Ana Julia Colmenares

THE PUTATIVE ROLE OF BOTRYDIAL AND RELATED METABOLITES IN THE INFECTION MECHANISM OF Botrytis cinerea

Phytotoxic assays, performed both in vitro and in vivo on leaves of Phaseolus vulgaris, with metabolites excreted by the fungus B. cinerea are evaluated. Exogenous application of the phytotoxin botrydial has been found to produce severe chlorosis and cell collapse and facilitated fungal penetration and colonization of plant tissue. The results also show a light-dependent action mechanism for the phytotoxin and seem to indicate that botrydial is a non-host-specific toxin involved in fungal infection of B. cinerea.

Botrydial is produced in plant tissues infected by Botrytis cinerea.

The fungal metabolite botrydial was detected for the first time in ripe fruits of sweet pepper (Capsicum annuum) wound-inoculated with conidial suspensions of Botrytis cinerea and also in leaves of Phaseolus vulgaris and Arabidopsis thaliana inoculated without wounding. This phytotoxin was produced in soft rot regions of the infection. In C. annuum, the most aggressive isolate produced the highest botrydial concentrations in planta. The levels of botrydial produced by this isolate did not correlate with the reported relative susceptibilities of four P. vulgaris genotypes. The results suggest that botrydial is a pathogenicity factor for this fungus, but not a primary determinant of pathogenicity.

Some key metabolic intermediates in the biosynthesis of botrydial and related compounds

Abstract The isolation of three key intermediates from a culture of Botrytis cinerea sheds further light on the biosynthetic pathway to botrydial ( 2 ), and clarifies and establishes the stereochemistry of the oxidative steps which affect the probotryane skeleton to lead to the dialdehyde ( 2 ). The structures of these three new metabolites have been determined by means of extensive spectroscopic methods.

Studies on the biosynthesis of secobotryane skeleton

Abstract The labelling and coupling patterns of secobotrytrienediol, biosynthesised from [1-13C] and [1,2-13C2]-acetate by the fungus Botrytis cinerea, have been used to define the mode of formation and the biogenetic origin of secobotrytrienediol. [10-2H]-Botrydiol was not incorporated into the secobotryane skeleton. In addition, this feeding experiment led to the isolation of three new unlabelled derivatives possessing a secobotryane skeleton, secobotrydiene-3,10,15-triol, secobotrydiene-3,4,10,15-tetraol, and secobotrytriene-10,12,15-triol.

Safety and quality assessment of smallholder farmers' maize in the western highlands of Guatemala

Maize ( Zea mays) is a staple in many developing countries but is known to be prone to pest (insects, birds, and rodents) and fungal infestation. In Guatemala, mycotoxin contamination of cultivated products may occur owing to such factors as environmental conditions and the use of traditional agriculture operations. To assess the current maize conditions in Guatemala, a small-scale study was performed. Mold and insect counts and mycotoxin (aflatoxin and fumonisin) concentrations were determined on 25 farms in two townships (Chiantla and Todos Santos) of the Huehuetenango Department. Total fungal counts were 3.6 to 6.83 log CFU/g with no significant differences ( P > 0.05) across farms at different altitudes. Farms where maize was not produced but was purchased were at higher risk of fumonisin contamination, whereas local producers were mostly affected by aflatoxins. Aflatoxin was present in maize from 100% of farms at 1.0 to 85.3 ppb, and fumonisin was detected on 52% of farms at 0.4 to 31.0 ppm. Average mycotoxin consumption amounts were above the recommended maximum intake for aflatoxin in both produced and purchased maize and above the provisional maximum tolerable daily intake for fumonisin in purchased maize. Estimated daily intake was 0.01 to 0.85 μg/kg of body weight per day for aflatoxin and 2.9 to 310.0 μg/kg of body weight per day for fumonisin. An entomological analysis revealed overall 32% prevalence of Ephestia kuehniella (flour moth), 16% prevalence of Sitophilus zeamais (maize weevil), and 8% prevalence of Tribolium sp. (flour beetle) on the analyzed farms. This study highlighted poor agricultural practices used in the highlands of Guatemala. Current practices should be revised for the production of maize that is safe for consumption by the population in this region.