Flavan‑3‑ol and favonol analysis in healthy and infected parents and progenies of cocoa leaves (Theobroma cacao L.) with Phytophthora megakarya Bras. and Grif

Flavonoids are phenolic compounds involved in defense mechanisms against black pod disease (BPD). Crossing between Forastero and Trinitario-resistant cocoa genotypes usually produce resistant progenies with high contents of bioactive components. This study aims at analyzing flavan-3-ol and flavonol content in the defense against P. megakarya in T. cacao genotypes for their potential selection as markers of partial resistance to BPD. Assessment of necrosis development and biochemical markers of stress (total polyphenols (TPP), total flavonoids (TF), and condensed tannins (CT)) through spectrophotometric methods of 19 genotypes identified eight hybrids that contained higher amounts (P˂0.05) of bioactive components than the better parent T79/467. The necrosis length revealed to be negatively correlated with metabolite concentrations (P < 0.05). Flavan-3-ols and flavonols were analyzed by normal phase (NP) and reverse phase (RP) HPLC–DAD-ESI (-)-MS/MS. Among the best genotypes, flavan-3-ol monomers (( +)-catechin, (-)-epicatechin), derived procyanidins (especially B2 and four of its isomers, C1, and one pentamer), and flavonols (quercetin, quercetin-3-O-arabinoside, quercetin-3-O-glucoside, quercetin-3-O-rhamnoglucoside, and one isomer) were evidenced both in healthy and infected leaves. Analyzed metabolites increase following infection, but infection does not trigger the synthesis of new compounds. The order of accumulation of biomolecules is as follows: (-)-epicatechin (196%), procyanidin C1 (184%), pentamers (140%), procyanidin B2 (135%), quercetin (80%), quercetin derivatives (57–69%), and ( +)-catechin (57%). Yet their accumulation after infection revealed to be genotype-dependent. This breeding approach is designed to select partial resistant cocoa genotypes against BPD evidenced useful biomarkers in hybrids with high flavonoid content.