籽用美洲南瓜白粉病病原菌生理小种鉴定及抗性遗传分析

利用形态学和分子生物学的方法对内蒙古不同地区籽用美洲南瓜白粉病病原菌种类进行鉴定，并采用国际通用的13 个甜瓜生理小种鉴别寄主和鉴别标准体系，对不同地区白粉病菌的生理小种进行鉴定。对20 份籽用美洲南瓜种质的抗病性进行鉴定，并采用苗期人工接种的方法对籽用美洲南瓜六世代群体进行抗性统计分析，开展白粉病抗性遗传研究。形态学鉴定结果表明，籽用美洲南瓜白粉病病菌具有成串的椭圆形分生孢子，具有纤维状体。系统发育树鉴定结果表明该白粉病菌ITS 序列与GenBank 中已公布的瓜类单囊壳白粉菌（Podosphaera xanthii）的序列聚在一个分枝，确定内蒙古地区白粉病菌为单囊壳白粉菌P. xanthii。初步确定内蒙古地区籽用美洲南瓜白粉病存在4 个生理小种，分别为小种4、小种2F 和小种1，还有1 个未知的小种。种质抗性鉴定结果表明，20 份籽用美洲南瓜种质中有7 份抗病种质，4 份中抗种质，1 份高抗种质。内蒙古地区籽用美洲南瓜抗白粉病基因由1 对主效隐性单基因控制。

Identification of Powdery Mildew Physiological Race in Seed-used Pumpkin Cucurbita pepo L.）and Genetic Analysis of Its Resistance

Identification was carried out on powdery mildew pathogenic species of seed-used pumpkin Cucurbita pepo L.）from different regions of Inner Mongolia by morphology and molecular biology ethods．The physiological race of powdery mildew from different regions were identified by using the nternational common used 13 different identification hosts of powdery mildew and identification system．The resistance of 20 seed-used pumpkin germplasms was evaluated，and statistical analysis on 6 generations rogeny resistance was carried out using artificial inoculation method at the seedling stage．Studies on genetic esistance of powdery mildew was also carried out．The results of morphological identification indicated that he powdery mildew of seed-used pumpkin had bunchy ellipsoidal conidium having corpus fibronsum．The esult of molecular identification showed that the rDNA-ITS sequence of powdery mildew was in a branch with he sequence of Podsphaera xanthii，published in GenBank．The powdery mildew in Inner Mongolia region as identified as P. xanthii，and 4 physiological races of powdery mildew identified in Inner Mongolia region ere race 4，race 2F，race 1，and one unknown race．The test results of germplasm resistance showed that mong the 20 seed-used pumpkin germplasms 7 were disease-resistant，4 with medium-resistance，and 1 with igh-resistance．The powdery mildew resistance genes of seed-used pumpkin in Inner Mongolia region were ontrolled by a pair of major recessive single gene．