Brief Summary of Minutes of Annual Meeting

The project has four objects. Project activities are diverse and cover a wide range of agroecosystems. Project activities involve research spanning from basic molecular research into nematode genetics to applied control in cooperative field tests. 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 A range of crops and plant-parasitic nematodes important in the western region were evaluated by project members. Recently developed soybean cultivars and breeding lines were evaluated for resistance to the soybean cyst nematode, the reniform nematode. Several lines and cultivars show promise with resistance equal to or greater than that currently deployed. Cotton has also been evaluated against reniform nematode and root-knot nematodes. Root-knot nematode (Meloidogyne spp.) interactions with resistance genes in the host crops cowpea (Vigna unguiculata), Lima bean (Phaseolus lunatus), and cotton (Gossypium spp.) were examined to determine specificity of nematode responses to different resistance genes in these crop plants. These studies are coupled with efforts to breed new varieties with improved nematode resistance. New resistance sources have been identified in each of these crop species that confer unique specificities that match avirulence genes in the nematode. Field screens of multiple advanced Lima bean breeding lines were conducted in fields infested with M. incognita and M. javanica. Several lines were found to be resistant to either one or both nematodes, and seed was collected for further advancement. The previous findings of at least three independent genes conferring resistance in the Lima pedigrees was supported by these field selection screenings. In cowpea, a consensus genetic map was developed based on six individual maps using six recombinant inbred line (RIL) populations. The high density map has more than 1000 EST-derived SNP markers covering the 11 linkage groups and spanning 680 cM at an average marker distance of 0.73 cM. Screening of three RIL populations segregating for the suite of Rk genes conferring M. incognita and M. javanica resistance was done in field and seedling growth pouch tests. The resistance phenotype data were used with the SNP markers for QTL mapping. Three main resistance QTL were identified on different linkage groups. The markers are gene-expression based and provide an entryway to fine mapping and isolation of the resistance genes, in conjunction with a newly constructed cowpea physical map whose BAC contigs have been SNP genotyped. The markers for the root-knot nematode resistance loci will facilitate marker-assisted breeding for nematode resistance using SNP-based high-throughput genotyping. In cotton, genetic analysis, molecular mapping, and marker development revealed a major M. incognita resistance gene, rkn1, on chromosome 11 in the upland cotton (Gossypium hirsutum) Acala NemX. In progenies derived from crosses between Acala NemX and the root-knot susceptible G. barbadense cultivar Pima S7, a significant number of individual plants were found with extremely high levels of resistance. These transgressive segregants were much more resistant than the resistant parent of the cross. Genetic and molecular marker analysis using BAC-end derived and other SSR markers revealed a gene in Pima S7, named RKN2, that when combined with rkn1 from NemX, resulted in the ultra-resistant phenotype. Genetic mapping of the markers revealed that gene RKN2 is also located on cotton chromosome 11, in the same region as rkn1. The novel resistance based on these clustered genes has important potential for improving nematode management in cotton. We continued gene action analysis by inheritance and QTL mapping and determined in both intraspecific and interspecific cotton crosses that a combination of allelic interaction, epistasis and heterosis operated in these crosses, with both additive and dominance effects revealed. These studies also refined the SSR markers, which can be used for marker assisted selection for resistance. Papaya (Carica papaya L.) trees infected with root-knot nematodes (Meloidogyne javanica) can be stunted, have lower yields, and increased sensitivity to stresses. The nematode reproduced on papaya cultivars Kapoho, Maradol, Saipan, Sunrise and Vietnam, and breeding lines UH Line D Poamoho, Richter 181.OM20-1, Richter 192.OM3-1, and Richter 192.OM3-2. In one test Saipan supported the least nematode reproduction (Rf = 0.6) whereas Richter 181.OM20-1 and Sunrise had the greatest Rfs (8.9 and 14.0 respectively). In a repeat of the test, nematode reproduction was greater on all genotypes, but the test was confounded by early plant death. The relation between nematode Pi and damage was quantified in Sunrise papaya. Sunrise root and shoot weight decreased with increasing nematode Pi, such that plant dry weight = 23g - 0.00015(Pi). Papaya genotypes differ in their response to M. javanica. The Hawaiian papaya cultivars are among the more susceptible genotypes to M. javanica. Damage caused by M. javanica is not especially severe on Sunrise papaya. Ten genotypes of semi-wild C. arabica were evaluated for resistance to Meloidogyne konaensis. Nine of the semi-wild genotypes had Rf values less than 1. The Rf values of the susceptible Typica and Yellow Catuai coffees were 13.1 and 15.95 respectably. The Rf value of the