Abstract

CAICEDO, Obradith; HIGUERA, Blanca L  and  MARTINEZ, Sixta. INDUCTION OF PEROXIDASE AND TOTAL PHENOLS AS A RESPONSE OF LULO (Solanum quitoense L.) FRUIT TO PATHOGEN CAUSING ANTHRACNOSE. Rev.Colomb.Quim. [online]. 2009, vol.38, n.1, pp.25-42. ISSN 0120-2804.

The induction of peroxidase in lulo fruits was evaluated in order to determine its participation in the biochemical responses towards the pathogen Colletotrichum acutatum, which causes the antrachnosis disease. For extraction and activity determination, these conditions were established as the best: buffer phosphates 100 mM pH 7, 1% SDS y 1 % PVPP; substrate guaiacol 15 mM, hydrogen peroxide 10 mM, pH 6,5, 55 °C and 30 µL of the extract. An in vivo test was developed using unripe, semi-ripe and ripe fruits, inoculated with the fungus or sterile water. The peroxidase activity was measured at different hours starting from the inoculation, finding a time differential response caused by the pathogen presence and according to the maturity state of fruits; in unripe lulo fruits inoculated with the fungus, an increase of the activity was observed after 6 and 144 hours. In semi-ripe fruits no considerable effect was seen, while in ripe fruits the increase of the activity was found practically at all times. The results of the measured total phenol content, showed accumulation at 96 and 144 hours as a result of the pathogen presence in unripe and ripe fruits, while for semi-ripe fruits, in which the antrachnosis symptoms were noticed faster and more severely, no phenol increase was found at any time. The less evident changes seen in peroxidase and phenol content, using severely affected fruits by the disease, suggest an inverse relationship between these parameters and the development of the antrachnosis.

Keywords : lulo; Colletotrichum acutatum; peroxidase; phenolics; Solanum quitoense; plant defence.

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