Possible interactions of polyamines and ethylene during ripening of guava (psidium guajava l.) fruits
2008
MONDAL, K. | SINGH, A.P. | SAXENA, N. | MALHOTRA, S.P. | DHAWAN, K. | Singh, R.
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. Guava (Psidium guajava L.) is an important fruit crop of India and has become very popular because it is rich in nutrient value, moderately priced and has good flavor. Guava is referred to as Poor's apple in many parts of India. Guava has a short shelf life and is most vulnerable to bruising and physical damage, which account for its greatest economical loss. This study indicated the possible interaction of polyamines and ethylene. These results showed that cv L-49 has a longer keeping quality and a lower amount of ethylene and a higher value of polyamines. In light of these findings, one commercial possibility can be exploited that the exogenous application of polyamines, to low concentrations, can be applied to enhance the shelf life of fruits.
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