SHORT-TERM UV-B EXPOSURE INDUCES CHANGES IN CARBOHYDRATE METABOLISM AND PHENOLIC COMPOUNDS IN WINTER AND SUMMER LEMON PEEL

INTERDONATO, R.; ROSA, M.; RAPISARDA, V. A.; HILAL, M.; PRADO, F. E.

Congreso; International Citrus Congress 2016; 2016

The UV-B radiation as a postharvest alternative methodinduces the accumulation of phenolic compounds whichcould act as defense molecules against pathogens. The aimof this work was analyze both the sucrose metabolism andphenolic compound content in the peel of winter and summerpostharvest lemons exposed to artificial UV-B radiation.Yellow mature lemons were irradiated during 2 and3 min with artificial UV-B in both winter and summer. Afterstanding for 24h samples of albedo and flavedo tissues werecut from irradiated fruits and were used to chemical andenzymatic determinations. In flavedo of summer lemons,higher levels of soluble acid invertase and phenolic compoundswere observed when comparing with the flavedo ofwinter lemons. Cell wall-bound acid invertase activity washigher in winter flavedo than in summer one. Soluble carbohydrates(mainly fructose) and phenolic compounds ofthe flavedo tissue were increased under UV-B treatment. Inalbedo, the sucrose synthase involved in the flux of carbontowards the flavedo was increased in UVB-irradiated lemons.Carbohydrate metabolism in both winter and summerlemon peel appears to be different and also is influencedby environmental conditions during fruit growth. The UV-Bradiation induces the synthesis of phenolic compoundswhich can protect lemon fruit against pathogen attack.