Fulfilling Koch's postulates confirms the monopartite nature of tomato leaf deformation virus: a begomovirus native to the New World.

The monopartite nature of the begomovirus tomato leaf deformation virus (ToLDeV) reported in Peru is demonstrated here. The DNA molecule cloned from an infected plant was shown to be fully infectious in tomatoes inducing leaf curling and stunted growth similar to that observed in field-infected plants. The viral DNA was reisolated from systemically infected tissues of inoculated plants, thus fulfilling Koch's postulates. ToLDeV was demonstrated, therefore, as the causal agent of the disease syndrome widespread in tomato crops in Peru. This virus was shown to be present throughout the major tomato-growing regions of this country, both in tomatoes and wild plants. Analyses of the sequences of 51 ToLDeV isolates revealed a significant genetic diversity with three major genetic types co-circulating in the population. A geographical segregation was observed which should be taken into account for virus control. Constraints to genetic divergence found for the C4 gene of ToLDeV isolates suggest a relevant function for this protein. The results obtained confirm ToLDeV as a monopartite begomovirus native to the New World, which is a significant finding for this region.

Functional properties of proteins from Lima bean (Phaseolus lunatus L.) seeds.

Functional properties were identified for the total globulin (TG), 7S and 11S fractions of Lima bean (Phaseolus lunatus L.) seeds. The 11S component accounted for 58.3% of TGs and the 7S for 41.7%. Solubility was higher in the 7S fraction, especially at alkaline pHs. Water-holding capacity was similar (3 g water/g sample) in both globulin fractions. Oil-holding capacity was higher in the 11S fraction, which also exhibited better foaming capacity and foam stability than the 7S and TG fractions at alkaline pHs. The TG and 7S fractions exhibited low emulsifying capacity and emulsion stability at different pHs (5, 7 and 9), but the 11S fraction had relatively higher values. In suspension at low concentrations, all fractions exhibited shear-thinning (pseudoplastic) behavior. The studied Lima bean globulin fractions exhibit functional properties which make them potentially apt for use in some industrial food systems.

Composition and functional properties of Lupinus campestris protein isolates.

Protein isolates from L. campestris and soybean seeds were prepared using isoelectric precipitation (PI) and micellization (MI) procedures. The amount of protein recovered was considerably higher with the isoelectric precipitation than with the micellization procedure (60% and 30%, respectively). Protein contents were higher than 90% in protein isolates. Antinutritional factors content (alkaloids, lectins, and tannins) were reduced to innocuous levels after protein isolate preparation. Minimum protein solubility for the precipitated lupin protein isolate (LPI) was at pH 4.0, and between pH 4 and 6 for the micellized lupin protein isolate (LMI), increasing at both extremes of the pH scale. Water absorption for the LMI was 1.3 ml/g of protein and its oil absorption 2.2 ml/g of protein. The LPI had 1.7 ml/g of protein in both water and oil absorption. Foaming capacity and stability was pH-dependent. Foaming capacity was higher at pH 2 and lower near the protein isoelectric points. Minimum protein concentration for gelation in LMI was 8% w/v at pH 4, while for LPI was 6% at pH 4 and 6. Amino acid composition in L. campestris flour and protein isolates was high in lysine and low in methionine. Most of the essential amino acids in lupin protein isolates were at acceptable levels compared to a reference pattern for infants and adults. The electrophoretic pattern of both protein isolates showed three bands with different mobilities, suggesting that the protein fractions belong to alpha-conglutin (11S-like protein), beta-conglutin (7S-like protein) and gamma-conglutin. It is proven that some of the functional properties of L. campestris protein isolates are similar to those soybean protein isolates recovered under equal conditions.