@article{fraher_schwarz_heim_gesteira_mollinari_pereira_zeng_brown-guedira_gorny_yencho_2024, title={Discovery of a major QTL for resistance to the guava root-knot nematode (<i>Meloidogyne enterolobii</i>) in 'Tanzania', an African landrace sweetpotato (<i>Ipomoea batatas</i>)}, volume={137}, ISSN={["1432-2242"]}, DOI={10.1007/s00122-024-04739-1}, abstractNote={Sweetpotato, Ipomoea batatas (L.) Lam. (2n = 6x = 90), is among the world's most important food crops and is North Carolina's most important vegetable crop. The recent introduction of Meloidogyne enterolobii poses a significant economic threat to North Carolina's sweetpotato industry and breeding resistance into new varieties has become a high priority for the US sweetpotato industry. Previous studies have shown that 'Tanzania', a released African landrace, is resistant to M. enterolobii. We screened the biparental sweetpotato mapping population, 'Tanzania' x 'Beauregard', for resistance to M. enterolobii by inoculating 246 full-sibs with 10,000 eggs each under greenhouse conditions. 'Tanzania', the female parent, was highly resistant, while 'Beauregard' was highly susceptible. Our bioassays exhibited strong skewing toward resistance for three measures of resistance: reproductive factor, eggs per gram of root tissue, and root gall severity ratings. A 1:1 segregation for resistance suggested a major gene conferred M. enterolobii resistance. Using a random-effect multiple interval mapping model, we identified a single major QTL, herein designated as qIbMe-4.1, on linkage group 4 that explained 70% of variation in resistance to M. enterolobii. This study provides a new understanding of the genetic basis of M. enterolobii resistance in sweetpotato and represents a major step towards the identification of selectable markers for nematode resistance breeding.}, number={10}, journal={THEORETICAL AND APPLIED GENETICS}, author={Fraher, Simon and Schwarz, Tanner and Heim, Chris and Gesteira, Gabriel De Siqueira and Mollinari, Marcelo and Pereira, Guilherme Da Silva and Zeng, Zhao-Bang and Brown-Guedira, Gina and Gorny, Adrienne and Yencho, G. Craig}, year={2024}, month={Oct} }
 @article{schwarz_chitra_jennings_gorny_2024, title={Evaluation of Weed Species for Host Status to the Root-Knot Nematodes <i>Meloidogyne enterolobii</i> and <i>M. incognita</i> Race 4}, volume={56}, ISSN={["2640-396X"]}, DOI={10.2478/jofnem-2024-0017}, abstractNote={Abstract Weeds that compete with valuable crops can also host plant-parasitic nematodes, acting as a source of nematode inoculum in a field and further damaging crops. The host status of 10 weed species commonly found in North Carolina, USA, was determined for the root-knot nematodes Meloidogyne enterolobii and M. incognita race 4 in the greenhouse. Each weed species was challenged with 5,000 eggs/plant of either M. enterolobii or M. incognita race 4, with five replicate plants per treatment in two separate greenhouse trials. Root galling severity and total number of nematode eggs per root system were recorded 60 days after inoculation. Reproduction factor (Rf = final nematode population/initial nematode population) was calculated to determine the host status of each weed species to M. enterolobii and M. incognita race 4. Four weed species ( Datura stramonium, Digitaria sanguinalis, Senna obtusifolia, and Cyperus esculentus ) were poor hosts (Rf < 1) to both nematode species, and roots of these weed plants did not display galling. Four weed species ( Ipomoea hederacea, Amaranthus palmeri, Portulaca pilosa, and Ipomoea lacunosa ) were hosts (Rf > 1) to both nematode species, and all had observable root gall formation. Sida rhombifolia and Cyperus rotundus were poor hosts to M. enterolobii but susceptible hosts to M. incognita . This study documents a differential host status of some common weeds to M. enterolobii and M. incognita race 4, and these results highlight the necessity of managing root-knot nematodes through controlling weeds in order to protect valuable crops.}, number={1}, journal={JOURNAL OF NEMATOLOGY}, author={Schwarz, Tanner and Chitra and Jennings, Katherine and Gorny, Adrienne}, year={2024}, month={Mar} }
 @article{schwarz_gorny_2024, title={Evaluation of Soybean Genotypes (<i>Glycine max</i> and <i>G. soja</i>) for Resistance to the Root-Knot Nematode, <i>Meloidogyne enterolobii</i>}, volume={108}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-02-23-0278-RE}, abstractNote={ Potential resistance to the root-knot nematode (RKN) Meloidogyne enterolobii in 72 Glycine soja and 44 G. max soybean genotypes was evaluated in greenhouse experiments. Approximately 2,500 eggs of M. enterolobii were inoculated on each soybean genotype grown in a steam sterilized 1:1 sand to soil mixture. Sixty days postinoculation, plants were destructively harvested to determine the host status. The host status of each soybean genotype was determined by assessing root galling severity and calculating the final eggs per root system divided by