Host Specialization not Detected Among Isolates of the EC-1 Lineage of Phytophthora infestans Attacking Wild and Cultivated Potatoes in Peru

Abstract

To determine whether populations of Phytophthora infestans attacking wild and cultivated potatoes in the highlands of Peru are specialized on their hosts of origin, we characterized isolates using several neutral markers, metalaxyl resistance and for aggressiveness in a detached leaf assay. One hundred and fifty-three isolates were collected from the northern and central highlands of Peru from different potato cultivars (both modern and native cultivars) and from different species of wild, tuber-bearing potatoes. All the isolates analyzed belonged to one of four clonal lineages that had been described previously in Peru: EC-1, US-1, PE-3 and PE-7. The EC-1 lineage (n = 133) was dominant and present in similar frequencies on wild and cultivated potatoes. PE-3 (n = 14) was found primarily on cultivated potatoes, with only one isolate coming from a wild host. US-1 (n = 2) and PE-7 (n = 4) were rare; all but one (PE-7) occurred on wild potatoes. Isolates from the EC-1 lineage from modern cultivars were compared in three separate detached leaf inoculation assays with EC-1 isolates from the wild potato species S. sogarandinum, S. bill-hookerii or S. huancabambense, respectively. No significant interactions between isolate type (from wild or cultivated potato) and host type (wild or cultivated) were measured for any assay. It appears that the pathogen genotypes in the EC-1 lineage indiscriminately attack both wild and cultivated tuber-bearing solanaceous hosts in Peru, and breeders should be able to select for resistance using the common EC-1 lineage.

Large subclonal variation in Phytophthora infestans populations associated with Ecuadorian potato landraces

“…More recently, in commercial varieties and selected clones from INIAP's national potato breeding programme, 27, 17 and 37 races were found in Carchi, Cotopaxi and Pichincha provinces, respectively (Tello, 2008). In Peru and Colombia three clonal lineages were identified that infected potato landraces (Garry et al, 2005;Vargas et al, 2009) and, as in Ecuador, the domi-nant lineage was EC-1. Some studies on P. infestans populations indicated a low genetic diversity, represented by a single dominant clonal lineage but with high virulence diversity Guo et al, 2009).…”

Population structure and host range of the potato late blight pathogen Phytophthora infestans in Peru spanning two decades

“…Table S1. Solanaceous species reported as hosts of Phytophthora infestans in Peru (Junchaya, 1983;Garry et al, 2005b). Table S2.…”

Population genetic analysis of Phytophthora infestans in northwestern China

“…Many studies throughout the world have indicated that P. infestans populations outside central Mexico were dominated by the ‘US‐1’ clonal lineage until the 1970s (Fry, ). The situation changed with the detection of the A2 mating type from several European countries in the early 1980s (Goodwin et al ., ; Garry et al ., ). Analysis of P. infestans populations in Europe indicated that the new population displaced the previous dominant population in only a few years and was further spread worldwide (Fry, ).…”