AAL-Toxin-Deficient Mutants of Alternaria alternata Tomato Pathotype by Restriction Enzyme-Mediated Integration.

ABSTRACT Host-specific toxins are produced by three pathotypes of Alternaria alternata: AM-toxin, which affects apple; AK-toxin, which affects Japanese pear; and AAL-toxin, which affects tomato. Each toxin has a role in pathogenesis. To facilitate molecular genetic analysis of toxin production, isolation of toxin-deficient mutants utilizing ectopic integration of plasmid DNA has been attempted.

Purification and Biological Characterization of Host-Specific SV-Toxins from Stemphylium vesicarium Causing Brown Spot of European Pear.

ABSTRACT Culture filtrates of a pathogenic isolate (IT37) of Stemphylium vesicarium, causing brown spot of European pear, induced veinal necrosis only on pear leaves susceptible to the pathogen. Two host-specific toxins, SV-toxins I and II, were purified from culture filtrates of IT37 by successively using Amberlite XAD-2 resin adsorption, cellulose thin-layer chromatography, and high-performance liquid chromatography under three different sets of conditions. Susceptible cultivars showed veinal necrosis at a SV-toxin I concentration of 0.

(+)-catechin acts as an infection-inhibiting factor in strawberry leaf.

ABSTRACT An infection-inhibiting factor (IIF) was isolated from strawberry leaves and identified as (+)-catechin. This compound inhibited the formation of infection hyphae from appressoria of Alternaria alternata, but allowed both spore germination and appressorial formation. It is a normal component of strawberry leaves, but further accumulates as the major IIF in response to inoculation with nonpathogenic spores of A.

A Polymerase Chain Reaction-Based Method to Specifically Detect Alternaria alternata Apple Pathotype (A. mali), the Causal Agent of Alternaria Blotch of Apple.

ABSTRACT Alternaria alternata apple pathotype (previously A. mali) causes Alternaria blotch on susceptible apple cultivars through the production of a host-specific toxin, AM-toxin. Identification of some Alternaria species, especially those that produce host-specific toxins, has been extremely difficult due to a high level of variability which extends even to nonpathogenic isolates.