Pathotoxin Effects in Sorghum Are Also Produced by Mercuric Chloride Treatment

Pathogenic isolates of Periconia circinata produce a host-specific toxin (PC-toxin) and cause a root and crown rot in susceptible genotypes of sorghum. Treatment with PC-toxin leads to selective development of disease symptoms and an increase in synthesis of a group of acidic, low molecular weight proteins only in susceptible genotypes. Treatment of sorghum seedlings or excised root tips with HgCl 2 resulted in responses indistinguishable from those produced by treatment with PC-toxin, but the effects were not genotype specific.