Development of the New Methods for Ecological Study of Soybean Bacterial Pustule : An Artificial Inoculation Method of Soybean Seed with Xanthomonas campestris pv. glycines for Inducing Disease Expression

Abstract

An attempt was made to develop the artificial inoculation method of seed transmission experiments. Injection of Xanthomonas campestris pv. glycines through seed mycopyle at 10³ and 10⁵ cfu/seed gave 100% seed transmission with no effect on seed germination. When seeds derived from artificially inoculated soybean plants were used, the rate of seed transmission was dependent on the disease severity of parent plants. Seed transmission ratio was higher with seeds taken from plants inoculated 3 times than those inoculated 2 and 1 times respectively. The administration of the vacuum pump (20 lb/inch²) for 10, 20 and 30 min after soaking seeds in bacterial suspenssion at 10⁶ cfu/ml revealed no difference in percent seed transmission. Furthermore, this method significantly reduced seed germination.