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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATED MANAGEMENT OF PLANT-PARASITIC NEMATODES IN COTTON AND PEANUT Title: Induction of systemic acquired resistance by Rotylenchulus reniformis and Meloidogyne incognita in cotton following separate and concomitant inoculations.

Authors
item Aryal, Sudarshan -
item Davis, Richard
item Stevenson, Katherine -
item Timper, Patricia
item Ji, Pingsheng -

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 8, 2012
Publication Date: June 18, 2011
Citation: Aryal, S.K., Davis, R.F., Stevenson, K.L., Timper, P., Ji, P. 2011. Induction of systemic acquired resistance by Rotylenchulus reniformis and Meloidogyne incognita in cotton following separate and concomitant inoculations. Journal of Nematology. 43(3-4):160-165.

Interpretive Summary: Systemic acquired resistance (SAR) can be elicited by pathogens, and SAR against plant-parasitic nematodes has been documented. Our objective was to determine whether co-infection of cotton by root-knot and reniform nematodes affects the population level of either nematode compared to infection by each species individually. Split-root trials were conducted in which plants were inoculated with i) reniform nematode only, ii) root-knot nematode only, iii) both root-knot and reniform nematodes, or iv) no nematodes. Half of the root system was inoculated with reniform or root-knot nematodes on day 0 and the other half with root-knot or reniform nematodes on day 0 or day 14 depending on the experiment. Experiments were conducted on cotton cultivar DP 0935 B2RF (susceptible to both nematodes), LONREN-1 (germplasm line resistant to R. reniformis), and M-120 RNR (germplasm line resistant to M. incognita), and tests were terminated 8 wk after the last inoculation. Both soil and roots from each half of the root system were used to determine the total nematode population levels, and root galling was rated on a 0 to 10 scale. Statistical analysis indicated no differences in root galling (except on LONREN-1) or population levels when the two nematode species were introduced on the same day. When root-knot nematodes were introduced 14 d after reniform nematodes, reduction in galling (36% on DP 0935 and 33% on LONREN-1) and root-knot nematode population levels (35% on DP 0935 and 45% on LONREN-1) were significant. When reniform nematodes were inoculated 14 d after root-knot nematodes, reduction in reniform nematode population levels (18% on DP 0935 and 26% on M-120) were significant. This study documents for the first time that infection of cotton by a nematode can elicit SAR to another nematode species.

Technical Abstract: Systemic acquired resistance (SAR) can be elicited by virulent and avirulent pathogenic strains and SAR against plant-parasitic nematodes has been documented. Our objective was to determine whether co-infection of cotton by Meloidogyne incognita and Rotylenchulus reniformis affects the population level of either nematode compared to infection by each species individually. Split-root trials were conducted in which plants were inoculated with i) R. reniformis only, ii) M. incognita only, iii) both R. reniformis and M. incognita, or iv) no nematodes. Half of the root system was inoculated with R. reniformis or M. incognita on day 0 and the other half with M. incognita or R. reniformis on day 0 or day 14 depending on the experiment. Experiments were conducted on cotton cultivar DP 0935 B2RF (susceptible to both nematodes), LONREN-1 (germplasm line resistant to R. reniformis), and M-120 RNR (germplasm line resistant to M. incognita), and tests were terminated 8 wk after the last inoculation. Both soil (vermiform) and roots (egg) extracted from each half of the root system to determine the total nematode population levels, and root galling was rated on a 0 to 10 scale. Mixed models analysis and comparison of least squares means indicated no differences in root galling (except on LONREN-1) or population levels when the two nematode species were introduced on the same day. When M. incognita was introduced 14 d after R. reniformis, reduction in galling (36% on DP 0935 and 33% on LONREN-1) and M. incognita population levels (35% on DP 0935 and 45% on LONREN-1) were significant (P = 0.05). When R. reniformis was inoculated 14 d after M. incognita, reduction in R. reniformis population levels (18% on DP 0935 and 26% on M-120) were significant. This study documents for the first time that infection of cotton by a nematode can elicit SAR to another nematode species.

Last Modified: 12/18/2014
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