Gutiérrez Walter A, Mila Asimina L
Department of Plant Pathology, North Carolina State University, Raleigh 27695.
Plant Dis. 2007 Aug;91(8):985-989. doi: 10.1094/PDIS-91-8-0985.
A laboratory technique for determining races of Phytophthora nicotianae on tobacco (Nicotiana tabacum) was developed and compared with a commonly used greenhouse method. The laboratory technique was based on production and inoculation of tobacco seedlings in tissue culture plates. Three P. nicotianae isolates from North Carolina previously determined as race 0 and 1 were used. Four tobacco cultivars and two breeding lines with different types of resistance were used as differential cultivars: K-326, K-346, NC-71, NC-1071, L8, and Ky14xL8. Plants were evaluated 7 and 14 days after inoculation. Five differential cultivars (K-326, K-346, NC-1071, NC-71, and L8) were determined to be sufficient to differentiate races 0 and 1. Cv. Ky14xL8 was ineffective for differentiation of races and produced inconsistent results. The laboratory technique was as effective as the greenhouse technique for distinguishing different races of P. nicotianae for every isolate in all experiments. Additionally, the most reliable results for both methods were obtained when evaluations were made 14 days after inoculation. The laboratory technique was validated with 21 isolates collected from four counties in North Carolina. The laboratory technique produced results 2 weeks faster than the greenhouse technique and required significantly less space and labor than the greenhouse technique for the same number of isolates. Additionally, the larger number of seedlings used in the laboratory technique increased the robustness of the results, especially for isolates for which race identification was unclear with the greenhouse technique. We propose that the laboratory technique has the potential for evaluation of tobacco resistance in other pathosystems as well.
开发了一种用于确定烟草疫霉在烟草（Nicotiana tabacum）上菌系的实验室技术，并与常用的温室方法进行了比较。该实验室技术基于在组织培养板中培育和接种烟草幼苗。使用了先前确定为0号和1号菌系的来自北卡罗来纳州的3个烟草疫霉分离株。使用4个烟草品种和2个具有不同抗性类型的育种系作为鉴别品种：K-326、K-346、NC-71、NC-1071、L8和Ky14xL8。在接种后7天和14天对植株进行评估。确定5个鉴别品种（K-326、K-346、NC-1071、NC-71和L8）足以区分0号和1号菌系。品种Ky14xL8在区分菌系方面无效，结果不一致。在所有实验中，对于每个分离株，该实验室技术在区分烟草疫霉不同菌系方面与温室技术一样有效。此外，两种方法在接种后14天进行评估时都能获得最可靠的结果。用从北卡罗来纳州4个县收集的21个分离株对该实验室技术进行了验证。该实验室技术比温室技术产生结果快2周，对于相同数量的分离株，所需空间和劳动力比温室技术少得多。此外，实验室技术中使用的大量幼苗增加了结果的稳健性，特别是对于用温室技术菌系鉴定不明确的分离株。我们认为该实验室技术也有潜力用于评估其他病理系统中的烟草抗性。
