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Enzyme phenotypes, specifically esterases (EST) and malate dehydrogenase (MDH), were used to characterise different species of Meloidogyne from Chile. Esterase activity was highly polymorphic and was the most useful in the identification of the different species. Using this enzyme it is possible to characterise and identify M. ethiopica in about 80% of samples on grapevine, kiwi and tomatoes. Another three species, M. javanica, M. hapla and M. arenaria, were identified on tomatoes, kiwi and pomegranate with only one or a few populations. It was possible to detect minor atypical (unidentified) phenotypes, generally in mixed populations with M. ethiopica. Only the profiles N1 and H1 of MDH were detected. N1 was not specific and H1 allowed identification of M. hapla. Contaminated nursery stock has probably resulted in serious infestation by M. ethiopica in vineyards in various localities in Chile. [ABSTRACT FROM AUTHOR]

Aqueous extracts of the tree Quillaja saponaria Molina, containing triterpenoid saponins, polyphenols, salts and sugars, were tested against the most important plant-parasitic nematodes present in Chile: Xiphinema index, X. americanum s.l., Meloidogyne hapla, M. ethiopica, Pratylenchus thornei, Tylenchorhynchus sp., Criconemoides xenoplax and Helicotylenchus sp. Three different products were tested in the laboratory: i) QL 1000® (whole extract containing saponin and non-saponin fractions); ii) QL ULTRA® (saponin fraction); and iii) QL NS® (non-saponin fraction). The results showed that QL 1000® had important nematicidal effects at economically attractive doses (e.g., 100 ppm). When used separately, QL ULTRA® and QL NS® had minimum nematicidal effects. However, the combined use of both products gave similar results to QL 1000®, suggesting a synergy between the saponin and non-saponin fractions. Based on this, QL 1000® was tested in commercial vineyards and table grapes in the Central region of Chile. The use of 30 l ha-1 showed a similar control and fruit yields to synthetic chemical nematicides. [ABSTRACT FROM AUTHOR]

Isoelectrofocusing of superoxide dismutase (SOD) isoforms was carried out on the extracts of 117 nematode populations belonging to the so-called Xiphinema americanum-group. These populations came from the USA (77), Chile (5), Argentina (1), Venezuela (5), Portugal (15), Italy (2), Crete (1), Montenegro (1), Slovakia (4), Hungary (3), Egypt (1) and India (2). A total of 17 bands of enzyme activity were observed in the screening, whilst single enzyme phenotypes showed from two to eight bands. The high degree of SOD polymorphism of this nematode collection was grouped by cluster analysis into seven distinct homogeneous groups characterised by specific combinations of SOD markers. Sub-groups could be discriminated for larger groups. The small Groups 3 and 5 were constituted mostly by populations from USA east coast states (i.e., NY and PA, respectively). The larger Group 1 resulted from the association of populations coming from various and distant North American States. In other large groups, North American populations were associated with South American and European populations. Overall, the data presented here suggest that geographic separation and different hosts do not seem to be the source of genetic diversity for the X. americanum-group. When an adequate number of populations were collected from the same country, the variability expressed by such a sub-sample was comparable to that of the whole nematode collection. For the first time, homogeneous populations of a large collection of X. americanum-group populations were associated by molecular means in order to explore further approaches that may help resolve the recalcitrant taxonomy and phylogeny of this much debated group. [ABSTRACT FROM AUTHOR]