Bacterial black spot in mango (Mangifera indica L.) fruits. Ascorbic acid and the hypersensitive reaction as a means of resistance.
Lelyveld L. J. van
Author Affiliation: Citrus and Subtropical Fruit Research Institute, Nelspruit, South Africa.
Agroplantae 7 : 45-50
Abstract : The development of the symptoms of bacterial black spot (Erwinia mangiferae), a darkening and cracking of the fruit surface, is apparently a typical hypersensitive reaction as it results in necrosis. In studies on the fruit of the mango cvs Sensation (late maturing and relatively resistant), and Haden and Kent (early and susceptible) the enzymic oxidation of ascorbic acid was increased by infection in all 3 cvs. In addition there was a natural fall in the ascorbic acid content as the fruit matured. The highest content, together with the lowest polyphenol oxidase activity, was observed in Sensation fruit. Fruit (of any cv.) containing over 40 mg ascorbic acid/100 g fruit tissue may be more resistant to the disease as expressed by lesion formation.