Wheat blast caused by Magnaporthe oryzae pathovar Triticum is efficiently controlled by the plant defence inducer isotianil

Abstract

Wheat blast caused by Magnaporthe oryzae pv. Triticum is an upcoming threat to wheat cultivation worldwide. The disease crossing over to wheat first gained attention in South America, with increasing interest coming from its more recent appearance in the big wheat-growing areas of Asia. The increasing economic relevance of the disease and the lack of genetic resistance in current wheat breeding material, besides fungicide resistance already present in fungal pathogen populations, highlighted the need to evaluate the potential of isotianil as an alternative plant protection measure. Isotianil is already registered in Asia for the protection of rice against M. oryzae, but because the agronomic practices and disease development of blast differ between rice and wheat, the efficacy of isotianil against wheat blast was hard to predict. Testing isotianil in the currently available formulations, applied either as seed treatment or soil drench, resulted in a significant reduction of disease severity. The efficacy was comparably high, on different wheat cultivars and using several fungal isolates with different degrees of virulence. Microscopic analyses revealed that isotianil treatment can prevent invasive growth of the pathogen. No phytotoxicity from isotianil treatment was observed on wheat plants. Importantly, isotianil not only protects wheat plants at the seedling stage but also on spikes thereby preventing losses due to this most severe disease syndrome. In summary, the results showed the high potential of isotianil to protect against wheat blast.

Testing Effects of Seed Treatments against Clubroot Disease in Various Oilseed Rape Hybrids

“…In this sense, Lahlali et al [39,40] found that mechanistically, the determination of the expression of selected defense genes pointed to the activation of JA-and ET-related defense pathways in B. napus. A similar mechanism to induce defense is associated with the compound isotianil [17][18][19]. Therefore, we could show that both control agents are potential new tools to reduce clubroot disease in oilseed rape.…”

“…However, its particular mode of action was better understood only during the last decade. Bektas and Eulgem [18] as well as Portz et al [19] showed that isotianil can act like an elicitor that mimics salicylic acid with significant activity against blast diseases in rice and wheat but without having a direct effect against these diseases. Similarly, isotianil can help to reduce difficult-to-control diseases like Fusarium wilt of banana caused by the fungal agent Fusarium oxysporum f. sp.…”

5,5′-Thiobis(3-bromoisothiazole-4-carbonitrile)

“…Their applications, chemistry and synthesis have been reviewed [17][18][19]. Examples of biologically useful isothiazoles are the fungicide isotianil (Stout ® ) [20,21], active against rice blast, and the antibacterial drug sulfasomizole [22,23].…”

In-silico prediction of highly promising natural fungicides against the destructive blast fungus Magnaporthe oryzae

“…The control of blast disease is difficult and mainly achieved through the use of chemical fungicides [ 5 , 25 ]. However, extensive use of chemical fungicides has resulted in development of resistance in fungus against the fungicides [ 5 , 11 , 45 ]. Resistance sources for breeding blast resistance are limited in some cases such as in wheat.…”