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ISSN : 2456-8643

Title:
VARIATION IN THE PHENOLIC COMPOSITION OF MANGO FRUIT PEEL FOLLOWING INFECTION BY (Colletotrichum gloeosporioides)

Authors:
K.O.L.C Karunanayake,Sri Lanka

Abstract:
Mango fruit at the ripe stage is susceptible to infection by Colletotrichum gloeosporioides causing Anthracnose disease. The pathogen remains quiescent in unripe fruit due to an elaborate arsenal of pre-formed defences. However, induced defences of mango fruit have been reported to contribute to the restriction of the pathogen during initial stages of infection in unripe fruit. Rapid localized generation of superoxides and hydrogen peroxide as an early defence response and increases in phenylalanine ammonialyase and chitinases have been reported. This paper reports the changes in phenol composition in fruit peel following infection by C. gloeosporioides. Conidia were seen to germinate and form appressoria within 24 hours of inoculation. Browning of cell walls was seen in cells in immediate contact with the penetration peg. Histochemical studies proved the accumulation of phenols and tannins at sites of attempted penetration by the pathogen. Quantification of phenols in the fruit peel tissues showed the total soluble phenol content in the mango fruit peel to be higher in peel of inoculated fruit compared to the peel of control fruit, however, the increase was not significant. The cell wall bound phenols in inoculated fruit peel tissue was significantly higher, when compared with the control. It can be concluded that, in addition to the elaborate preformed defences present in mango fruit peel, induced defences are present in the mango fruit peel. The induction of phenols at sites of attempted penetration possibly contribute towards restricting and delaying the pathogen from entering the mature, yet unripe fruit and causing disease.

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