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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Genetics Research » Research » Publications at this Location » Publication #349440

Research Project: Introgression of Novel Resistant Genes and Development of Integrated Production Systems for Managing Reniform Nematodes in Cotton

Location: Crop Genetics Research

Title: Reproduction and pathogenicity of endemic populations of Rotylenchulus reniformis on cotton

Author
item KHANAL, CHURAMANI - Louisiana State University
item MCGAWLEY, EDWARD - Louisiana State University
item OVERSTREET, CHARLES - Louisiana State University
item Stetina, Salliana - Sally
item MYERS, GERALD - Louisiana State University
item KULARATHNA, MANJULA - Louisiana State University
item MCINNES, BENJAMIN - Louisiana State University
item GODOY, FELIPE M. - Louisiana State University

Submitted to: Nematropica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2018
Publication Date: 6/1/2018
Citation: Khanal, C., McGawley, E.C., Overstreet, C., Stetina, S.R., Myers, G.O., Kularathna, M., McInnes, B., Godoy, F.C. 2018. Reproduction and pathogenicity of endemic populations of Rotylenchulus reniformis on cotton. Nematropica. 48:68-81.

Interpretive Summary: The reniform nematode is a microscopic worm that feeds on the roots of upland cotton and causes significant yield loss in the southern United States. Little is known about variability among populations of this nematode in Louisiana with respect to its ability to infect, reproduce, and cause damage to the cotton crop. In greenhouse and microplot trials comparing populations from four parishes in Louisiana (West Carroll, Rapides, Morehouse, and Tensas) on cotton lines resistant or susceptible to the nematode, variation was documented. Across all cotton lines, the Morehouse and Rapides populations had the greatest and least reproduction, respectively. Reproduction was directly associated with crop damage, with the Morehouse population causing the greatest reductions in plant weight, number of bolls, seed cotton weight, and lint weight, and the Rapides population causing the least damage. The variability documented in these populations underscores the importance of using a range of reniform nematode populations by cotton breeders aiming to develop cotton varieties with resistance to this pest.

Technical Abstract: The reniform nematode (Rotylenchulus reniformis) is the predominant parasitic nematode of upland cotton (Gossypium hirsutum) in the southern United States. Little is known about variability in geographic isolates of reniform nematode. In order to evaluate the comparative reproduction and pathogenicity of reniform nematode populations endemic in Louisiana, a series of microplot and greenhouse experiments were conducted. Reniform nematode populations derived from single-egg masses collected form West Carroll (WC), Rapides (RAP), Morehouse (MOR) , and Tensas (TEN) parishes were used in full-season (150 days) microplot, and 60-day greenhouse experiments, each repeated once. Data from two microplot trials, averaged over 2 years, showed significant differences among isolates of reniform nematode in both reproduction and pathogenicity on upland cotton cultivars Phytogen 499 WRF, Deltapine 1133 B2RF, and Phytogen 333 WRF. Across all cotton cultivars, the MOR and RAP isolates had the greatest and the least reproduction value of 331.8 and 230.2, respectively. Reduction in plant dry weight, number of bolls, seed cotton weight, and lint weight was the greatest and the least for MOR and RAP isolates, respectively. MOR and RAP isolates lowered plant dry weights of cotton by 55%, and 9%, respectively. Reproduction and pathogenicity of the WC and TEN isolates were intermediate. Data from greenhouse trials showed results similar to that of microplot trials. In greenhouse experiments, reproduction of MOR and RAP isolates across all cotton genotypes was the greatest (reproductive value of 10.7) and the least (reproductive value of 7.9), respectively. Although reproductions of reniform nematode were lower in the germplasm lines than the cultivars, the germplasm lines sustained greater plant weight loss. The variability in reproduction and pathogenicity among endemic populations of reniform nematode in both the microplot and greenhouse experiments adds further support to the hypothesis that virulence phenotypes of R. reniformis exist.