Pak. J. Bot., 45(SI): 487-494, 2013.

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EFFECT OF BACTERIA CONTAINING ACC DEAMINASE ON GROWTH OF WHEAT SEEDLINGS GROWN WITH CHROMIUM CONTAMINATED WATER

IRAM SHAHZADI¹, AZEEM KHALID^1*, SHAHID MAHMOOD¹, MUHAMMAD ARSHAD², TARIQ MAHMOOD¹ AND IRFAN AZIZ³

Abstract: Chromium (Cr) is considered as toxic environmental pollutant and causes harmful effects on growth and development of plants and human health. Usually, high level of ethylene (a plant hormone) is produced in plants in response to any biotic or abiotic stress. Negative effect of Cr-imposed stress on plants may be minimized by using bacteria possessing an enzyme 1-amino-cyclopropane-1- carboxylic acid (ACC)-deaminase. The aim of this study was to investigate the effect of plant growth-promoting bacteria containing ACC-deaminase on wheat under different levels of Cr applied to growth medium. Experiments were conducted under laboratory and lath house conditions. Results of this study demonstrated that inoculation of wheat seeds with two strains of bacteria Pseudomonas fluorescens (Q14) and Bacillus thuringiensis (KAP5) significantly increased the root length (up to 208%), shoot length (up to 67%), root dry weight (up to 140%) and shoot dry weight (up to 71%) respectively as compared to uninoculated control plants. Strain KAP5 possessing both ACC-deaminase as well as phosphate solubilizing activity was found to be the most effective in improving the plant growth compared to uninoculated control in both sand and soil experiments. Inoculation also significantly increased the accumulation of Cr in root and shoots compared to uninoculated control, where the Cr uptake 80.8µg/g dry mass and 69.9µg/g dry mass in root and shoot respectively, was observed. These findings indicated that ACC-deaminase producing bacterial strains could play vital role in improving the plant growth under metal-stress condition and they may enhance bioremediation process in Cr-contaminated environment. Moreover, presence of dual plant growth promoting trait such as ACC-deaminase and phosphate solubilizing activity could have more promising effect on plant growth and Cr removal than the single trait bacterium.

¹Department of Environmental Sciences, PMAS Arid Agriculture University, Rawalpindi 46300, Pakistan

²Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad 38040, Pakistan

³Department of Agronomy, PMAS Arid Agriculture University, Rawalpindi 46300, Pakistan

^*Corresponding author e-mail: azeemuaf@yahoo.com