Antifungal proteins and other mechanisms in the control of sorghum stalk rot and grain mold.

Research on antifungal proteins and other mechanisms that provide the biochemical basis for host-plant resistance to stalk rot and grain molds is reviewed in this paper. Stalk rot caused by Fusarium species leads to substantial yield loss due to poor grain filling and/or lodging. A transgenic sorghum expressing high levels of chitinase exhibited less stalk rot development when exposed to conidia of F. thapsinum. Grain mold of sorghum is associated with warm humid environments and results from colonization by several fungi (F. thapsinum, Curvularia lunata, and Alternaria alternata) of the developing caryopsis. The roles of several biochemical mechanisms (tannins, phenolic compounds, red pericarp, proteins, hard endosperm, and antifungal proteins) on grain mold resistance are discussed. Resistance mechanisms related to these compounds appear to be additive, and pyramiding of genes is a feasible approach to limit grain deterioration. Several experimental approaches are proposed to extend current findings.

Activity of antifungal proteins against mold in sorghum caryopses in the field.

Sorghums were stressed with pathogenic fungi and sprinkling to determine relationships between changes in chitinase and sormatin in caryopses and grain mold resistance. Panicles of 10 cultivars differing in mold resistance and accumulation of antifungal proteins (AFPs) were inoculated at anthesis with Fusarium moniliforme and Curvularia lunata spores. Panicles were sampled at 30 and 50 days after anthesis, and caryopses were evaluated for chitinase and sormatin using western blots. Sprinkling panicles (to mimic rainfall) decreased sormatin and chitinase in most cultivars. Inoculation decreased AFPs in susceptible cultivars, but resistant cultivars maintained or increased AFPs in caryopses. Grain mold resistance corresponded to induction of AFP synthesis in response to sprinkling, fungal stress, and/or adverse field conditions. Sormatin and chitinase appear to be an active part of the defense mechanism of the caryopsis against grain mold.

Amaranthus and buckwheat protein concentrate effects on an emulsion-type meat product.

The utilization of Amaranthus (five genotypes) and buckwheat protein concentrates in an emulsion-type meat product comprising beef lean, pork fat, salt and water was studied. 15% of the beef protein was replaced with the protein concentrates and the resulting meat emulsions were evaluated by thermorheology and thermal analysis. The cooking loss and physical properties of the meat gel were determined. The use of Amaranthus and buckwheat protein concentrates considerably affected both the emulsion and the cooked meat gel properties. The most favorable outcome was obtained with the buckwheat protein, which had similar effects to soy proteins. The Amaranthus protein concentrates generally did not give favorable results, although that derived from genotype K112 showed some positive effects. Correlation analysis showed that most of the observed variation in meat product properties could be explained by the emulsifying activity of the protein additive used.