Hu Chia-Hui, Perez Frances G, Donahoo Ryan, McLeod Adele, Myers Kevin, Ivors Kelly, Secor Gary, Roberts Pamela D, Deahl Kenneth L, Fry William E, Ristaino Jean B
Department of Plant Pathology, North Carolina State University, Raleigh, 27695.
United States Department of Agriculture-Agricultural Research Service (USDA-ARS) PSI-GIFVL, BARC-West, Beltsville, MD, 20705.
Plant Dis. 2012 Sep;96(9):1323-1330. doi: 10.1094/PDIS-03-11-0156-RE.
Isolates of Phytophthora infestans (n = 178) were collected in 2002 to 2009 from the eastern United States, Midwestern United States, and eastern Canada. Multilocus genotypes were defined using allozyme genotyping, and DNA fingerprinting with the RG-57 probe. Several previously described and three new mulitilocus genotypes were detected. The US-8 genotype was found commonly on commercial potato crops but not on tomato. US-20 was found on tomato in North Carolina from 2002 through 2007 and in Florida in 2005. US-21 was found on tomato in North Carolina in 2005 and Florida in 2006 and 2007. US-22 was detected on tomato in 2007 in Tennessee and New York and became widespread in 2009. US-22 was found in 12 states on tomato and potato and was spread on tomato transplants. This genotype accounted for about 60% of all the isolates genotyped. The US-23 genotype was found in Maryland, Virginia, Pennsylvania, and Delaware on both tomato and potato in 2009. The US-24 genotype was found only in North Dakota in 2009. A1 and A2 mating types were found in close proximity on potato and tomato crops in Pennsylvania and Virginia; therefore, the possibility of sexual reproduction should be monitored. Whereas most individuals of US-8 and US-20 were resistant to mefenoxam, US-21 appeared to be intermediately sensitive, and isolates of US-22, US-23, and US-24 were largely sensitive to mefenoxam. On the basis of sequence analysis of the ras gene, these latter three genotypes appear to have been derived from a common ancestor. Further field and laboratory studies are underway using simple sequence repeat genotyping to monitor current changes in the population structure of P. infestans causing late blight in North America.
2002年至2009年期间，从美国东部、美国中西部和加拿大东部采集了178株致病疫霉分离株。利用等位酶基因分型和RG - 57探针进行DNA指纹分析来确定多位点基因型。检测到了几种先前描述的和三种新的多位点基因型。US - 8基因型常见于商业马铃薯作物，但不见于番茄。2002年至2007年在北卡罗来纳州以及2005年在佛罗里达州的番茄上发现了US - 20。2005年在北卡罗来纳州以及2006年和2007年在佛罗里达州的番茄上发现了US - 21。2007年在田纳西州和纽约州的番茄上检测到了US - 22，并于2009年广泛传播。在12个州的番茄和马铃薯上发现了US - 22，且通过番茄移栽传播。该基因型占所有已分型分离株的约60%。于2009年在马里兰州、弗吉尼亚州、宾夕法尼亚州和特拉华州的番茄和马铃薯上发现了US - 23基因型。2009年仅在北达科他州发现了US - 24基因型。在宾夕法尼亚州和弗吉尼亚州的马铃薯和番茄作物上近距离发现了A1和A2交配型；因此，应监测有性繁殖的可能性。虽然US - 8和US - 20的大多数个体对甲霜灵耐药，但US - 21似乎中度敏感，而US - 22、US - 23和US - 24的分离株对甲霜灵大多敏感。基于ras基因的序列分析，后三种基因型似乎源自一个共同祖先。目前正在进行进一步的田间和实验室研究，利用简单序列重复基因分型来监测导致北美晚疫病的致病疫霉种群结构的当前变化。
