A 90 kDa protein elicitor, PB90, was purified from the culture filtrate of Phytophthora boehmeriae. Procedures including hydrophobic interaction and ion-exchange chromatography were used to purify the protein. PB90 induced hypersensitive reaction in tobacco leaves at a concentration as low as 200 pM and induced systemic acquired resistance (SAR) to TMV, Alternaria alternata, P. parasitica and Ralstonia solanacearum. In addition, it also caused hypersensitive necrosis in leaves of Chinese cabbage and induced SAR to Collectorium higginsianum in the plant. Tobacco leaves infiltrated with 200 pM of the elicitor exhibited an enhanced phenylalanine ammonia lyase activity and peroxidase activity. The behavior on ion-exchange columns indicated that PB90 is an acidic protein. It is stable to heat, acidic and alkaline conditions, but sensitive to ProteaseK. An antiserum raised against the pure protein allowed localization of PB90 by immunogold labeling on the cell wall of the mycelia and encysting zoospores when the fungus is grown in vitro. It was implied that there is a novel protein elicitor secreted by P. boehmeriae, which has a broad activity spectrum. The characters of PB90 distinguished it clearly from the other elicitors previously identified from Phytophthora spp. The possible implications of such a novel elicitor in plant–microbe interactions are discussed.

将江苏省20个不同小种稻瘟病菌菌株在白米玫瑰红培养基上对峙培养测定营养体亲和性，25℃、黑暗中对峙培养18d，在173个配对组合中有124个配对组合的菌株之间，通过菌丝融合在菌落交界处形成肉眼可见的菌丝融合带，在49个配对组合不能形成明显的菌丝融合带，表明江苏省不同来源的稻瘟病菌菌株间存在较普遍的营养体亲和性。将分别携有抗稻瘟灵、对多菌灵敏感（MBCsIPTr），以及对稻瘟灵敏感、抗多菌灵（MBCrIPTs）标记的菌株对峙培养，切取菌丝融合带进行单菌丝片段分离，从其无性系中获得了经菌丝融合产生的携带双亲抗性标记的（MBCrIPTr）的无性重组体。在检测的17个不同小种菌株配对的组合中，有13个组合可获得无性重组体。不同配对组合菌株间无性重组频率为0.6%～11.3%。表明营养体亲和在江苏省稻瘟病菌中发生较为普遍。

野生型烟草Bel-W3叶片经棉疫病菌90kD蛋白激发子处理后，处理叶及其上位叶在24h内均发生2次氧化迸发产生H2O2，且第二次H2O2迸发高峰期同时出现，均出现在第12小时，处理部位细胞死亡高峰期比第二次H2O2迸发高峰期滞后8h。引起过敏反应剂量的激发子诱发反义抑制抗坏血酸过氧化物酶anti-APX烟草的过敏性坏死枯斑比野生型的大而且出现得早；不能诱发野生型烟草HR的剂量可以诱导anti-APX烟草发生HR。经激发子处理后anti-APX烟草对烟草疫霉（Phytophthoranicotianae）和TMV产生的诱导抗性比其野生型高。上述结果表明，H2O2可能是一种重要的信号分子，在棉疫病菌90kD蛋白激发子诱发烟草的HR和SAR中具有重要作用，但可能不是一种可以系统移动的信号分子。

Colony-type stability of asexual progeny of selfed-oospore cultures of Phytophthora cinnamomi was investigated. Progeny wcre divided into parental type A, types B to E for those different from type A but with a distinct uniform pattern, and type M for those with the overlapping appearance of two different types. Colonies derived from three successive zoospore generations of isolate P630 were of the same parental A type. However, colonies from oospores of the same isolate consisted of types A, B, C, D, E, and M. Some of the oospore cultures of type A or B and all the type M oospore cultures produced zoospores containing more than one type. Oospore cultures of types C, D, or E that were tested produced zoospores with the same colony type as their respective parent. Among the five cultures randomly selected from asexual progeny produced by oospore isolates P630-21 and P630-6, four displayed continuing variation in colony type in the three to five successive zoospore generations tested.

將一株同宗配合的Phytophthora cinnamomi菌株培養於含有殺菌劑chloroncb之洋菜培養基中，在3星期內形成快速生長之抗藥扇形面。分離自抗藥扇形面之抗藥菌株於菌落形態上與原來菌株具有平展（F）型，但其游走孢子菌株中，產生具有棉花（C）型菌落之抗藥菌株及F型菌株具有抗藥性及感藥性，C型菌株連續三代之游走孢子菌株均含有F型回復感藥菌株。雖然F型回復感藥菌株之游走孢子菌株均為相同形態之菌落，但經chloroneb處理在較短時間內可產生更多抗藥扇形面。分離自這些抗藥扇形面之游走孢子菌株為C型抗藥性和F型抗藥性或感藥性。C，u，F型抗藥菌株之游走孢子菌株均與前述的結果一樣表現不穩定。C和F型抗藥菌株形成之游走孢子大多（89—99%）具有单一细胞核。