BIOCONTROL STRAIN OF BACILLUS-SUBTILIS AF-1 RAPIDLY INDUCES LIPOXYGENASE IN GROUNDNUT (ARACHIS-HYPOGAEA L.) COMPARED TO CROWN ROT PATHOGEN ASPERGILLUS-NIGER

Metabolic products of polyunsaturated fatty acids have been variously implicated in control of microbial pathogens. Induced resistance has b een shown as one of the mechanisms of biological control by plant grow th promoting rhizobacteria (PGPR). This paper reports a significant li poxygenase (LOX) activity in groundnut seedlings with production of 13 -hydroperoxyoctadecadienoic acid (13-HPODE) and 13-hydroperoxyoctadeca trienoic acid (13-HPOTrE) as major products with linoleic acid (LA) an d alpha-linolenic acid (ALA), respectively. Both the hydroperoxides ar e inhibitory to the growth of Aspergillus niger as measured in micro t iter plates. Ours is the first report on induction of LOX activities i n groundnut on treatment with a PGPR strain Bacillus subtilis AF 1, an d with crown-rot pathogen, A. niger. Treatment with B. subtilis AF 1 e nhanced LOX levels in groundnut similarly but earlier to A. niger-trea tment. This induction of LOX during activation of growth and pathogen infection was discussed in light of the reported involvement of LOX bo th in growth and development as well as in plant-pathogen interaction, particularly induced disease resistance.