Polyphenol oxidase activity in mango (Mangifera indica L.) in relation to flowering behaviour and the malformation incidence.
Sharma R. R., Singh C. N., Goswami A. M.
Author Affiliation: Division of Fruits and Horticultural Technology, Indian Agricultural Research Institute, New Delhi - 110012, India.
Fruits (Paris) 56 : 219-224
Abstract : Biennial bearing and malformation are two present problems of mango which are threatening the very existence of a global mango industry in India. Many factors are closely associated with these problems but, presently, those really responsible are not known exactly. Polyphenol oxidase [catechol oxidase] (PPO) plays a vital roles in higher plants and, hence, its activity was measured in swollen buds at panicle initiation in regular and biennial bearing mango cultivars to establish a relation between the PPO activity and the flowering behaviour or the malformation incidence. Six regular (Sensation, Eldon, Tommy, Atkins, Amrapali, Neelum and Bangalora) and six biennial bearing cultivars (Langra, Chausa, Edward, St. Alexandrina, Extrema and Bombay Green) were studied. PPO activity was measured in fully swollen buds by preparing a crude enzyme extract at 4°C. Catecholase activity was measured by using 4-methyl catechol (4-MC) as the substrate, while 4-methyl phenol (p-cresol) was used for cresolase [monophenol monooxygenase]. Both catecholase and cresolase activities were higher in the swollen buds in the year 2000 than in 1999. Regular bearers exhibited low PPO activity and showed the higher incidence of malformation compared to the biennial bearing cultivars. Whatever their type of production, cultivars exhibited significant variations in PPO activities and malformation incidence. A strong negative correlation between PPO activity and number of panicles, and PPO activity was inversely related to both flowering and malformation incidence in mango.