rootstock Fukunaga was 2.5. Some of the semi-wild coffee genotypes were very tolerant to infection whereas a few seemed to be intolerant. These semi-wild genotypes hold great promise for nematode control in coffee. ET15 (T.16704-7), ET17 (T.16706-6), ET 25B (17204-2). Due to the restricted host range of the nematode (only members of the Juglandaceae, and Quercus laurifolia), and the potential for dissemination in infected nursery stock, a study was conducted to determine the level of genetic variability among Meloidogyne partityla. M. partityla populations from AZ, GA, NM, OK, and TX were evaluated at the 5.8s rDNA and flanking ITS region and COXII  tRNA  His intergenic mtDNA region. None of the geographic locations showed significant variation in either sequence region within a location, so consensus sequences were produced for the 5.8s rDNA and mtDNA regions from each location. Neighbor-joining trees constructed for comparison of both loci across the five states, and with mtDNA sequences from Genbank, showed (as was anticipated) that greater variability among nematode populations was detected using mtDNA. Populations from NM and OK were highly similar to each other when comparing either locus, while populations from AZ, GA, and TX grouped similarly when the rDNA locus was used but the TX population separated from AZ and GA using the mtDNA locus. Sequence variation was generally very small, and no differences in behavior or pathogenicity among populations are known at this time. Cyst nematode on corn. A field on the KY-TN border has the same nematode as the find in 2006 in western TN. The only known commonality at this point is corn production and application of animal waste. Each of the three known occurrences of the nematode is at least 80 miles apart and no known link between the farms. Potato clones/varieties were screened for resistance to Columbia Root-knot Nematode and Corky Ringspot. Potato seed from 11 potato clones developed in the USDA-ARS Variety Development Program at Prosser, WA were compared to commercial varieties Ranger (R) and Russet Burbank (RB). Five clones had less than 5% of tubers expressing symptoms of CRKN compared to 20% and 55% for R and RB, respectively, and five clones had less than 5% of tubers expressing symptoms of CRS compared to 13% and 14% for R and RB, respectively. There was very little overlap in resistance to CRKN and CRS and only two clones (PA00N32-4, AOO646-4) had less than 5% CRKN and less than 5% CRS. The commercial varieties Yukon Gold, Canela, Rio Grande, Russet Nugget, Centennial, Russet Norkotah supported large population increases in CRKN with Russet Nugget having the greatest (200 fold) and Centennial the least (40 fold) increase. Centennial also had the least tuber damage (40% culls) compared to over 60% to near 90% in all other varieties. Expression of symptoms of CRS was high (>35%) in Yukon Gold, Canela and RioGrande, and low (<10%) in Centennial, Russet Nugget and Russet Norkoth. Determination of Nematode Adaptation Processes to Hosts, Agro-Ecosystems and Environments We are undertaking a morphometric and molecular characterization of genera and species of Criconemoidea. Samples from Florida, Missouri, North Carolina, Arkansas represent Mesocriconema, Criconema, Ogma, Tylenchulus (from grape in Missouri and Arkansas) Nothocriconema, criconemoides, Hemicycliophora, Hemicriconemoides, Paratylenchus, Gracilacus, Caloosia or R Loofia, Xenocriconemella and 4 more ring type nematodes for identification. Reserach on Helix aspersa (Cornu aspersum), the Brown Garden Snail, demonstrates that snails may serve as phoretic hosts for plant-parasitic nematodes. Morphological identifications of nematodes found in the snails include Aphelenchoides spp., Caenorhabditis spp., and Rhabditis spp., Aphelenchus avenae, Rhabditis terricola, Rhabditis bracisiae, and Panagrolaimus sp., Xiphnema spp., Aphelenchoides spp., and Aphelenchus avenae. The latter three nematodes are plant or fungal feeding nematodes and were recovered from the foot muscle and shell of the snail. No nematodes were recovered from the reproductive system or heart. The bacterial isolates from specific regions within the snail included preliminary matches to Serratia proteamaculans and Sphingobacterium kitahiroshimense, Stenotrophomonas maltophilia, and Serratia proteamaculans. P. putida, S. kitahiroshimense, and Escherichia coli and snail slime attracted C. elegans. Characterization of TN SCN field populations show an increase from 50% to 85% of the populations capable of reproducing on PI 88788. In the previous surveys there was no indication of the numbers of samples collected vs the number they were able to characterize. However, in the present survey, only a small percentage of samples contained or reproduced at a high rate for characterization. Pasteuria nishizawae has been recovered from field soil and a survey is currently underway. Although root-lesion (Pratylenchus spp.), cyst (Heterodera spp.) and northern root-knot (Meloidogyne hapla) are serious pests in Michigan, M. hapla is not considered economically significant in Michigan potato production. However, little information is available on the status of Michigan-grown potato cultivars against M. hapla. In view of the diverse Michigan cropping systems, movement of soil and plant material, and potential threats from quarantined