Components of quantitative resistance to Fusarium head blight agents in durum and bread wheat plants grown under Mediterranean conditions

Abstract

Fusarium head blight (FHB) is one of the major damaging fungal diseases affecting wheat production globally. As a basis for progress in devising future management strategies for FHB in wheat, it is necessary to identify resistant wheat cultivars to disease infection and determine whether their stability varies over several experimental conditions. A pot experiment under open field Mediterranean conditions over two growing seasons 2017/18 and 2018/19 was conducted to evaluate components of quantitative resistance to a set of 16 fungal isolates of four FHB species. Disease-type I resistance, disease-type II resistance as well as disease-type III resistance were compared on two Syrian durum and bread wheat cultivars varying in their FHB resistance. Douma4 (bread), rather resistant in vitro and under controlled conditions, showed greater FHB disease-type I and II resistance than Cham7 (durum), which showed a susceptibility to disease. There were no significant differences in the resistance of two wheat cultivars as measured by disease-type III. As expected, these results confirmed previous in vitro and growth chamber findings, indicating that the assessment of resistance level is repeatable and stable under several experimental conditions. Overall, the two tested wheat cultivars were shown to exhibit acceptable resistance levels to FHB infection. Differences in aggressiveness among fungal isolates and susceptibility/resistance among wheat cultivars were found, emphasizing that screening for wheat resistance to FHB requires the use of aggressive fungal isolates or a mixture of several isolates. While in the Mediterranean countries the risk of disease is progressively increasing, the preliminary data in this report show that Syrian commercial cultivars could be new resistant donors with favorable agronomical characteristics in FHB-wheat breeding programs.