Brief Summary of Minutes of Annual Meeting

Project activities are diverse and articulated in four objects. Project activities involve research spanning from basic molecular research into nematode genetics to nematode control in the field. Our accomplishments will be organized and reported under each of the four project objectives. Characterization of Nematode Genetic and Biological Variation Relevant to Crop Production and Trade Populations of Heterodera glycines across areas differ because of the soybean resistance deployed. SCN distribution increases exponentially with the deployment of resistant hosts. The longer plant resistance is used, the higher the proportion of populations which can reproduce on the standard sources of resistance.The greatest variability in H. glycines population characterization was in Ontario, Canada where plant resistance had been used for the shortest time period. A microarray comparative genomic analysis can identify genes of interest in resistant and susceptible soybeans which can then be used to affect nematode control in soybean and potentially other crops. Root-knot nematode is difficult to control in the many plants that are infected. However host-plant resistance is available. In papaya, Meloidogyne javanica reproduction ranged from 14 to 60 (with standard deviations from 21 to 96). Maradol, Kapoho, and breeding Line D had similar low Rf values. Sunrise, Saipan, and Vietnamese had similar Rf values twice as high as the Maradol group (Rf = 29). The last group of breeding lines average Rf values 3.5 times greater than the Maridol group. Currently, none of the widely grown potato cultivars are resistant to M. chitwoodi. New breeding lines with tuber- or rootspecific resistance genes from Solanum bulbocastanum are being evaluated. At present, the only available method to separate M. chitwoodi races and pathotypes is to conduct differential host test. These assays are time-consuming and cannot be performed with single nematodes. Our goal is to develop molecular methods to rapidly differentiate M. chitwoodi populations. Using microsatellites and random primers, we have found significant genetic diversity among M. chitwoodi races and pathotypes. We are currently trying to develop specific primers for sequence characterized amplified regions (SCAR) that would allow us to differentiate M. chitwoodi races and pathotypes by PCR. Rotylenchulus renifromis is also a challenging nematode to control. Twenty eight varieties of Vigna unguiculata, cowpea, were tested for host status to R. reniformis. Nematode Rf ranged from 0.04 to 1.17 on the cowpea after in screening in the greenhouse. The most resistant varieties were IT84S-2049, IT95K-1491 Danila, IT90K-284-2, IT98K-555-1, IT97K-499-39, and TVu7778. These plants had low Rf values and supported less than 205 eggs/g root tissue. The most susceptible cowpea tested was UCR 288. New soybean cultivars and breeding lines are evaluated for renifrom nematode resistance in Arkansas. Of the 161 varieties screened, 6 had with less reproduction than resistant varieties Hartwig and Anand and 5 are probably useful in a rotation. Of the 69 breeding lines evaluated, 12 were as good as the worst resistant variety. Determination of Nematode Adaptation Processes to Hosts, Agro-Ecosystems and Environments Nematodes seem to move into new areas with relative ease. The "ease" may actually be a reflection of our knowledge. A previously unrecognized M. chitwoodi pathotype has been identified that can overcome new potato resistance genes. Potatoes collected from local markets were infected by root-knot nematodes. As processing plants are reduced in number and become concentrated, tare soil is transported longer distances increasing the movement of nematodes. This can unintentionally introduce nematodes in to new areas. A recently identified population of Globodera is being evaluated for host range and other biological parameters. This population appears to be a new species. Rotylenchulus reniformis is correlated with soil type and water. As root biomass increases, so does the nematode population. It has become clearly important to kill cotton after harvest. This will prevent a final generation of R. reniformis from developing on the harvested cotton and increasing the total nematode population in the field. The identification of nematodes is important and large amounts of molecular data have been generated to identify nematodes over the last decade. The challenge is to now link data from the separate DNA markers like CO1, D2-D3, IGS, ITS, and 18s. This will aid in the identification of new species discovered from surveys and screenings. A nematode collection can be an invaluable resource in identifying new introductions or changes in a nematode over time. Maintenance of a nematode collection is not without expenses. Maintenance of living cultures is an expensive endeavor and cryopreservation is a less expensive alternative. However cryopreservation is not free. Funding is needed to support these valuable resources. Development and Assessment of Nematode Management Strategies in Agricultural Production Systems Nematode control is challenging for growers and producers. However our project is identifying tools and techniques that offer effective, environmentally sound and sustainable control. In a SCN rotation, Anand depressed the SCN population and gave higher yields. Rotating the resistance reactions will eventually reduce the SCN levels and not cause new SCN races to form. Pasteuria nishizawae has been found on SCN and can now be cultured in fermentation tanks. In open pollinated crops, F2 or later generations may not have the same levels of resistance as in the F1 or F0. We are finding evidence that such a loss may be occurring in the Coffea liberica used to control Meloidogyne konaensis. Implementation of Rapid Information Transfer of Project Results to Stakeholder In striving to rapidly disseminate information and knowledge generated by the project, we are increasing turning to electronic publication. The status of soybean cultivars to H. glycines are published on line. Information is also disseminated in traditional hard copy paper form. We are transferring findings to stakeholders via telephone, internet, mailings and publication, We are presenting at conferences, workshops and meetings. We are reaching growers, extension personnel, other scientists, and interested people employing these methods.