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ARS Home » Midwest Area » Urbana, Illinois » Soybean/maize Germplasm, Pathology, and Genetics Research » Research » Publications at this Location » Publication #156496
Title: EVALUATION OF SOYBEAN RESISTANCE TO SCLEROTINIA STEM ROT USING RECIPROCAL GRAFTING

Author
item VUONG, T - UNIV OF ILLINOIS
item Hartman, Glen

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2004
Publication Date: 8/1/2004
Citation: Vuong, T.D., Hartman, G.L. 2004. Evaluation of soybean resistance to sclerotinia stem rot using reciprocal grafting. Plant Disease; 2004.

Interpretive Summary: Sclerotinia stem rot of soybean is one of the major soybean diseases in the North Central region of the United States. One disease management option is to plant cultivars that have partial resistance. Resistant and susceptible soybean genotypes were grafted in different shoot and rootstock combinations of self-, single- or double-scion grafts to determine if the resistant mechanism is in plant shoots or roots. It was found that a resistant or susceptible response was consistently associated with resistant or susceptible shoots and not roots. This information is useful to scientists studying the mechanism of plant resistance to fungi.

Technical Abstract: Sclerotinia stem rot of soybean is one of the major soybean diseases in the North Central region of the United States. Although sources of partial resistance have been identified, information pertaining to the nature of resistance to Sclerotinia stem rot is limited. The objective of this study was to determine the expression of resistance by using combinations of susceptible and partially resistant shoots. Resistant and susceptible soybean genotypes were grafted in different shoot and rootstock combinations of self-, single- or double-scion grafts. After successful grafts were made, cotyledons were inoculated with a plug of fungal mycelium. Based on seven grafting combinations of cross- and self-grafted plants using two soybean cultivars, grafts with NKS19-90 (partially resistant) as shoots had greater (P < 0.05) plant survival than the other graft combinations. In another experiment, a total of 17 graft combinations were generated using resistant plant introductions, PI549.076A, PI503.336, and PI194.639, and two susceptible cultivars, Alpha and Merit. Resistant self-grafts of PI194.639, PI503.336, and PI549.076A, had greater (P < 0.05) plant survival than those of Alpha or Merit. Most inter-genotypic grafts with resistant shoots had greater plant survival than those in reciprocal combinations. A resistant or susceptible response was consistently associated with resistant or susceptible shoots regardless of the rootstock, type of grafting technique, or inoculation method, indicating that shoot are expression of partial resistance to S. sclerotiorum is not affected by root characteristics.