Comparison of Aggressiveness of Four fusarium spp. That cause Head blight on Bread wheat, Durum wheat and Barley

Abstract

Fusarium head blight (FHB) is a significant disease affecting wheat and barley and is caused by several Fusarium species. However, contradictory data is available about their comparative pathogenicity on small grain cereals. Also, little research have compared the pathogenicity of individual Fusarium isolates on different plant parts (heads vs. detached leaves, detached heads, and coleoptiles) on cereals. This study aimed to assess the comparative pathogenicity of four Fusarium species at the earliest and latest growth stages under artificial infection with eight bread wheat, durum wheat and barley cultivars with diverse quantitative resistance levels. Four Fusarium species (F. culmorum, F. verticillioides, F. solani, and F. equiesti) were identified using an aggressive index involving nine pathogenic components generated under in vitro, growth chamber and field conditions to explore the relationships among Fusarium fungi and cereal plants. All the 16 tested FHB isolates and species were found to be pathogenic and induced typical FHB symptoms on small plant parts and adult heads. High level of variation in aggressiveness was observed among isolates within the species tested. Nevertheless, there was a similar comparative pathogenicity among the four tested Fusarium species when testing on the head and small plant parts tests. The origin of FHB pathogens may play a crucial role in this pathogenic similarity. This study suggests that screening for resistance to FHB requires the use of aggressive isolates or a mixture of several isolates. In addition, it indicates a lack of adaptation of these four tested Fusarium species. Our data clarifies for the first time the nature of comparative pathogenicity of diverse FHB species on durum wheat. It will provide critical information for cereal breeders to develop and improve FHB-resistant cultivars.