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In the present work, the major physiological and compositional changes occurring during 'Merrill O'Henry' peach growth and its relationship with susceptibility to three strains of Monilinia spp. at 49, 77, 126 and 160 days after full bloom were explored. Results of disease incidence indicated wide differences among phenological stages, being 49 and 126 days after full bloom the moment when peaches showed significantly lower susceptibility to brown rot (40 and 23% of rotten fruit, respectively, for strain ML8L). Variation in brown rot susceptibility among different growth stages was also strain-dependent. Lower fruit susceptibility to ML8L at 49 and 126 was accompanied by noticeable changes in the fruit ethylene and respiration patterns, and also in sugars and organic acids content. By employing a partial least squares regression model, a strong negative relationship between citric acid, and a positive association of ethylene with peach susceptibility to Monilinia spp. at diverse phenological stages were observed. The results obtained herein highlight that the content of certain compounds such as citrate, malate and sucrose; the respiratory activity and the fruit ethylene production may mediate in a coordinated manner the fruit resistance to Monilinia spp. at different phenological stages of peach fruit.

Monilinia spp. may infect stone fruit at any growth stage, although susceptibility to brown rot depends on both host properties and climatological conditions. This said, no studies deciphering the host response in the interaction between peach blossoms and Monilinia spp. are yet available. This study presents an in-depth characterization of the role of ethylene in the interaction of 'Merrill O'Henry' peach petals (Prunus persica (L.) Batch) with Monilinia laxa and M. fructicola. We investigated the physiological responses of the host and the fungi to the application of ethylene and 1-methylcyclopropene (1-MCP) as well as the molecular patterns associated with the biosynthetic and ethylene-dependent responses during the interaction of both Monilinia species with the host. The incidence of both species was differentially affected by 1-MCP and ethylene; M. laxa was favoured by the enhanced host ethylene production associated with the treatments whereas M. fructicola reduced its infection capacity. Such differences were host-dependent as treatments did not affect growth or colony morphology of Monilinia spp. Besides, host ethylene production was altered in M. laxa inoculated petals, either by the fungus or the host itself. Molecular analysis revealed some important ERFs that could be involved in the different ability of both species to activate a cascade response of peach petals against these pathogens., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Controversy exists on whether ethylene is involved in determining fruit resistance or susceptibility against biotic stress. In this work, the hypothesis that ethylene biosynthesis in peaches at different phenological stages may be modulated by Monilinia spp. was tested. To achieve this, at 49 and 126 d after full bloom (DAFB), ethylene biosynthesis of healthy and infected 'Merryl O'Henry' peaches with three strains of Monilinia spp. (M. fructicola (CPMC6) and M. laxa (CPML11 and ML8L) that differ in terms of aggressiveness) was analysed at the biochemical and molecular level along the course of infection in fruit stored at 20 °C. At 49 DAFB, results evidenced that infected fruit showed inhibition of ethylene production in comparison with non-inoculated fruit, suggesting that the three Monilinia strains were somehow suppressing ethylene biosynthesis to modify fruit defences to successfully infect the host. On the contrary, at 126 DAFB ethylene production increased concomitantly with brown rot spread, and values for non-inoculated fruit were almost undetectable throughout storage at 20 °C. The expression of several target genes involved in the ethylene biosynthetic pathway confirmed that they were differentially expressed upon Monilinia infection, pointing to a strain-dependent regulation. Notably, Prunus persica 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) (PpACS) family was the most over-expressed over time, demonstrating a positive ethylene regulation, especially at 126 DAFB. At this phenological stage it was demonstrated the ability of Monilinia spp. to alter ethylene biosynthesis through PpACS1 and benefit from the consequences of an ethylene burst likely on cell wall softening. Overall, our results put forward that infection not only among different strains but also at each stage is achieved by different mechanisms, with ethylene being a key factor in determining peach resistance or susceptibility to brown rot., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Background: Monilinia spp. are responsible for brown rot, one of the most significant stone fruit diseases. Planting resistant cultivars seems a promising alternative, although most commercial cultivars are susceptible to brown rot. The aim of this study was to explore resistance to Monilinia fructicola over two seasons in a backcross one interspecific population between almond 'Texas' and peach 'Earlygold' (named T1E)., Results: 'Texas' almond was resistant to brown rot inoculation, whereas peach was highly susceptible. Phenotypic data from the T1E population indicated wide differences in response to M. fructicola. Additionally, several non-wounded individuals exhibited resistance to brown rot. Quantitative trait loci (QTLs) were identified in several linkage groups, but only two proximal QTLs in G4 were detected over both seasons and accounted for 11.3-16.2% of the phenotypic variation., Conclusion: Analysis of the progeny allowed the identification of resistant genotypes that could serve as a source of resistance in peach breeding programs. The finding of loci associated with brown rot resistance would shed light on implementing a strategy based on marker-assisted selection (MAS) for introgression of this trait into elite peach materials. New peach cultivars resistant to brown rot may contribute to the implementation of more sustainable crop protection strategies. © 2019 Society of Chemical Industry., (© 2019 Society of Chemical Industry.)