the initial inoculum, or the reproduction factor (Rf). Five G. soja soybean genotypes were identified as resistant (Rf < 1) to M. enterolobii: ‘407202’, ‘407239’, ‘424083’, ‘507618’, and ‘639621’. None of the tested G. max soybean genotypes were identified as resistant to M. enterolobii. Some of the G. max genotypes determined to be susceptible to M. enterolobii include ‘Hagood’, ‘Avery’, ‘Rhodes’, ‘Santee’, and ‘Bryan’. The genotype ‘Bryan’ had the lowest Rf values among the group at 5.06 and 6.67 in two independent trials, respectively, which represents a five- to sixfold increase in reproduction of M. enterolobii. Plant genotypes resistant to RKNs are effective in managing the disease and preserving yield, cost-efficient, and environmentally sustainable, and host resistance is often regarded as the most robust management tactic for controlling plant-parasitic nematodes. Resistance to RKNs in soybean genotypes has been identified for other Meloidogyne species, yet there is currently limited data regarding soybean host status to the highly aggressive nematode M. enterolobii. This study adds to the knowledge of potential native resistance to M. enterolobii in wild and cultivated soybean. }, number={3}, journal={PLANT DISEASE}, author={Schwarz, Tanner and Gorny, Adrienne}, year={2024}, month={Mar}, pages={694–699} }
 @article{saha_schwarz_mowery_gorny_2023, title={Reaction of Winter Cover Crops to Meloidogyne enterolobii and Glasshouse Bioassay for Evaluating Utility in Managing M. enterolobii in Soybeans}, volume={55}, ISSN={["2640-396X"]}, DOI={10.2478/jofnem-2023-0014}, abstractNote={Abstract
               
                  Meloidogyne enterolobii is an invasive and highly aggressive root-knot nematode pathogen impacting the Southeastern United States. Winter cover cropping may be a cost-effective method for reducing populations of M. enterolobii in between summer cash crops, yet a gap in the knowledge remains about the response of these cover crops to M. enterolobii and their utility in suppressing nematode populations prior to a cash crop. A “two-step” glasshouse bioassay was performed to evaluate eight winter cover crops popular in North Carolina for their direct response to M. enterolobii infection, and to quantify their effect in reducing nematode populations for the following soybean plants. Data on cover crop root galling, soybean root galling, soybean shoot fresh weight, soybean root fresh weight, eggs per gram of soybean root, and a modified reproductive factor were collected. Cereal cover crops did not display root galling, and there was significantly less root galling in those soybean plants following cereal winter cover crops when compared to those following broadleaf winter cover crops. Broadleaf winter cover crops resulted in significantly higher eggs per gram of soybean root and modified reproductive factor in the soybean plants, compared to cereal cover crops and non-inoculated controls. Results from this study suggest that cereal winter cover crops may be poor-hosts to M. enterolobii and may significantly reduce M. enterolobii populations before a soybean crop, compared to broadleaf winter cover crops. This study lays the groundwork for management recommendations and future field trials to assess management of M. enterolobii through winter cover cropping.}, number={1}, journal={JOURNAL OF NEMATOLOGY}, author={Saha, Neel and Schwarz, Tanner and Mowery, Samantha and Gorny, Adrienne M.}, year={2023}, month={Feb}, pages={1–10} }
 @article{schwarz_li_ye_davis_2020, title={Distribution of Meloidogyne enterolobii in Eastern North Carolina and Comparison of Four Isolates}, volume={21}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-12-19-0093-RS}, abstractNote={ The guava root-knot nematode (RKN), Meloidogyne enterolobii, is a particularly aggressive pathogen with limited known distribution in the United States. In 2011, M. enterolobii was identified on field crops in North Carolina for the first time. In collaboration with the North Carolina Department of Agriculture and Consumer Services Nematode Assay Laboratory, RKN-positive samples from the eastern half of North Carolina submitted to the laboratory were analyzed for Meloidogyne species identification using polymerase chain reaction (PCR) of individual nematodes. PCR primers specific for Meloidogyne incognita, M. javanica, M. arenaria, M. hapla, and M. enterolobii were used to analyze DNA from 203 RKN-positive samples representing a variety of field and vegetable crops grown in counties in the eastern half of North Carolina. M. incognita was the predominant species identified (32% of samples), and M. enterolobii was identified in 6% of samples including ones from sweetpotato, tobacco, and soybean crops. New detections of M. enterolobii were found in Nash, Greene, Sampson, and Harnett counties in addition to the previously identified locations in Johnston, Wayne, Columbus, and Wilson counties. Four isolates of M. enterolobii populations were collected from soybean and sweetpotato crops in Johnston, Greene, and Wilson counties and reared on ‘Rutgers’ tomato plants in the greenhouse. Potential differences in virulence among the four M. enterolobii populations were not detected in greenhouse infection assays on six selected resistant and susceptible sweetpotato genotypes in two independent tests. }, number={2}, journal={PLANT HEALTH PROGRESS}, author={Schwarz, Tanner and Li, Chunying and Ye, Weimin and Davis, Eric}, year={2020}, pages={91–96} }
