Effects of paclobutrazol on leaf water potential, ethylene production, ACC, ACC-oxidase and polyamines in mango seedlings.
Murti G. S. R., Upreti K. K.
Author Affiliation: Plant Hormones Laboratory, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore 560 089, India.
Journal of Plant Biology 32 : 183-188
Abstract : Effects of soil drenching treatments of paclobutrazol (0, 100, 250 and 500 mg/litre) on morphological characters, leaf water potential, ethylene production, 1-aminocyclopropane-1-carboxylic acid (ACC), ACC-oxidase and polyamines were investigated in the seedlings of polyembryonic mango cv. Bappakai at 30, 60 and 120 days of treatment. Paclobutrazol reduced plant height, production of leaves and stem girth; the effects being pronounced at 500 mg/litre after 120 days. Leaf water potential (?w) was less negative in the paclobutrazol-treated seedlings. There was reduction in ethylene production, ACC content and ACC-oxidase activity but increase in total polyamines, spermidine and spermine in response to paclobutrazol treatments. No definite trends were evident in the putrescine levels. The changes in ethylene production, ACC content, ACC-oxidase activity and spermidine levels were apparent in the seedlings at 120 days and in spermine content at 60 days after paclobutrazol treatment at 500 mg/litre. It is suggested that changes in ethylene biosynthesis and polyamine metabolism in mango seedlings could be the consequence of metabolic alterations brought about by paclobutrazol unrelated to its growth inhibitory response. A role for leaf ?w in the paclobutrazol-induced vigour control is suggested.