Pseudomonads isolated from within fruit bodies of Tuber borchii are capable of producing biological control or phytostimulatory compounds in pure culture
S. Bedini et al., Pseudomonads isolated from within fruit bodies of Tuber borchii are capable of producing biological control or phytostimulatory compounds in pure culture, SYMBIOSIS, 26(3), 1999, pp. 223-236
From the core of surface-sterilized sporocarps of Tuber borchii collected i
n Spring 1997, 600 bacterial strains were isolated, among which were about
300 pseudomonads. Counts revealed a consistent presence of Pseudomonas spp.
, at 10(5)-10(8) cfu per gram of dry weight. Identification showed the isol
ates mainly representing species of Pseudomonas fluorescens, P, corrugata a
nd P. tolaasii. Using a monoclonal antibody against indole-3-acetic acid (I
AA) all isolates studied were found to be phytohormone-producing ex-planta.
Some isolates were examined and found to be producers of biocontrol substa
nces (2,4 diacetylphloroglucinol, HCN, proteases and fluorescent siderophor
es) and active in carboxy-methyl cellulase and collagenase activities. Biol
ogical assays revealed weak biocontrol activity explanta against Botrytis c
inerea, Cryphonectria parasitica, Diplodia mutila, Phytophthora cactorum an
d Phytophthora cinnamomi, whereas Fusarium oxysporum f.sp. dianthii was una
ffected by the strains tested.