Response of Thirteen Winter Wheat (Triticum Aestivum) Cultivars to Severe Stripe Rust (Puccinia Striiformis f. Sp. Tritici) Attack

Abstract

Stripe rust caused by Puccinia striiformis f. sp. tritici has become an increasing threat for wheat crops worldwide. In Romania, stripe rust showed in 2023 increased adaptation to higher temperatures and different virulence at various sites. We analyzed the response to this new stripe rust variant of twelve winter wheat cultivars released by the National Agricultural Research & Development Institute Fundulea - Romania and one historical check, at six locations that reported higher attacks in 2023. Cultivars showed significantly different disease scores, ranging from resistant to very susceptible. Four of the five resistant cultivars were related and probably carry the same resistance gene(s) and only one had a different genealogy. All the other eight cultivars were medium-susceptible and susceptible. This underlines the need for more diversity of resistance to stripe rust in the breeding program. Resistance gene Yr18, present in two of the tested cultivars did not offer a sufficient protection against stripe rust. Average grain yield was significantly correlated with stripe rust scores averaged over the six sites (r=-0.85). However, cultivars with similar disease scores had different yields, as illustrated by large deviations from the regression of yields on stripe rust scores. These deviations might reflect differences in yielding potential and/or in tolerance to the disease. Cumulating these traits with genetic resistance deserves attention in breeding programs.