Bakshi, S., Sztejnberg, A., and Yarden, O. 2001. Isolation and characterization
of a cold-tolerant strain of Fusarium proliferatum, a biocontrol
agent of grape downy mildew. Phytopathology 91:1062-1068.
A cold-tolerant strain of the mycoparasite Fusarium proliferatum was
isolated following UV mutagenesis of the G6 strain, which is a biocontrol
agent of grape downy mildew. The isolated strain (designated 1505)
exhibited radial growth two to threefold that of the parent strain when
grown at 13°C, which is generally suboptimal for growth of Fusarium
spp., but desirable for its host, Plasmopara viticola. This rapid growth
was correlated with improved biological control of P. viticola, determined
by a detached-leaf assay. Even though radial growth of strain 1505
at higher temperatures was slower than that of G6 and the strain failed to
conidiate, there was no reduction in biocontrol efficacy. Significantly
higher levels of extracellular β-glucosidase and endo-1,4-β-glucanase
activity were measured in the culture filtrate of strain 1505 relative to
that of strain G6. A DNA-mediated transformation procedure that included
the introduction of antibiotic resistance and a GUS reporter gene
system was adapted for F. proliferatum. Using the GUS-engineered
strains, we demonstrated that both G6 and 1505 exhibit the characteristic
coiling and penetration of host structures.