Study On Polymorphism Of Meloidogyne Incognita Populations

Root-knot nematodes of genus Meloidogyne are the major agricultural pest in the world of a widerange of crops, which lead to economic loss every year. It is the most efficient path for nematodecontrol. However, virulent populations completely overcoming the resistance gene still occur afterwidely cultivating the resistance variety. It means that widely variation and high polymorphism exist inroot-knot nematode populations. Knowledge of polymorphism of root knot nematodes plays animportant role in rational distribution of resistance genes, breeding for disease resistance anddevelopment of more prevention strategies. Microsatellite is one of the most effective means ofpolymorphic research. Here, we studied on microsatellite polymorphism in Meloidogyne incognita.Polymorphic microsatellite makers and specific molecular makers correlated with virulent nematodepopulation were developed. Meantime, we gave insight into biological control for root-knot nematode.The main contents are summarized as following:Microsatellite loci were screened from M. incognita genome date, with the motif criteria that di-,tri-, tetra-, penta-and hexa-nucleotide microsatellites repeat at least8,5,5,5and5times, respectively.Finally，1620microsatellite primer pairs were got for polymorphism analysis.63M. incognita individuals are from7provinces of China as the materials, a whole genomeamplification step was employed. Then we analyzed the polymorphism of100microsatellite loci fromthe1620microsatellite loci. Finally9microsatellite loci were found polymorphic, of which allelesranged from3to24and8alleles on average, with high polymorphism in3geogrophical population.These makers could be used for analysis of polymorphism and genetic structure of M. incognita.Root-knot nematode populations include avirulent and virulent population overcoming resistantgenes Me3as the experiment materials, polymerase chain reaction was done with100primer pairsdesigned according to M. incognita genome and19pairs reported in literature to screen specific bandamong three populations. And subsequently SCAR primers were designed and a multiplex PCR reactionsystem was built.7primer pairs amplifying stable bands were screened,2of which were converted intoSCAR makers. Multiplex PCR from avirulent population and Me3-virulent isolates generated afragment of999bp and629bp respectively, while from the mixed group generated both of the abovefragments. Virulent mutation makers were successfully developed in M.incognita, and one-stepmultiplex PCR can be used for identification of Me-virulence.