Integrated Nematode Management in a World in Transition: Constraints, Policy, Processes, and Technologies for the Future.

Plant-parasitic nematodes are one of the most insidious pests limiting agricultural production, parasitizing mostly belowground and occasionally aboveground plant parts. They are an important and underestimated component of the estimated 30% yield loss inflicted on crops globally by biotic constraints. Nematode damage is intensified by interactions with biotic and abiotic factors constraints: soilborne pathogens, soil fertility degradation, reduced soil biodiversity, climate variability, and policies influencing the development of improved management options.

DAMAGE RESEARCH WITH P. PENETRANS IN ASPARAGUS PLANTS.

During cultivation of asparagus plants growth can be inhibited and yield can be reduced by plant-parasitic nematodes. Plant raising companies assume that the root lesion nematode (Pratylenchus penetrans) can cause severe yield loss in asparagus plants. However quantitative information about yield reduction in relation to the degree of infestation of this nematode species in the field is lacking.

Optimization of metam sodium application by rotary spading injection.

In The Netherlands the only chemical alternative for methyl bromide permitted is an application of metam-sodium (MS) with the active ingredient methyl isothiocyanate (MIT). After introduction of a new application method with 'rotary spading injection' legislation restricted the application of MS in 1993 to once in four years and since 2001 once in five years. Efficacy after injection of metam sodium at 10 cm depth and rotary spading a 25 cm soil layer was much better than with shank injection at 19 cm depth with a poor efficacy in the top soil layer.

Transmission of tobacco rattle virus (TRV) via seed potatoes.

Susceptibility of potato varieties for tobacco rattle virus (TRV) and sensitivity for spraing in potato tubers both depend on the interaction between cultivar and virus strain. Of the six potato cultivars investigated in this research, cultivar Santana was the most susceptible to TRV, the cultivars Roxy and Saturna were the least susceptible. In general, potato cultivars were most susceptible to the virus type transmitted by P.

Soil treatment with hot air (Cultivit) as alternative to methyl bromide.

A new development in physical soil treatment is the application of hot air. Hot air treatment is based on blowing extremely hot air into rotavating humid soil. The method has been developed and applied commercially in Israel for the last few years.

Comparison of extraction techniques and augers of different size.

Because of differences in winter survival of Pratylenchus penetrans after different host plants, concern arose about traditional extraction and soil sampling techniques. Possible bottlenecks are a too short incubation period of the root material for the time of year, or an auger size to small to pick up tough, fresh, root material. Two experiments were carried out to compare different auger sizes and variations on the standard Oostenbrink elutriation technique with additional filter-incubation of the organic material left on the top sieve (180 microns) of the elutriator.

Host suitability of arable and vegetable crops for Pratylenchus penetrans.

A method was developed to test host suitability for the rootlesion nematode, P. penetrans in pot-experiments. Quarts-sand with transplanted seedlings was inoculated with a suspension of P.

[Doppler ultrasound studies in placental insufficiency as an indication of the effectiveness of hemodilution therapy].

Early diagnosis of intrauterine growth retardation is important to ensure optimal obstetric monitoring. Current methods of diagnosing and assessing the growth retardation include clinical evaluation, various ultrasonic parameters and Doppler ultrasound. In this study Dopplersonographic measurements of the umbilical artery, fetal aorta and the middle cerebral artery were performed on 19 patients having been diagnosed with a placental insufficiency and maternal haemoconcentration.

Production of active Bacillus licheniformis alpha-amylase in tobacco and its application in starch liquefaction.

As a first example of the feasibility of producing industrial bulk enzymes in plants, we have expressed Bacillus licheniformis alpha-amylase in transgenic tobacco, and applied the seeds directly in starch liquification. The enzyme was properly secreted into the intercellular space, and maximum expression levels of about 0.3% of total soluble protein were obtained.

The role of bacterial attachment in the transformation of cell-wall-regenerating tobacco protoplasts by Agrobacterium tumefaciens.

