number of juveniles in roots of Ls-89and Banzhen No.2had increased, and Ls-89weresignificantly higher than Banzhen No.2, though, juveniles were not exist in Baliya. Thejuveniles penetrated into Banzhen No.2roots not only later than Ls-89, but also the numbersignificantly lower; and only a few developed into the third instar larvae and fourth instarlarvae, the number were significantly lower than Ls-89. Because of second infection, thenumber of juveniles in Ls-89and Banzhen No.2within rhizosphere matrix increased, andthey were significantly higher in Ls-89than in Banzhen No.2, but continued to decline inBaliya. The number of eggs within rhizosphere matrix changed acutely, late in infection, theywere significantly higher in Ls-89than in Banzhen No.2, but they were non eggs in Baliya.9. Total proteins were identification and analysis from leaves in the highly susceptiblerootstock Ls-89, the highly resistant rootstock Banzhen No.2and the immune rootstockBaliya after inoculating with M. incognita.682protein spots were detected, of which32protein spots were differentially expressed significantly, through mass spectrometry andNCBI database search, only17protein spots were obtained. They were peroxidase precursor,glutathione S1-transferase, class-phi, ATP synthase CF1alpha subunit, vacuolar H+-ATPase A1subunit isoform, ATP synthase beta chain, chlorophyll a/b binding protein, photosystem Ilight-harvesting chlorophyll a/b-binding protein, ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit,50S ribosomal protein L12, chloroplastic, heat shock70protein,HSP68=68kda heat-stress DnaK homolog, Threonine deaminase, leucine aminopeptidase,hypothetical protein SynRCC307-1195.