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Detection of genetic variation among Endocronartium harknessii populations in British Columbia using rDNA RFLPS and RAPD markers Sun, Li-Juan

Abstract

DNA-level variability in Endocronartium harknessii (Moore) Hiratsuka, the cause of western gall rust On lodgepole pine (Pinus contorta Dougl.), was assessed using RAPD's and RFLP's. The material analyzed consisted of aeciospores from 120 wild isolates collected at 12 geographically separate locations (10 galls each) ranging from the interior (6 locations) to the coast (4 locations) of the province of British Columbia with two collections from Manning Park, representing one of the passes between these regions. Using the RAPD technique, of 180 primers screened, 64 yielded clear polymorphic bands. Of these 13 were chosen for the main study. These 13 primers yielded 96 polymorphic bands. All galls exhibited a unique RAPD-type. Principle Component Analysis (PCA) revealed that coastal and interior collections were quite distinct, with the exception of two adjacent interior collections (Quesnel and Ten Mile Lake). On the other hand, of the two collections from Manning Park, the high elevation one was clearly related to the interior population, while the low elevation one was clearly coastal indicating that there is probably limited gene flow between the two regions. Dendrograms constructed, using unweighted pair group arithmetic mean analysis (UPGMA) based on similarity measure for individual galls separated most local collections into distinct clusters, and revealed relationships between local collections similar to PCA. The RFLP technique was used for a small sample of galls and revealed considerable variation between them. However, since this technique was rather laborious and required larger amounts of DNA than could be extracted from spores produced by small, young, clean galls, it was not suitable for a large population study. Analysis of DNA from different sectors of large old galls using RAPD's showed some polymorphisms between sectors. The origin of these polymorphisms is not clear, A species-specific dsRNA was detected in several galls, as well as in collections of related Cronartium rusts, suggesting the presence of a mycovirus in these rust populations.

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