Lee T Y, Mizubuti E, Fry W E
Department of Plant Pathology, Cornell University, 334 Plant Science Building, Ithaca, New York 14853, USA.
Fungal Genet Biol. 1999 Mar;26(2):118-30. doi: 10.1006/fgbi.1998.1107.
Several sexual crosses involving isolates of Phytophthora infestans of diverse sensitivities to metalaxyl were studied. Metalaxyl sensitivity was determined by comparing the growth of an isolate on metalaxyl-amended agar medium (5 microg/ml) with growth on medium containing no metalaxyl. When both parents had the same phenotype for metalaxyl sensitivity (both resistant or both sensitive), all F1 progeny had the parental phenotype. In two crosses (75 and 76) each involving one sensitive and one resistant parent, however, the progeny segregated 1:1, suggesting that the common resistant parent (Bg8) was heterozygous for metalaxyl sensitivity. When an F2 progeny was constructed from resistant F1 isolates in cross 76, the progeny segregated 1:3 (sensitive:resistant), indicating that metalaxyl resistance in Bg8 is conferred by a single dominant gene. Variation in the progeny sensitivity appears to involve minor genes. A correlation study between metalaxyl resistance and fitness components did not reveal any association.
对几种涉及对甲霜灵敏感性不同的致病疫霉分离株的有性杂交进行了研究。通过比较分离株在添加甲霜灵的琼脂培养基（5微克/毫升）上的生长情况与在不含甲霜灵的培养基上的生长情况来确定甲霜灵敏感性。当双亲对甲霜灵敏感性具有相同表型（均抗性或均敏感）时，所有F1后代都具有亲本表型。然而，在两个杂交组合（75和76）中，每个组合都涉及一个敏感亲本和一个抗性亲本，后代以1:1的比例分离，这表明常见的抗性亲本（Bg8）对甲霜灵敏感性是杂合的。当从杂交组合76中的抗性F1分离株构建F2后代时，后代以1:3（敏感:抗性）的比例分离，表明Bg8中的甲霜灵抗性由单个显性基因控制。后代敏感性的变化似乎涉及微效基因。甲霜灵抗性与适合度组分之间的相关性研究未发现任何关联。