nematodes (potato cysts and Columbia root-knot), it is necessary to examine the reaction of potato cultivars selected for Michigan conditions against M. hapla. The effects of four M. hapla populations (Mh 1, Mh 2, Mh 3 and Mh 4) collected from different soils and cropping systems in Michigan on three chipping (Boulder MSF373-8, MSJ461-1 and Kalkaska MSJ036-A) three tables stock (Jacqueline lee, Michigan Purple, and Snowden) potato cultivars and Rutgers tomato (control) were compared under controlled conditions. While infection was less than in tomato, the six potato cultivars were suitable hosts for the M. hapla populations. The results suggest that an M. hapla management strategy that includes a rotation of potato cultivars such as these may increase the risk to other crops. Difficult-to-control annual weeds serve as host reservoirs for M. incognita and Verticillium dahliae in the chile pepper (Capsicum annuum) system. Sspurred anoda (Anoda cristata = SA), tall morningglory (Ipomoea purpurea = TM), and Wrights groundcherry (Physalis wrightii =WG) experienced reductions in shoot or root weight in response to either M. incognita or V. dahliae. Growth of TM increased in response to infection by V. dahliae. The level of M. incognita reproduction was not reduced by V. dahliae infection of any annual weed, and increased on V. dahliae-infected SA. A microplot study of SA, TM, and WG to M. incognita infection will provide insight into the potential effect of root-knot nematode infection on the contribution of certain difficult-to-control annual weeds to the soil seed bank associated with these pests. Development and Assessment of Nematode Management Strategies in Agricultural Production Systems At the request of local producers, a study was initiated to evaluate the effectiveness of annual winter cover crops in combination with novel summer crops that were: 1) an aggressive growth habit likely to out-compete nutsedges (and/or broad registration of suitable herbicides for nutsedge suppression in the crop); 2) resistance to or poor host suitability for M. incognita; 3) potential for positive economic return to the producer. Oilseed radish (Raphanus sativus cv Boss) was selected as a winter cover crop. Cotton cv NemX HY, and a forage variety of pearl millet (Pennisetum typhoides cv Tifleaf) were selected for annual summer crops. A nondormant, M. incognita-resistant alfalfa cv Pioneer 58N57 was established as the positive control. Chile pepper will be planted as a high-value vegetable to assess the efficacy of previous crops in suppressing the weed/nematode pest complex at the conclusion of the study. Destroying Columbia root-knot nematode (Meloidogyne chitwoodi) in potato before processing will increase potato quality and address quarantine issues. Exposure of CRKNinfested tissues to chlorine in the form of bleach at concentrations up to 25,000 ppm Cl was ineffective. Boiling potato peels and water associated with peels for five minutes was effective but judged to be unacceptable to the industry. Heating potato peels and associated water to 60 ºC or above for one minute or longer was found to be an effective destruction protocol. Submersing whole tubers in water at 80 ºC for a minimum of three minutes before peeling was a reliable destruction protocol that would prevent escape of living CRKN through the peeling process. Short duration hot water treatments would be an effective method to destroy CRKN during processing. Temperatures of 50ºC (peels) to 70ºC (tubers) may be effective with longer exposure times but need testing. Studies include application of poultry litter and date of planting/MG study. In 2008 there was good correlation of NDVI readings with plant height and yield. No differences in SCN reproduction were observed in tillage or poultry litter rates. The 2009 data is still being processed. We try to communicate to producers that if they wish to continue soybean production over a number of years, they need to look at more than yield. We have included information for producers on the effects of varieties and date of planting on SCN reproduction. Effects of tillage strategies are ongoing. An undescribed bacterial parasite has been detected in this field area. Implementation of Rapid Information Transfer of Project Results to Stakeholder We timely extend information gleaned from the research objectives to a variety of clientele. Research results were disseminated to different user groups in several venues. Information is presented to extension specialists who incorporates the information into nematode recommendations. Information is also made available to agricultural producers, crop consultants, and county agents at conferences such as the Beltwide Cotton Conferences, the NM Crop Production Association; NM Vine and Wine Society; NM Chile Association Board of Directors; NM Chile Conference; and Joint AZ/NM Chile Association Field Day and the potato industry stakeholders. Results were transferred to scientific peers through presentations at national professional meetings such as the Society of Nematology/Soil Ecology Society, and the Weed Science Society of America and the Western Society of Weed Science. Results are published in peer-reviewed journals to disseminate information to scientific peers. The web is also used to present and share results of SCN screening of commercial soybean varieties.