Background: Brown rot caused by Monilinia spp. is one of the most important postharvest diseases of stone fruit. The aim of this study was to evaluate the relevance of the main postharvest operations of fruit - hydrocooling, cold room, water dump, sorting and cooling tunnel - in the development of M. laxa on peaches and nectarines artificially infected 48, 24 or 2 h before postharvest operations., Results: Commercial hydrocooling operation reduced incidence to 10% in 'Pp 100' nectarine inoculated 2 and 24 h before this operation; however, in 'Fantasia' nectarine incidence was not reduced, although lesion diameter was decreased in all studied varieties. Hydrocooling operation for 10 min and 40 mg L -1 of sodium hypochlorite reduced brown rot incidence by 50-77% in nectarines inoculated 2 h before operation; however, in peach varieties it was not reduced. Water dump operation showed reduction of incidence on nectarine infected 2 h before immersion for 30 s in clean water at 4 °C and 40 mg L -1 sodium hypochlorite; however, in peach varieties it was not reduced. Cold room, sorting and cooling tunnel operation did not reduce brown rot incidence., Conclusion: From all studied handling operations on stone fruit packing houses, hydrocooling is the most relevant in the development of brown rot disease. Duration of the treatment seems to be more important than chlorine concentration. In addition, hydrocooling and water dump were less relevant in peaches than in nectarines. As a general trend, hydrocooling and water dump reduced incidence on fruit with recent infections (2 or 24 h before operation); however, when infections have been established (48 h before operation) diseases were not reduced. © 2017 Society of Chemical Industry., (© 2017 Society of Chemical Industry.)

The development of brown rot in stone fruit caused by the necrotrophic fungus Monilinia spp. is influenced by many abiotic factors, such as temperature, humidity, and light. Specifically, filamentous fungi perceive light as a signal for ecophysiological and adaptive responses. We have explored how specific light wavelengths affect the in vitro development, the regulation of putative development genes and the virulence of the main species of Monilinia (M. laxa , M. fructicola and M. fructigena). After subjecting Monilinia spp. to different light wavelengths (white, black, blue, red, far-red) for 7 days, several differences in their phenotype were observed among light conditions, but also among species. These species of Monilinia exhibited a different phenotypic plasticity in response to light regarding pigmentation, growth, and specially conidiation of colonies. In this sense, we observed that the conidial production was higher in M. laxa than M. fructicola , while M. fructigena showed an inability to produce conidia under the tested conditions. Growth rate among species was significantly lower in M. fructicola under red light wavelength while among light conditions it was increased under far-red light wavelength for M. laxa and under black light for M. fructicola ; in contrast, no statistical differences were observed for M. fructigena. Gene expression analysis of 13 genes involved in fungal development of Monilinia spp. revealed a significant difference among the three species of Monilinia , and especially depended on light wavelengths. Among them, a high expression of OPT1 , RGS2 , RGS3 and SPP1 genes was observed in M. laxa , and LTF1 and STE12 in M. fructicola under black light. In contrast, a high expression of REG1 and C6TF1 genes occurred in both M. fructicola and M. laxa subject to red and far-red light wavelength, respectively. When nectarines were artificially infected with M. laxa and M. fructicola subjected to black light, the virulence was clearly reduced, but not in M. fructigena. Overall, results presented herein demonstrate that light wavelengths are a key abiotic factor for the biology of Monilinia spp., specially modulating its capacity to form conidia, and thus, influencing its spreading and the onset of the disease on nectarines during postharvest. • M. laxa and M. fructicola present a similar behaviour, but not M. fructigena. • The conidial production is higher in blue light for M. laxa and M. fructicola. • M. fructicola growth rate is reduced under red light compared to the other species. • Virulence in nectarines decreases in M. laxa and M. fructicola under black light. • M. fructigena reveals a similar behaviour among darkness and light wavelengths. [ABSTRACT FROM AUTHOR]