CHARACTERIZATION OF INDIANA HETERODERA GLYCINES VIRULENCE PHENOTYPES AND STUDY RESPONSE OF MELOIDOGYNE JAVANICA TO TOMATO ROOT EXUDATES

  Heterodera glycines or soybean cyst nematode (SCN) is one of the most yield-limiting soybean plant pathogens. The HG (Heterodera glycines) type test is a greenhouse test to determine the virulence of SCN populations to seven soybean “indicator” lines. Since there has not been a survey of SCN virulence phenotypes in Indiana in over a decade, a total of 124 samples were collected, and all tested positive for SCN. Of 42 selected populations for the HG type test, 88% were virulent to the soybean breeding line PI 88788, from which most SCN-resistant cultivars derive their resistance. All populations were virulent to at least one indicator line, including PI 548402 (‘Peking’), which pose problems for the future of soybean breeding for SCN. Meloidogyne spp. or root-knot nematodes (RKNs) are extremely damaging to agriculture, especially to specialty crops. RKN species are attracted by plant root exudates. The gene expression of M. javanica second-stage juveniles was determined after exposure to tomato root exudates, and the differentially expressed genes were analyzed.