Postulation of virulence groups and resistance factors in the quinoa/downy mildew pathosystem using material from Ecuador

Resumen

Twenty downy mildew isolates were collected in south, central and north Ecuador and inoculated on seedlings of 60 quinoa lines. A scale for scoring quinoa downy mildew infections was developed. Four virulence groups and three resistance factors were identified. In southern Ecuador only isolates of virulence group 2 were collected, while in the central region only virulence group 4 was found. In the north of Ecuador isolates of all four virulence groups were collected. Resistance factor R3 was found most frequently in seedlings of 13 high‐yielding Ecuadorian quinoa lines. No effective resistance against group 4, the most virulent group, was observed. Lines ECU‐288 (susceptible), ECU‐291(R1), ECU‐470 (R2) and ECU‐379 (R3) could be used as a preliminary quinoa differential set for identifying downy mildew virulence groups.