Identification Of Pathogen Of Soybean Bursa And Its Pathogenicity

Soybean cyst nematode(SCN) disease is one of the most dangerous soybean diseases in the world. Accurate identification of physiological race and pathogenicity of SCN is greatly significant for SCN disease control and breeding for disease resistance. Infection of SCN is affected by root exudates of hosts. Study on chemotaxis of SCN to acetic acid and sodium chloride benefits to understanding mechanism of infective juvenile searching hosts, which possesses important theoretical significance on SCN disease control.Cyst index was used to identify physiological races collected from Taian Shandong, Anda 1 and Anda 2 sites. SCN was purified by single cyst reproduction before identification. Results showed that SCN from the three sites was physiological race 4. Egg index identification showed that SCN from Taian Shandong, Anda 1 and Anda 2 were physiological race 4, 14 and 4, respectively. Physiological race identification of cyst index and egg index was different. Egg index can provide more accurate evaluation for physiological race identification.Pot experiment was used to test disease resistance of eighteen soybean varieties of Heilongjiang province to different SCN from the three sites and pathogenicity of SCN. None soybean resistant variety was found by cyst index identification. Soybean varieties of SCN resistance 2 and 09-138 had high resistance to physiological race 4 of Anda 1 based on egg index identification, and the varieties of SCN resistance 2, 7, 8 and 13 had high resistance to physiological race 4 of Anda 2. Pathogenicity of physiological race 4 of Taian Shandong was stronger than that of physiological race 4 of Anda 2 based on evaluation of cyst and egg indices.Pluronic F-127 gel was used to test chemotaxis of SCN to acetic acid and sodium chloride. Results showed that SCN had taxis to acetic acid and sodium chloride, but the taxis was affected by concentration of acetic acid and sodium chloride. SCN was distinctly attracted to acetic acid with 850mM/mL and sodium chloride with 50mM/mL.