Screening of fluorescent pseudomonads based on production of siderophore and induction of plant ethylene production for induction of systemic resistance against wheat bacterial leaf streak

In this study effect of systemic resistance inducing fluorescent pseudomonads on wheat bacterial leaf streak was investigated. According to the importance of produced siderophore by this kind of bacteria in the induction of systemic resistance, CAS agar medium was used for screening of the isolates with the highest potential for siderophore production. From the 200 isolates that isolated from North West part of Iran, 37 could produce a large amount of siderophore and the diameter of hallo zones produced by these isolates on CAS medium agar was more than 15 mm. Ethylene production bioassay was used for screening the isolates with the potential for induction of systemic resistance in wheat. Among these isolates, only four increased the plant reaction potential against XTC and concentration of ethylene produced by leaf pieces of plants treated by these isolates was more than 2 pmol/ml air. The effect of selected isolates on bacterial leaf streak of wheat in growth chamber was investigated and it was found that only 58A can significantly decrease this disease. Investigation of the enzymatic changes of plant treated by this isolate during pathogenicity process showed that the presence of this bacterium on the wheat roots doesn’t have any effect on peroxidase (PO) and phenylalanine ammonia lyase (PAL) activity in foliage, but after inoculation of the pathogen, the activity of both of them increased.