Stability and Fitness of Anilinopyrimidine-Resistant Strains of Botrytis cinerea

Abstract

The fitness of anilinopyrimidine-resistant isolates of Botrytis cinerea compared with that of sensitive isolates, collected from vegetable crops in Greece during 2005, was investigated. Stability of resistance to anilinopyrimidine fungicides was determined after consecutive transfers of the fungal isolates on fungicide-free potato dextrose agar for 16 culture cycles or on fungicide-untreated cucumber seedlings for eight disease cycles. Results showed that after the consecutive transfers of the isolates either in vitro or in vivo sensitivity to cyprodinil was not changed significantly compared to the initial sensitivity in all the isolates tested, suggesting a stable genetically controlled trait. Fitness parameters measured were mycelial growth, spore production in vitro, osmotic sensitivity, virulence, spore production in vivo, percentage of spore germination, and competitive ability of the resistant isolates in four pairs with sensitive isolates both on artificial nutrient medium or on cucumber seedling plants. The measurements of the fitness components in individual isolates showed high variability within both sensitivity groups in all, except virulence, fitness components tested. As a group, resistant isolates showed significantly lower (P < 0.05) mycelial growth and virulence, while they were more osmotically sensitive than the sensitive isolates. In addition the resistant isolates showed higher (P < 0.05) spore production in vivo but there was no difference (P > 0.05) between the two sensitivity groups in spore production in vitro and in the percentage of spore germination. However, the correlation to test if there is any relationship between the values of each fitness component tested and the level of cyprodinil sensitivity of each isolate was for all, except the spore production in vivo, fitness components not significant (P > 0.05). This absence of significant correlation coefficient values suggests that the development of resistance to anilinopyrimidine fungicides did not affect the fitness of the resistant isolates. Competition of the resistant versus sensitive isolates was isolates-dependent, since in two of the isolate pairs the resistance frequency decreased significantly after five culture or disease cycles, while in the remaining two pairs resistance frequency increased significantly after five disease cycles or remained stable for one pair after five culture cycles on artificial nutrient media.

Screening of Botrytis cinerea isolates from vineyards in Israel for resistance to fungicides

“…High variability in fitness parameters among both AP-resistant and AP-sensitive isolates was observed in a previous study, and, as a group, resistant isolates showed reduced mycelial growth and virulence (Bardas et al 2008). In the present work, APresistant isolates that were also resistant to other fungicides grew significantly more slowly than the WT isolates and formed smaller lesions on bean leaves.…”

Spread of Botrytis cinerea Strains with Multiple Fungicide Resistance in German Horticulture

“…There was a high diversity of combinations of resistance mutations in German MR isolates, akin to the situation in the United States (Fernández-Ortuño et al, 2015). These and similar fungicide resistance mutations have sometimes been reported to impair the fitness of Botrytis isolates in the case of fenhexamid (Billard et al, 2012), boscalid (Lalève et al, 2013; Veloukas et al, 2014) and iprodione (Leroux et al, 2002) whereas in other studies no fitness reductions were found (Bardas et al, 2008; Fernández-Ortuño et al, 2013; Amiri et al, 2014; Veloukas et al, 2014). The availability of strains with simultaneous resistance to most or all of these fungicides provided the opportunity to analyse their combined effects on fitness by performing phenotypic comparisons of MR and sensitive field strains.…”

Reduced sensitivity to azoxystrobin is stable in Monilinia fructicola isolates

“…An approach to estimating the stability of resistance and fitness is the comparison of two data points: the current situation (we call here "the initial culture") with the last transfer (Bardas et al, 2008; 2014; Karaoglanidis and Thanassoulopoulos, 2002;Kim and Xiao, 2011;Vega and Dewdney, 2014), but additional data in different time point of transfers will provide a better understanding of the process (Zhan and McDonald, 2013). There is a high degree of variability in conidia production and usually the number of conidia shows linear and gradual changes between transfers (Cox et al, 2007;Fan et al, 2015;Laleve et al, 2014;Vega and Dewdney, 2014).…”