Short-Term UV-B Exposure Induces Changes in Carbohydrate Metabolism and Phenolic compounds in Winter and Summer Lemon Peel

RAPISARDA, VIVIANA; ROSA, MARIANA; PRADO, FERNANDO; INTERDONATO, ROQUE; HILAL, MIRNA

Foz de Iguazu

Congreso; International Congress of Citriculture; 2016

INSTITUTO AGRONÔMICO DO PARANÁ

The UV-B radiation as a postharvest alternative method induces the accumulation of phenolic compounds which could act as defense molecules against pathogens. The aim of this work was analyze both the sucrose metabolism and phenolic compound content in the peel of winter and summer postharvest lemons exposed to artificial UV-B radiation. Yellow mature lemons were irradiated during 2 and 3 min with artificial UV-B in both winter and summer. After standing for 24h samples of albedo and flavedo tissues were cut from irradiated fruits and were used to chemical and enzymatic determinations. In flavedo of summer lemons, higher levels of soluble acid invertase and phenolic compounds were observed when comparing with the flavedo of winter lemons. Cell wall-bound acid invertase activity was higher in winter flavedo than in summer one. Soluble carbohydrates (mainly fructose) and phenolic compounds of the flavedo tissue were increased under UV-B treatment. In albedo, the sucrose synthase involved in the flux of carbon towards the flavedo was increased in UVB-irradiated lemons. Carbohydrate metabolism in both winter and summer lemon peel appears to be different and also is influenced by environmental conditions during fruit growth. The UV-B radiation induces the synthesis of phenolic compounds which can protect lemon fruit against pathogen attack.