Molecular and morphometric identification of plant parasitic nematodes

During a nematode survey in vineyards of the Veneto region (Italy), several soil samples were collected. On morphological and morphometric studies, a population from Conegliano Veneto was preliminarily identified as X. rivesi Dalmasso 1969. To support the morphological diagnosis, a molecular characterization of X. rivesi from Italy using the D2-D3 expansion segments of the 28S rDNA and the ITS containing region was undertaken. PCR-RFLP analyses were also performed to determine species-specific patterns for the Italian population of the nematode. Neighbor-Joining, Minimum Evolution and Maximum Parsimony analyses were used to reconstruct phylogenetic relationships within X. rivesi and other Xiphinema species

Evaluation of nematicidal properties of saponins from Medicago spp

The nematicidal activity of saponins from Medicago arborea (tops), M. arabica (tops and roots) and M. sativa (tops and roots) against the plant-parasitic nematode Xiphinema index was investigated. Nematicidal activity of related prosapogenins and sapogenins on X. index is also described. Saponins from Medicago spp. at different concentrations were all nematicidal, those from M. arborea tops being the less effective. In general, saponins induced 100% mortality at 500 mu g ml(-1) between 8 and 48 h, while prosapogenins resulted in toxicity starting at 125 mu g ml(-1). Differences in the effects on X. index induced by prosapogenins and sapogenins were less pronounced, although prosapogenins displayed a larger range of activity. Assays with purified sapogenins demonstrated the relationship of the observed nematicidal activity of M. sativa and M. arborea to the content of the main aglycones (medicagenic acid and hederagenin, respectively) in the saponin extracts. Hederagenin displayed the highest bioactivity, giving 38% mortality after 1 h at 125 mu g ml(-1)