Phytopathology. 2003 Mar;93(3):293-304. doi: 10.1094/PHYTO.2003.93.3.293.
ABSTRACT One hundred two single zoospore isolates of Phytophthora infestans, derived asexually from four parental isolates of US-8 genotype and one isolate of US-1 genotype, were characterized for their virulence phenotypes to determine changes in virulence during asexual reproduction. Potato differentials, each containing a major gene for resistance to P. infestans (R1 to R11), were used to characterize the virulence patterns. Isolates were also characterized for mating type, glucose-6-phosphate isomerase (Gpi) banding pattern, and DNA fingerprints using probe RG57 to determine any genotypic changes in the single zoospore isolates. A subset of these single zoospore isolates was tested for response to mefenoxam to determine any shifts in sensitivity. Results showed that single zoospore isolates derived from parent PI-1 (US-8, 11 isolates) were identical to their parental virulence. Isolates derived from parent PI-191 (US-8, 29 isolates) showed some differences in virulence, mainly toward R8 and R9. Isolates derived from parent PI-126 (US-8, 14 isolates) demonstrated a higher level of virulence diversity. Isolates derived from parents PI-52 (US-1, 28 isolates) and PI-105 (US-8, 20 isolates) showed the highest level of virulence variability among the single zoospore isolates. Mating type, Gpi banding pattern, and DNA fingerprints for the single zoospore isolates were, in most cases, identical to the parental isolates. Single zoospore isolates showed different levels of sensitivity to mefenoxam. Virulence and other genetic changes during asexual reproduction are likely to play a major role in changing the race structure of P. infestans populations. This continuous change in the race structure is a serious problem and now poses a new challenge for utilization of race-specific resistance to manage late blight of potato.
摘要 为了确定无性繁殖过程中致病力的变化，从美国 8 型（US-8）4 个亲本分离株和 1 个 US-1 型亲本分离株的无性单游动孢子后代中，选择了 102 个单游动孢子分离株，对其致病力表型进行了鉴定。这些分离株的鉴定是基于对含有抗晚疫病菌（Phytophthora infestans）主要基因（R1 到 R11）的马铃薯鉴别品种的分析。还对交配型、葡萄糖-6-磷酸异构酶（Gpi）带型和使用 RG57 探针的 DNA 指纹图谱进行了分析，以确定单游动孢子分离株的任何基因型变化。这些单游动孢子分离株的一个子集被用于测试对甲霜灵的反应，以确定其敏感性是否发生变化。结果表明，从亲本 PI-1（US-8，11 个分离株）分离得到的单游动孢子分离株与亲本的致病力完全相同。从亲本 PI-191（US-8，29 个分离株）分离得到的分离株在致病力方面表现出一些差异，主要针对 R8 和 R9。从亲本 PI-126（US-8，14 个分离株）分离得到的分离株表现出更高水平的致病力多样性。从亲本 PI-52（US-1，28 个分离株）和 PI-105（US-8，20 个分离株）分离得到的分离株在单游动孢子分离株中表现出最高水平的致病力变异性。在大多数情况下，单游动孢子分离株的交配型、Gpi 带型和 DNA 指纹图谱与亲本分离株相同。单游动孢子分离株对甲霜灵的敏感性表现出不同水平。无性繁殖过程中的致病力和其他遗传变化可能在改变晚疫病菌种群的菌系结构方面发挥主要作用。这种菌系结构的持续变化是一个严重的问题，现在对利用特定菌系的抗性来防治马铃薯晚疫病构成了新的挑战。
