Possible interactions of polyamines and ethylene during ripening of guava (psidium guajava 1.) fruits

Abstract

The rate of ethylene evolution, 1-amino cyclopropane 1-carboxlylic acid (ACC) content, ACC oxidase activity and free polyamines were monitored during fruit ripening of two guava cultivars (Psidium guajava) i.e., L-49 (shelf life 7-8 days) and Hisar Safeda (shelf life 3-4 days). Ethylene evolution and ACC oxidase activity were substantially high at turning (T) stage and low at the later stages of fruit ripening, indicating the climacteric nature of the fruit. Contrary to this, ACC content increased progressively throughout ripening, suggesting that ACC oxidase was the rate-limiting step in the biosynthetic pathway of ethylene. The level of putrescine, spermidine and spermine was minimum at the onset of climacteric, suggesting a competition for a common intermediate, S-adenosylmethionine, which, at T stage, is channeled toward ethylene and at later stages, toward polyamines. Less ethylene and higher level of polyamines in L-49 than in Hisar Safeda may be one of the reasons for the prolonged shelf life of L-49.