Preliminary Study Of Co-infection Of Meloidogyne Spp.to Tomato And Resistance Identification Of Tomato Varieties Against M.Incognita

Root-knot nematodes(Meloidogyne spp.,RKN)are important parasites of thousands of plants and damage seriously many agricultural crops.They are the mainly causal agents for soil-borne diseases in greenhouse crops of China.The species of M.incognita,M.javanica and M.arenaria are the dominant RKN species in southern part of China.Understanding the competition rules of RKN species in co-infection to plants and identifying the resistance of crop varieties against RKN is critical important for making integrated strategies for disease control.The combined inoculations of second stage juveniles(J2)from Meloidogyne incognita,M.javanica and M.arenaria were carried out on tomato seedlings.The results showed that the numbers of females produced by M.javanica were larger than that by M.arenaria and M.incognita,which demonstrated the strong competition of infection in their co-infections to tomato seedlings.The infection ability of M.arenaria was higher than that of M.incognita in their co-infeciton.The attraction of J2 of three Meloidogyne species to tomato root tips was tested using Pluronic F-127 gel as a medium.The results showed that J2 of three species were attracted to the root tips during 2-6 h and J2 invaded into roots after 6 h.The J2 number of M.javanica aggregated around root tips was larger than those of M.incognita and M.arenaria,showing the significant differences(P<0.05).M.javanica was demonstrated to be more attractive to tomato.The resistance against Meloidogyne incognita by seventeen tomato varieties was detected by the artificial inoculation of second-stage juveniles and the cleaved amplified polymorphic sequences(CAPS).The results from inoculation tests showed that variety of Zhanxian,Shuangkang No.26 and Shuangkang No.228 were highly resistant to M.incognita,variety of Xianchongjue No.3,Xianchongjue No.1,Shuangkang No.22,Shuangkang No.40,Shuangkang No.39,ShuangkangNo.38,Quanneng No.216 and Ouguan were resistant.The rest varieties were susceptible.The CAPS detected only Shuangkang No.228 and Shuangkang No.38 carried homozygous Mi gene and the others were free of homozygous Mi gene.