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Identification of secondary metabolites associated with protection against mango gall fly infestation and blossom malformation

Augustyn, W. A., Regnier, T., Combrinck, S.
Acta horticulturae 2017 no.1183 pp. 271-278
Fusarium, Mangifera indica, abnormal development, biomarkers, chemometrics, cultivars, fruit yield, galls, gas chromatography-mass spectrometry, insect infestations, insects, leaves, mango malformation disease, mangoes, models, new variety, panicles, parasitism, pests, phenolic compounds, secondary metabolites, shoots, ultra-performance liquid chromatography
Mango gall fly (Procontarinia matteiana) parasitises young leaves of mango. Serious outbreaks can result in reduced fruit yield. Volatile secondary metabolites emitted by the leaves appear to play a role in attraction of the insect to flush leaves. Certain cultivars demonstrate the ability to inhibit the development of the insect, which is characterised by the formation of pseudogalls, rather than true galls. In this study, the metabolic profiles of immature and mature leaves from mango cultivars of varying susceptibility to mango gall fly attack, as well as pseudogall-forming capabilities, were obtained by gas chromatography mass spectrometry (GC-MS). In addition, the phenolic profiles of mature leaf extracts from cultivars with varying degrees of resistance to Procontarinia, as well as to Fusarium infection, were obtained using ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-ToF-MS). Infection of mango panicles and young leaf shoots by Fusarium also contributes to significantly lower fruit yields. This condition is known as blossom malformation. Some mango cultivars are known to be tolerant to blossom malformation, while others are highly susceptible. Chemometric models constructed from GC-MS and UPLC-ToF-MS data revealed a clear distinction between the chemistries of susceptible and resistant cultivars for both pests. The models developed allowed for the identification of biomarkers associated with susceptibility and with resistance. Prediction models constructed from data obtained from the leaves of mango cultivars with varying susceptibilities to the pests were used to identify new cultivars that produce secondary metabolites that could play a role in the protection against gall fly infestation, as well as mango malformation.