The elicitor components in culture liquid of Phytophthora boehmeriae

The cultured filtrate of Phytophthora boehmeriae was saturated by(NH 4) 2 SO 4,ultrafiltrating the culture filtrate with 30× 10 3 molecular weight membrane yielded two fractions.Both fractions caused hypersensitive necrosis on tobacco leaves,it was suggested that P.boehmeriae could secrete at least two kinds of protein elicitors,with different molecular weight.The protein elicitor with molecular weight larger than 30×10 3 was given an intensively study in this work.Boiled in 100 ℃ water for 5 min,the elicitor still could induce HR in tobacco;Treated with protease K,the elicitor lost its activity,that means the protein domain is the activity part;After diluted about 1 000 times,the elicitor could still induce tobacco resistance to TMV about 80%.It was indicated that, P.boehmeriae could secrete a novel protein elicitor with molecular weight larger than 30×10 3,which could induce HR in tobacco and its activity was determined by protein domain.A highest protein accumulation was given after ten days′ culture.