Resumo

ARRIETA-GUEVARA, MAIRA ANDREA; HIGUERA-MANCIPE, BLANCA LIGIA  e  MARTINEZ-PERALTA, SIXTA TULIA. Induction of phenylalanine ammonia lyase and variation in phenolic compounds content in Lulo fruits (Solanum quitoense Lam) infected by Colletotrichum acutatum). Acta biol.Colomb. [online]. 2010, vol.15, n.1, pp.129-144. ISSN 0120-548X.

Phenylalanine ammonia lyase (PAL) activity induction was evaluated in lulo fruits to determine the role of this enzyme in biochemical responses towards the pathogen Colletotrichum acutatum. We studied the experimental conditions to obtain the enzyme, using lulo peel, and found that the best conditions for extraction were buffer of boric acid-sodium borate 0.1M pH 8.8, 1% SDS, 3% PVPP and, for measuring the enzymatic activity: L- phenylalanine 5mM, pH 8.0, 20°C , 30 ΜL of extract and incubation during 45 min. Then, we performed an in vivo assay using lulo fruits in three maturity stages, which were inoculated either with the fungus or sterile water. Enzymatic induction was studied at five post-inoculation times, and it was found that there is a differential response as a consequence of the presence of the pathogen and the maturity stage. In semi-mature lulos, a bigger increase in PAL was obtained among 12-48 hpi which is related to a higher content of phenolic compounds and to the latest development in the characteristic symptoms of anthracnose. These results allow postulating, in a preliminary way, a possible positive relationship between inductions of PAL, phenolics and responses of tolerance to C. acutatum. For green and mature lulos we observed as well, an increase of PAL activity but only at 12 and 24 hpi which showed relation with an increase in the total phenolic content. However, for these stages the phenolics were significantly lower at higher times.

Palavras-chave : Lulo; phenylalanine ammonia lyase; anthracnose; vegetal defense; enzymes.

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