The presence of a newly formed primary cell wall was shown to be required for attachment and subsequent transformation of tobacco leaf protoplasts by Agrobacterium tumefaciens in cocultivation experiments. In these experiments both protoplasts at different stages after their isolation and cell-wall inhibitors were used. The specificity of Agrobacterium attachment was shown by using other kinds of bacteria that did not attach.

A simple method for the identification of aminoglycoside-modifying enzymes.

In order to study the correlation between the presence of aminoglycoside-modifying enzymes in bacteria and the susceptibility of these bacteria to aminoglycosides, 133 resistant strains were collected, representing the most frequently occurring modifying enzymes in clinical isolates today. Enzymes in these resistant strains were identified by the determination of substrate profiles for eight different aminoglycosides in vitro. Thirteen different enzymes or combinations of enzymes appeared to be present in this collection, whereas in seven cases the resistance appeared to be non-enzyme-mediated.

Relation between aminoglycoside 2"-O-nucleotidyltransferase activity and aminoglycoside resistance.

The relationship between plasmid-coded aminoglycoside 2"-O-nucleotidyltransferase [ANT(2")] activity and the minimum inhibitory concentration for aminoglycosides was studied. ANT(2") was very unstable, and therefore, procedures for handling this enzyme were optimized. Escherichia coli L58058.

Double infection of tobacco plants by two complementing octopine T-region mutants of Agrobacterium tumefaciens.

The molecular basis of complementation by a mixture of two different types of octopine T-region mutants (LBA4060 and LBA4210) was studied. Six randomly chosen cellular clones derived from a tumor obtained after mixed infection were analyzed for their T-DNA content via Southern blot hybridization. The clones appeared to contain T-DNA that originated from each of both mutants, indicating that they developed from doubly infected single cells.

T-DNA organization in homogeneous and heterogeneous octopine-type crown gall tissues of Nicotiana tabacum.

Octopine-type tumor tissue was obtained both by infection of plants or isolated protoplasts with Agrobacterium tumefaciens and by somatic hybridization of normal and crown gall tobacco cells. Analysis of T-DNA by Southern blotting of clones and uncloned tissue reveals that, whereas tumors induced on plants are heterogeneous mixtures of cells differing in T-DNA organization, each tissue derived from transformed protoplasts or from somatic hybridization is homogeneous. Detailed analysis of T-DNA organization showed that TL- or "core" T-DNA was always present at one or two copies per diploid genome.

Differential expression of crown gall tumor markers in transformants obtained after in vitro Agrobacterium tumefaciens-induced transformation of cell wall regenerating protoplasts derived from Nicotiana tabacum.

To obtain transformation of plant cells, we incubated 3-day-old cell wall-regenerating protoplasts from tobacco with Agrobacterium tumefaciens harboring tumor-inducing plasmids. Putative transformed tobacco cells were selected by phytohormone autotrophic growth and were shown to be transformed by the detection of the tumor cell specific enzymes lysopine dehydrogenase or nopaline dehydrogenase. This was substantiated by the detection, in transformed tumor tissues, of DNA sequences homologous to sequences in the tumor-inducing plasmid.

Retention of tumor markers in F1 progeny plants from in vitro induced octopine and nopaline tumor tissues.

Tumorous tobacco shoots have been derived from callus tissues produced by Agrobacterium tumefaciens--induced transformation of tobacco protoplasts and by fusion of normal protoplasts with those from crown gall tumors. The continued presence of T-DNA sequences in shoots is directly demonstrated by Southern blotting and is also revealed by the presence of the tumor markers octopine and nopaline. When grafted onto normal tobacco plants, both octopine- and nopaline-type shoots (including those from somatic hybrids) produced flowers and set seed.

The expression of tumour markers in intraspecific somatic hybrids of normal and crown gall cells from Nicotiana tabacum.

Following fusion of protoplasts from crown gall tumour calli, characterized by hormone independent growth, and protoplasts from normal tissues of a streptomycin-resistant mutant, SR1, we selected hormone independent streptomycin-resistant calli in Nicotiana tabacum. The tumour line, B6S3, lost the ability to form shoots. Some of the selected lines, similar to SR1, however, are morphogenic.