Back to Contents

FREE FULL TEXT PDF

1 - AMINOCYLOPROPANE - 1 - CARBOXYLATE (ACC) - DEAMINASE RHIZOBACTERIA EXTENUATES ACC-INDUCED CLASSICAL TRIPLE RESPONSE IN ETIOLATED PEA SEEDLINGS

B. SHAHAROONA, RIFFAT BIBI, MUHAMMAD ARSHAD, ZAHIR AHMED ZAHIR, AND ZIA-UL-HASSAN

Abstract: Ethylene is well thought-out stress hormone because its synthesis is induced by a variety of stresses. 1-Aminocyclopropane-1-carboxylate (ACC) is the immediate precursor of ethylene in higher plants. Some rhizobacteria can hydrolyze ACC into ammonia and α-ketobutyrate because of their ACC-deaminase activity. This study was conducted to investigate the influence of ACC-deaminase rhizobacteria on the ACC-induced classical “triple” response in etiolated pea seedlings. Etiolated pea seedlings were exposed to different concentrations of ACC (0, 2, through 10 mmol L^-1), in 100 ml glass beakers placed in airtight mason jars wrapped in green foil and incubated under dark for seven days. In another study pea seedlings were inoculated with five strains of rhizobacteria which vary in their ACC-deaminase activity. These inoculated pea seedlings were exposed to 10 mmol L^-1 ACC and incubated in the darkness at 25 ± 3 ºC. Results revealed that exogenous application of ACC had a concentration-dependent effect in creating classical “triple” response in etiolated pea seedlings. Inoculation with rhizobacteria decreased the ACC-imposed classical “triple” response in etiolated pea seedlings, as significant increases in seedling length (up to 4.6-folds) and root elongation (up to 3.9-folds) were recorded over uninoculated ACC-stressed control. Stem diameter was significantly decreased (up to 31%) than uninoculated ACC-stressed control in response to inoculation. A significant (P < 0.05) positive correlation (R² = 0.91) was recorded between ACC-deaminase activity and seedling length which implies that ACC-deaminase activity of rhizobacteria was responsible in decreasing the classical “triple” response in etiolated pea seedlings. Our study concludes that the inoculation with rhizobacteria containing ACC-deaminase could be used to decrease ACC which produces due to a variety of biotic and abiotic stresses in plants.

Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad-38040, Pakistan
Corresponding Author: Muhammad Arshad; bio@fsd.comsats.net.pk