A Reassessment of Virulence Phenotypes of Soybean Cyst Nematode (Heterodera glycines) in China with HG Typing Method.

ABSTRACT

Soybean cyst nematode, Heterodera glycines Ichinohe, is the most destructive pest of soybean (Glycine max) worldwide, including China. H. glycines virulence phenotypes can be described in two ways. One is the race determination test that uses four soybean lines to categorize H. glycines into 16 "races" (3). The HG type designation is similar, but avoids the implications of the term "race" and includes seven soybean lines rather than four (2). In China, previous data revealed the occurrence of nine H. glycines races including races 1 through 7, 9, and 14, whereas HG types have not been recorded (1). The objective of this study was to reassess virulence phenotypes of H. glycines in China by means of HG types. In 2011 and 2012, 10 SCN populations from the primary soybean production regions of China were identified as six races (races 1, 2, 3, 4, 5, 6, and 14) with the race test scheme (3) and were cultured on a H. glycines-susceptible soybean cultivar. In 2013, seven indicator soybean lines (PI 548402, PI 88788, PI 90763, PI 437654, PI 209332, PI 89772, and PI 548316) plus the susceptible standard soybean "Lee74" were used to determine the HG types of these populations following standardized procedures (2) with some modification in a growth chamber set at 28°C under 16-h days. After 30 days, females were extracted from roots and collected, and a female index was calculated for each indicator line (2,3). The average number of females on Lee74 was more than 100 in all the tests. Eight HG types were identified in the populations tested HG type 0 (race 3), HG type 7 (race 3 or 6), HG type 2.7 (race 1 or 5), HG type 5.7 (race 3), HG type 1.3.7 (race 14), HG type 2.5.7 (race 1), HG type 1.2.5.7 (race 2), and HG type 1.2.3.5.7 (race 4). To our knowledge, this is the first report of H. glycines HG types in China, which will contribute to development of management strategies implementing the use of resistant cultivars. This work was supported by the Special Fund for Agro-scientific Research in the Public Interest 200903040-03 and the China Agriculture Research System CARS-04. References (1) W. G. Lu et al. Agr. Sci. China 5615, 2006. (2) T. L. Niblack et al. J. Nematol. 34279, 2002. (3) R. D. Riggs and D. P. Schmitt. J. Nematol. 20392, 1988.