Fungicide resistance characterized across seven modes of action in Botrytis cinerea isolated from Australian vineyards

Abstract

BACKGROUND: Botrytis bunch rot, caused by Botrytis cinerea, is an economically important disease of grapes in Australia and across grape-growing regions worldwide. Control of this disease relies on canopy management and the application of fungicides. Fungicide application can lead to the selection of resistant B. cinerea populations, which has an adverse effect on the management of the disease. Characterizing the distribution and severity of resistant B. cinerea populations is needed to inform resistance management strategies.RESULTS: In this study, 724 isolates were sampled from 76 Australian vineyards during 2013-2016 and were screened against seven fungicides with different modes of action (MOAs). The resistance frequencies for azoxystrobin, boscalid, fenhexamid, fludioxonil, iprodione, pyrimethanil and tebuconazole were 5%, 2.8%, 2.1%, 6.2%, 11.6%, 7.7% and 2.9%, respectively. Nearly half of the resistant isolates (43.8%) were resistant to more than one of the fungicides tested. The frequency of vineyards with at least one isolate simultaneously resistant to one, two, three, four or five fungicides was 19.7%, 7.9%, 6.6%, 10.5% and 2.6%. Resistance was associated with previously published genotypes in CytB (G143A), SdhB (H272R/Y), Erg27 (F412S), Mrr1 (D354Y), Bos1 (I365S, N373S + Q369P, I365S + D757N) and Pos5 (V273I, P319A, L412F/V). Novel genotypes were also described in Mrr1 (S611N, D616G), Pos5 (V273L) and Cyp51 (P347S). Expression analysis was used to characterize fludioxonil-resistant isolates exhibiting overexpression (6.3-9.6-fold) of the ABC transporter gene AtrB (MDR1 phenotype).CONCLUSION: Resistance frequencies were lower when compared to most previously published surveys of B. cinerea resistance in grape and other crops. Nevertheless, continued monitoring of critical MOAs used in Australian vineyards is recommended.

Use of oxathiapiprolin for controlling soybean root rot caused by Phytophthora sojae: efficacy and mechanism of action

“…Three replicates for each concentration were used and the experiment was performed three times. The 50% effective concentration (EC 50 ) was determined as described previously 24 …”

Agroecological Management of the Grey Mould Fungus Botrytis cinerea by Plant Growth-Promoting Bacteria

“…These botrycides can be classified according to their mode of action into five categories as follows: (1) fungicides affecting fungal respiration; (2) anti-microtubule toxicants; (3) compounds affecting osmoregulation; (4) fungicides whose toxicity is reversed by amino acids; and (5) sterol biosynthesis inhibitors [ 9 , 12 , 13 ]. However, even when there is a wide variety of botrycides with different modes of action, the presence of resistant B. cinerea strains may occur, as this fungus may generate and accumulate mutations in its genome that allow its survival in the environment, resulting in relevant damages to crops around the world [ 14 ]. In addition to resistance to chemical botrycides, consumers prefer organic products that do not include the use of pesticides during their production.…”

Rational design and identification of novel thiosemicarbazide derivatives as laccase inhibitors

“…The control of fungi in plants depends largely on the use of fungicides. However, due to the overusing of pesticides in the past decades, pathogenic fungi have developed resistance, which restrict the use of many fungicides, therefore it is urgent to develop new structures and new targets of fungicides 5,6 …”

“…However, due to the overusing of pesticides in the past decades, pathogenic fungi have developed resistance, which restrict the use of many fungicides, therefore it is urgent to develop new structures and new targets of fungicides. 5,6 Laccase (EC 1.10.3.2) is extremely important for pathogenic fungi and is involved in various biochemical reactions of fungal cells, such as fungal cell growth and development, morphogenesis, and defense systems. [7][8][9][10][11][12] Moreover, laccase is a key enzyme in the fungal 1,8-dihydroxynaphthalene (DHN) melanin biosynthetic pathway.…”