Determination of 1-aminocycopropane-1-carboxylic acid (ACC) to assess the effects of ACC deaminase-containing bacteria on roots of canola seedlings

Previously, it was proposed that plant growth-promoting bacteria that posse ss the enzyme, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, can r educe the amount of ethylene produced by a plant and thereby promote root e longation. To test this model, canola seeds were imbibed in the presence of the chemical ethylene inhibitor, 2-aminoethoxyvinyl glycine (AVG), various strains of plant growth-promoting bacteria, and a psychrophilic bacterium containing an ACC deaminase gene on a broad host range plasmid. The extent of root elongation and levels of ACC, the immediate precursor of ethylene, were measured in the canola seedling roots. A modification of the Waters Ac cQ.Tag Amino Acid Analysis Method(TM) was used to quantify ACC in the root extracts. It was found that, in the presence of the ethylene inhibitor, AVG , or any one of several ACC deaminase-containing strains of bacteria, the g rowth of canola seedling roots was enhanced and the ACC levels in these roo ts were lowered.