AGGRESSIVENESS OF FUSARIUM SPECIES CAUSING HEAD BLIGHT IN BARLEY LANDRACES GROWN UNDER FERTILE CRESCENT CONDITIONS

Abstract

Aggressiveness assessment of Fusarium head blight (FHB) is crucial for understating the interaction between host and pathogen in the Hordeum vulgare-FHB system. More effective and accurate disease evaluation methods should be sought for successful identification of pathogenic variation in FHB species. In order to achieve this objective, a pot experiment under natural climatic conditions over two growing seasons 2017/18 and 2018/19 was conducted to evaluate aggressiveness on a set of 16 fungal isolates of four Syrian FHB species. Then, the current findings were compared with previous analyzed in vitro and growth chamber data. Pathogenic variation was quantified as disease development rates, disease incidence (DI) and Fusarium-damaged kernels (FDK) on two barley landraces widely cultivated along the Fertile Crescent: Arabi Aswad (AS) and Arabi Abiad (AB) varying in resistance to FHB causing agents. All tested FHB species caused disease symptoms on the two barley landraces; and FHB disease progressed slowly and less severally as generally observed on AS compared with AB. Regarding DI, there were significant differences in aggressiveness intra- and inter-species and in susceptibility between AS and AB. FDK criterion did not differentiate FHB isolates and the two tested landraces. The values of DI were significantly correlated with pathogenicity traits previously obtained in vitro and under controlled conditions over the two growing seasons. Our current findings confirmed previous in vitro and growth chamber data that AS exhibits higher resistance levels to initial fungal infection compared to AB. AS may be a new source for livestock and AB for malting and brewing resistance breeding programs because of their resistance to FHB. To our best knowledge, this is the first report investigating both: pathogenicity on AS and AB grown under Fertile Crescent conditions and potential use of in vitro and growth chamber aggressiveness indices in predicting FHB data generated under natural climatic conditions in barley.