New Zealand Journal of Crop and Horticultural Science abstracts
Biocontrol of Phytophthora cactorum in vitro
with Enterobacter aerogenes
D. T. BREWSTER
A. G. SPIERS
D. H. HOPCROFT
The Horticulture and Food Research
Institute of New Zealand
Private Bag 11 030
Palmerston North, New Zealand
Abstract Phytophthora cactorum causes significant
mortality of mature trees in New Zealand pipfruit orchards. Replants of
infected sites often succumb to this pathogen within 3 years.
Enterobacter
aerogenes, strain B8 was reported to control
P. cactorum infection
of apples in nursery soils in British Columbia. This strain was imported to New
Zealand in 1991 and compared with indigenous isolates of
E. aerogenes.
The Canadian isolate differed from New Zealand isolates in utilisation of
tartrate, tolerance of NaCl (5 cf. 7%), and inhibition of
P. cactorum in
vitro. Strain B8 was fungicidal whereas New Zealand isolates were fungistatic.
Electron microscopy of mycelium exposed to strain B8 on agar revealed extensive
disruption of cell membranes, intermixing and aggregation of organelles,
necrosis, vacuolation, breakdown of the cell wall, and hyphal death. Hyphae
exposed to New Zealand isolates of
E. aerogenes exhibited vacuolation of
the outer cytoplasm and degradation of the cell wall and plasmalemma but not
cell degradation and death.
Keywords Enterobacter aerogenes; inhibition;
Phytophthora; biocontrol; ultrastructure
New Zealand Journal of Crop and Horticultural Science, 1997, Vol. 25:
9-18
0114-0671/97/2501-0009 $2.50/0 (c) The Royal Society of New Zealand
1997
PDF file of entire paper: medium quality (3032K); (scanned from paper original: notes about this process)
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