Biological properties of flutianil as a novel fungicide against powdery mildew

Abstract

Flutianil, chemically characterized as a cyano-methylene thiazolidine, showed antifungal activity against powdery mildew on various crops but not any other plant pathogens tested. Flutianil showed high residual and translaminar activities and rainfastness against Podosphaera xanthii. It also exhibited curative activity against P. xanthii on cucumber at an extremely low concentration of 10 mg/L. There was no cross-resistance between flutianil and other existing fungicides. Morphological studies revealed that flutianil did not inhibit the early infection behavior of Blumeria graminis f. sp. hordei i.e., conidium bursting, primary and appressorial germinations, appressorium development and hook formations, but it did inhibit haustorium formation and further fungal development. Nutrient absorption by haustoria and subsequent secondary hyphal elongation was inhibited by flutianil but not by the fungicide that showed a similar inhibitory pattern up to the haustorium formation stage of the infection process. These findings suggest that flutianil might have a novel mode of action.

Effect of flutianil on the morphology and gene expression of powdery mildew

“…Our previous report indicated that in the infection process of Bgh, flutianil inhibited the haustorial formation and the prevention of pathogen nutrient acquisition from the host cells. 13) In current studies, the most noteworthy morphological and ultrastructural changes as a result of treating Bgh with flutianil were in the haustoria. Flutianil causes the EHMa to be obscured, resulting in the HCW being obscured.…”

“…Our previous study indicated that on flutianil-treated leaves, conidiophores had formed abnormally as elongated tubes, but the collapse of conidiophores or mycelia was not observed. 13) These findings indicate that the morphological change in Bgh by treatment with flutianil is completely different from that by treatment with the existing fungicides cyflufenamid and metrafenone.…”

“…hordei (Bgh) by inhibiting its nutrient absorption from the host cell. 13) However, the biochemical target site of flutianil has not been completely clarified. In order to find the primary site of action of flutianil, a detailed analysis of the effect of flutianil on Bgh morphology was conducted using microscopic observation techniques with a transmission electron microscope.…”