麻疫霉异宗配合变异株交配型的遗传

以化学农药氯唑灵诱变苎麻疫霉（ＰｈｙｔｏｐｈｔｈｏｒａｂｏｅｈｍｅｒｉａｅＳａｗａｄａ）的野生型菌株Ｅｃ－８获得异宗配合变异株，氯唑灵的有效诱变浓度为１０～３０μｇ／ｍＬ，以２０μｇ／ｍＬ处理３～８周效果最好。异宗配合变异株的交配型在单游动孢子或单菌丝片段后代均发生分离，出现了疫霉菌已知的全部５种交配型的个体。各交配型在单游动孢子无性系后代持续分离：Ａ１交配型菌株后代出现了Ａ１、Ａ２、Ａ０和Ａ１，Ａ２交配型，Ａ２交配型菌株后代出现了Ａ１、Ａ２、Ａ１Ａ２和Ａ０交配型，Ａ１，Ａ２交配型菌株后代出现了Ａ１、Ａ２、Ａ１Ａ２、Ａ０和Ａ１，Ａ２交配型，Ａ０交配型菌株后代出现了Ａ１、Ａ１Ａ２、Ａ０和Ａ１，Ａ２交配型，而部分回复为Ａ１Ａ２交配型的菌株后代也出现了Ａ１、Ａ２、Ａ１Ａ２、Ａ０和Ａ１，Ａ２５种交配型。８０％以上的变异株在１２°Ｃ、黑暗中贮存２个月后仍可保持其原有交配型，部分变异株在菌丝块移植继代培养７代后仍然保持异宗配合特性。对部分Ａ１交配型单孢株激素产生与接受类型的测定结果表明，Ａ１交配型变异株至少包括Ｓ１和Ｓ２两种性征类型。上述结果提示，疫霉属卵菌性别的产生可能是由同宗配合演化为异宗配合，并可能同时分化产生不

Mating type inheritance of heterothallic variants of Phytophthora boehmeriae induced by ethazol

WTBZIsolate Ec8 of homothallic Phytophthora boehmeriae was induced to heterothallic variation by treatment with the fungicide ethazol.The effective concentration to obtain heterothallic variants was 1030 g/mL and the best results were at 20 g/mL for 38 weeks.All five mating types were observed in single hyphal fragment or single zoospore progenies of most heterothallic variants.Each of the five mating types continuously separated in successive zoospore generations.Single zoospore isolates derived from A1 were of A1;A2;A1 ,Q]A2 and A0;from A2 were of A1;A2;A1A2 and A0;from A1 ,FQ]A2 were of A1;A2;A1 , A2;A1A2 and A0;from A0 were of A1;A1 , A2;A1A2 and A0;and from some A1A2 isolates reverted from heterothallic variants were of A1;A2;A1 , A2;A1A2 and A0.More than 80% heterothallic variants could maintain their original mating type after being stored at 12 C under dark condition for 2 months.The assay of hormone production and responsiveness to hormone indic ated that A1 type heterothallic variants at least belonged to two sexuality types:S1 and S2.Conversion from homothallism to heterothallism and resulting in different mating types is suggested as a possible evolutionary origin of sexes in Phytophthora.