| Root exudates play important roles in the infection of Meloidogyne incognita.A great deal of documents have elucidated that the content of root exudates had been changed and these transformations would directly affect on M.incognita when plants grow in varied seasons or habitats,confirming root exudates would attract M.incognita as signal factors.However,the defined metabolites and how these involved in M.incognita interaction have not been clear.The present work was conducted to detect root exudates of six tomato cultivars for chemotaxis to M.incognita.Furthermore,volatile substances from root exudates of six tomato varieties were determined and some pure volatiles were selected for verification.Conclusions are as follows:1.Chemotaxis of root exudates from susceptible tomato Jiabao to M.incognita were examined.The results showed that chemotaxis index of n-hexane crude extracts(9.5×10-4 ppm and 9.5 ×10-5 ppm)to M.incognita had good efficacy,reaching to 0.30 and 0.26,respectively.Raffinate phase crude extracts were proved to be attractive to M.incognita at different concentrations and chemotaxis index were above 0.20,the highest was 0.28 at the concentration of 1.0×10-3 ppm.Moreover,raffinate phase crude extracts were used for more detection,with the ratio of 95%water and 5%methanol,chemotaxis index were greater than 0.25,showing obvious chemotaxis to M.incognita at a variety of concentrations and it peaked(0.38)when the concentration came to 1×10-4 ppm.2.The volatile compounds of n-hexane crude extracts for hydroponic culture of six tomato varieties was detected by GC-MS.A total of 204 volatile compounds were tested.Then,11 pure volatiles in all volatile compounds of n-hexane crude extracts from tomato Jiabao were choosed for chemotaxis examination.The results indicated that M.incognita would be attracted apparently by Erucic acid(lppm),1-Dodecanol,2-octyl-(7.5 × 103 ppm),1-Octadecene(7×108 ppm)and 1-Decanol,2-hexyl(8×108ppm),the chemotaxis index were 0.32,0.34,0.28 and 0.28,respectively.3.Root exudates of six tomato cultivars for chemotaxis to M.incognita was detected,n-hexane crude extracts from tomato Jiabao(9.5×10-4 ppm)had best efficacy,chemotaxis index could be up to 0.30,compared with tomato Zhongza(0.50)at the best concentration of 9.5×10-4 ppm n-hexane crude extracts.N-hexane crude extracts from tomato Gailiangmaofen(9.5×105 ppm)played a good effect on M.incognita,with chemotaxis index being 0.34.Another CMV tomato Benchi was proved effective when the concentration was at 9.5×10-1 ppm,chemotaxis index was the highest,up to 0.31.N-hexane crude extracts from TOMV tomato Jiazhou 406(9.5 ×10-1 ppm)and Wannongfenba(9.5×10-6 ppm)were also found to be attractive to M.incognita,chemotaxis index were 0.33 and 0.23,respectively.Volatile compounds from susceptible tomato Zhongza and Jiabao showed the highest of all,with 93 and 63,respectively.54 compounds were found in CMV tomato Gailiangmaofen and Benchi.In contrast,TOMV tomato Jiazhou and Wannongfenba were the lowest,only 26 and 42.There was at least one compound from forenamed four compounds found among those five tomato varieties.4.M.incognita infects plants with the free second instar larvae(J2),which must parasitic in plants root,and J2 could not be easily obtained.As a consequence,it greatly restricted the progress of research.A bacterial strain of Trichoderma viride was screened to increase the egg hatching of M.incognita in our study.Trichoderma viride 3838 agent,diluted 10 times,with heating 100 ?,can be available for egg masses hatching,increased by more than 200%and were proved high-efficiency and fast,which has potential application in some research of J2.Highlight of this research:1.Chemotaxis of n-hexane and raffinate phase crude extracts for root exudates from tomato Jiabao was proved to be attractive strongly to M.incognita.2.It was confirmed that these tomato cultivars showed obvious chemotaxis to M.incognita at a variety of concentrations,and there was at least one component from forenamed four compounds found all tomato varieties.3.Trichoderma viride 3838 agent could be available for egg masses hatching and were proved high-efficiency and fast. |
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