Infection and ultraviolet light treatment affect host defense compounds in cashew (Anacardium occidentale) pseudoapple

The effects of various treatments (wounding, infection and ultraviolet-B light) on total phenolics, flavonoids and ascorbic acid contents in cashew pseudoapples that showed reduction in rot with UV-B treatment was investigated. Infection was by wound inoculating fruits with spores of Gilbertella persicaria before or after exposure to UV-B then storing for 72 h. Results show that peels of intact fruits had the lowest amount of total phenolic (TPC) and flavonoid compounds. Wounded fruits subjected to UV treatment had 58.27 and 8.15 mg g^‑1 phenolics and flavonoids respectively. Control fruits had the highest amount of TPC but same quantity of flavonoids with wounded fruits. No significant difference occurred between fruits exposed to UV before or after inoculation. Fruits that were wounded, inoculated and exposed to UV had the highest quantity of flavonoids. Wounding, infection, and exposure to UV all resulted into more phenolic compounds formation although infection elicited the greatest production. Ascorbic acid (AA) was highest in fruits inoculated + UV and lowest in intact fruits. UV-B treatment promoted ascorbic acid formation in the order: UV treatment > wounding > infection. The high amount of TPC in inoculated fruits show they play a role in host-defense while UV may have been more active against the pathogen.