Glycosylated flavonoids: fruit's concealed antifungal arsenal

Abstract

Fruit defense against pathogens relies on induced and preformed mechanisms. The present contribution evaluated performed resistance of red and green mango fruit against the fungal pathogen Colletotrichum gloeosporioides and identified the main active antifungal components.High-performance liquid chromatography analysis of nonhydrolyzed mango peel extracts identified major anthocyanin peaks of glycosylated cyanidin and methylcyanidin, and flavonol peaks of glycosylated quercetin and kaempferol, which were more abundant on the 'red side' of red mango fruit. Organic extracts of red vs green mango peel were more efficient in inhibiting C. gloeosporioides.Transcriptome analysis of the mango-C. gloeosporioides interaction showed increased expression of glucosidase genes related to both fungal pathogenicity and host defense. Glucosidase treatment of organic peel extract increased its antifungal activity. Additionally, quercetin and cyanidin had significantly higher antifungal activity than their glycosylated derivatives. Peel extract volatiles treated with glucosidase had antifungal activity. GCMS analysis identified 15 volatiles after glucosidase hydrolysis, seven of them present only in red fruit.These results suggest that the fruit obtains a concealed arsenal of glycosylated flavonoids in its peel when they are hydrolyzed by b-glucosidase that is induced in both fungus and host during infection process, become more toxic to the fungal pathogen, inhibiting decay development.

Induced defense response in red mango fruit against Colletotrichum gloeosporioides

“…Both anthocyanins and flavonoids have pleiotropic effects and are known to be involved in plant protection against pathogens 1 . Flavonoids and anthocyanins play a significant role as antifungal compounds 9 . In the current manuscript, we show that flavonoids and anthocyanins are present in their glycosylated form in the fruit skin and that their amounts decrease 2- to 3-fold as the fungal infection progresses (Fig.…”

“…Flavonols also play a part in the constitutive defense response 1 . In a recent publication, we found a high accumulation of flavonols and anthocyanins, mostly in their glycosylated form, in the skin of red mango fruit; these compounds exhibited direct antifungal activity against fungal pathogens such as Colletotrichum 9 . Interestingly, as the fungi attack, it secretes β -glucosidase, which results in aglycon flavonoids that were more toxic to the fungi 9 .…”

“…Total flavonoid and anthocyanin contents, and 2,2diphenyl-1-picrylhydrazyl (DPPH) and reactive oxygen species (ROS) activity in infected RF and GF Total anthocyanin content in skin extracts of C. gloeosporioides-infected RF and GF at 0-7 dpi was determined by spectrophotometry after organic methanol extraction of the skin followed by absorption measurement at 528 nm 7 . Total flavonoid content in the infected RF and GF skin at 0-7 dpi was extracted and measured using the aluminum chloride colorimetric method 9 ; different concentrations of quercetin were used as a standard for quantification. The absorbance was measured at 415 nm in a UV spectrophotometer, and total flavonoid contents were determined in triplicate.…”

Patterns of Sequence and Expression Diversification Associate Members of the PADRE Gene Family With Response to Fungal Pathogens

“…Response to hypoxia (FDR = 9.45E-3, FDR = 9.29E-27) was overexpressed during infection by S. sclerotiorum whereas genes involved in the cell-cell junction assembly were downregulated ( Figure 6C). The subnetwork grouping genes associated with the biosynthesis of anthocyanin (FDR = 2.7E-4), secondary metabolites with antifungal activity (Kumar Sudheeran et al, 2019), appeared overexpressed during infection. To test further the role played by AtPADRE genes in the topology of the network, we computed the local centrality (or degree) of every gene (Supplementary Figure S2).…”

Integrative Metabolomic and Transcriptomic Analyses Reveal Metabolic Changes and Its Molecular Basis in Rice Mutants of the Strigolactone Pathway

“…The core flavonoids are subjected to multiple modifications, such as hydroxylation, oxidation, methylation, glycosylation, and acylation. Frequently occurring tailoring modifications contribute greatly to the structural as well as functional diversity of flavonoids [9][10][11][12][13] with dozens of flavonoids detected in most plant species, showing significant interspecies and intraspecies diversity [11,[14][15][16][17].…”