 @article{schwarz_li_yencho_pecota_heim_davis_2021, title={Screening Sweetpotato Genotypes for Resistance to a North Carolina Isolate of Meloidogyne enterolobii}, volume={105}, ISSN={0191-2917 1943-7692}, url={http://dx.doi.org/10.1094/PDIS-02-20-0389-RE}, DOI={10.1094/PDIS-02-20-0389-RE}, abstractNote={ Potential resistance to the guava root-knot nematode, Meloidogyne enterolobii, in 91 selected sweetpotato (Ipomoea batatas [L.] Lam.) genotypes was evaluated in six greenhouse experiments. Ten thousand eggs of M. enterolobii were inoculated on each sweetpotato genotype grown in a 3:1 sand to soil mixture. Sixty days after inoculation, the percentage of total roots with nematode-induced galls was determined, and nematode eggs were extracted from roots. Significant differences (P < 0.001) between sweetpotato genotypes were found in all six tests for gall rating, total eggs, and eggs per gram of root. Resistant sweetpotato genotypes were calculated as final eggs per root system divided by the initial inoculum, where Pf/Pi < 1 (reproduction factor; final egg count divided by initial inoculum of 10,000 eggs), and statistical mean separations were confirmed by Fisher’s least significant difference t test. Our results indicated that 19 out of 91 tested sweetpotato genotypes were resistant to M. enterolobii. Some of the susceptible genotypes included ‘Covington,’ ‘Beauregard,’ ‘NCDM04-001’, and ‘Hernandez.’ Some of the resistant sweetpotato genotypes included ‘Tanzania,’ ‘Murasaki-29,’ ‘Bwanjule,’ ‘Dimbuka-Bukulula,’ ‘Jewel,’ and ‘Centennial.’ Most of the 19 resistant sweetpotato genotypes supported almost no M. enterolobii reproduction, with <20 eggs/g root of M. enterolobii. A number of segregants from a ‘Tanzania’ × ‘Beauregard’ cross demonstrated strong resistance to M. enterolobii observed in the ‘Tanzania’ parent. In collaboration with North Carolina State University sweetpotato breeding program, several genotypes evaluated in these tests are being used to incorporate the observed resistance to M. enterolobii into commercial sweetpotato cultivars. }, number={4}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Schwarz, Tanner R. and Li, Chunying and Yencho, G. Craig and Pecota, Kenneth V and Heim, Chris R. and Davis, Eric L.}, year={2021}, month={Apr}, pages={1101–1107} }
 @article{hajihassani_rutter_schwarz_woldemeskel_ali_hamidi_2020, title={Characterization of Resistance to Major Tropical Root-Knot Nematodes (Meloidogyne spp.) in Solanum sisymbriifolium}, volume={110}, ISSN={["1943-7684"]}, DOI={10.1094/PHYTO-10-19-0393-R}, abstractNote={ Root-knot nematodes (Meloidogyne spp.) are important contributors to yield reduction in tomato. Though resistant cultivars to common species (Meloidogyne arenaria, M. incognita, and M. javanica) are available, they are not effective against other major species of root-knot nematodes. Cultivars or lines of Solanum sisymbriifolium were examined to assess the presence and level of resistance to five major species: M. arenaria race 1, M. incognita race 3, M. haplanaria, M. javanica, and M. enterolobii. Differences in S. sisymbriifolium response to the nematode infection were apparent when susceptibility or resistance was classified by the egg counts per gram fresh weight of root and the multiplication rate of the nematodes. The cultivar Diamond was highly susceptible, Quattro and White Star were susceptible, while Sis Syn II was resistant to M. arenaria. Quattro, White Star, and Sis Syn II exhibited a moderate to high level of resistance to M. incognita but the nematode increased 2.5-fold from the initial population of the M. incognita on Diamond. All S. sisymbriifolium cultivars were highly resistant to both M. haplanaria and M. enterolobii, while highly susceptible to M. javanica. A microplot study under field conditions using Sis Syn II confirmed that M. arenaria, M. incognita, and M. haplanaria were not pathogenic on the plant. Likewise, an examination on cross-sections of galled root tissues confirmed the susceptibility and resistance of S. sisymbriifolium lines to Meloidogyne spp. Using S. sisymbriifolium as a resistant rootstock or a new source of resistance may result in the development of nonchemical and sustainable management strategies to protect the tomato crop. }, number={3}, journal={PHYTOPATHOLOGY}, author={Hajihassani, Abolfazl and Rutter, William B. and Schwarz, Tanner and Woldemeskel, Moges and Ali, Md Emran and Hamidi, Negin}, year={2020}, month={Mar}, pages={666–673} }