Location: Crop Genetics Research Unit
Title: Glycine accessions evaluated for resistance to Rotylenchulus reniformis Authors
Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: August 12, 2012
Publication Date: December 1, 2012
Citation: Stetina, S.R., Ray, J.D., Smith, J.R. 2012. Glycine accessions evaluated for resistance to Rotylenchulus reniformis. Journal of Nematology. 44:493. Technical Abstract: Identification of resistance to reniform nematode (Rotylenchulus reniformis) is the first step in developing resistant soybean (Glycine max) cultivars that will benefit growers in the Mid South, where soybean acreage on reniform nematode-infested fields has increased in recent years. Seventy-five domestic and wild soybean (Glycine max and G. soja) lines were evaluated for resistance to infection by reniform nematode in a series of growth chamber tests. Each entry was evaluated in at least two tests using a completely randomized design with 5 replications. A single plant of each soybean line was established in a container filled with 120 cm3 of a steam-sterilized soil mixture. Four weeks after 1,000 vermiform reniform nematodes were added to the soil, the number of swollen females attached to the roots was determined. Classification of entries was based on the percentage of infection as compared to the susceptible genotypes Morsoy RTS4706N (sets 1 and 3), Delta King DK4968 (sets 1, 2, and 3), Braxton (sets 4 and 5), and PI 88788 (sets 4 and 5): nematode index <10% = resistant, 10-30% = moderately resistant, 31-60% = moderately susceptible, and >60% = susceptible. Both relative infection and consistency of phenotype across tests contributed to identification of the best materials. This project is the first to report on the reaction of 36 genotypes to reniform nematode. Of these, eight with moderate resistance were identified: released germplasm lines DS-880 and DS4-SCN05; accessions PI 417077, PI 507354, and PI 567516 C; and breeding lines DS97-84-1, 02011-126-1-1-2-1, and 02011-126-1-1-5-1. The remaining 28 previously untested lines were classified as moderately susceptible or susceptible to the reniform nematode. In a separate experiment, reniform nematode reproduction was evaluated on a subset of the lines originally tested to confirm their response: PI 90763, PI 230977, PI 417050, PI 567516 C, DS-880, DS97-84-1, DS4-SCN05, 2011-126-1-1-2-1, and 2011-126-1-1-5-1. This growth chamber experiment was conducted 3 times. Eight weeks after soil infestation with1,000 vermiform reniform nematodes, nematodes extracted from soil plus eggs extracted from roots were counted for each entry and compared to susceptible lines Braxton and PI 88788 and resistant lines Hartwig and PI 437654 using ANOVA and differences of least squares means. A fallow treatment was included to monitor survival of the nematode with no plant roots present. PI 90763, PI 567516 C, DS-880, DS97-84-1, DS4-SCN05, 2011-126-1-1-2-1, and 2011-1-1-5-1 consistently suppressed reniform nematode populations to levels comparable to those that developed on the resistant controls. Further, in two of the three tests, the reniform nematode populations on all of these lines were equivalent to or smaller than the population that persisted in the fallow pots. Infection-based screening results indicated that PI 230977 was moderately resistant and PI 417050 was moderately susceptible. However, both of these lines were grouped with the susceptible controls when infection, reproduction, and survival of the nematodes contributed to the classification.