No choice but to find resistance to soybean aphid biotype 4

Authors: CONZEMIUS, SOPHIA - South Dakota State University; Hesler, Louis; VARENHORST, ADAM - South Dakota State University; TILMON, KELLEY - The Ohio State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/2017
Publication Date: 5/22/2017
Citation: Conzemius, S., Hesler, L.S., Varenhorst, A.J., Tilmon, K. 2017. No choice but to find resistance to soybean aphid biotype 4. North Central Branch Meeting, Entomological Society of America, Indianapolis, IN June 6, 2017. Available: esa.confex.com/esa/2017ncb/meetingapp.cgi/Paper/120683.

Interpretive Summary: Host plant resistance in soybean uses its natural defenses to limit injury by a major pest, the soybean aphid (SBA), and thereby reduces reliance on insecticides. Specific genes called Rag genes (Resistance to Aphis glycines) are unfavorable to SBA and may suppress their development and reproduction. However, SBA’s ability to overcome Rag genes led to biotypes that can overcome some of the resistance genes. Biotype 4can colonize and injure soybean plants with the genes Rag 1 and Rag 2 and partially resistant to Rag 3. In this study, soybean lines with known resistance to the avirulent SBA biotype 1 were screened and rated against SBA biotype 4. Accessions with the lowest ratings were followed-up with two no-choice tests that confined SBA on test plants for 20 days. Two highly resistant accessions, PI 437696 and PI 588000 differed from all other soybean accessions and the Rag 3 control in having lower SBA infestations. These experiments will be repeated to ensure that resistance holds against other SBA biotype 4 colonies from other locations and years. The strong resistances identified in our results could facilitate the development of aphid resistant soybean, protecting yield loss and input costs.

Technical Abstract: Host plant resistance in soybean [Glycine max (L.) Merr] utilizes its natural defenses to limit soybean aphid (Aphis glycines Matsamura, SBA) injury, reducing insecticide reliance. Specific genes called Rag or Resistance to Aphis glycines are unfavorable to SBA and may suppress their development and reproduction. However, divergences in SBA’s ability to overcome Rag genes led to biotype separation; biotype 4 is virulent to major genes Rag 1 and Rag 2 and partially resistant to Rag 3. In this study, soybean accessions with known resistance to the avirulent SBA biotype 1 were screened and rated against an iso-female SBA biotype 4 colony. Accessions with the lowest ratings were followed-up with two no-choice tests (NC1 and NC2) that confined SBA on test plants for 20 days. Two highly resistant accessions, PI 437696 (meanNC1 ± SE= 6.6 ± 1.5 SBA) and PI 588000 (meanNC2 ± SE= 50.1 ± 12.4 SBA), differed from all other soybean accessions and the Rag 3 control (meanNC1 ± SE= 174.3 ± 29.0, meanNC2 ± SE= 323.6 ± 70.5 SBA; ‘LD14-3039’). These experiments will be repeated to ensure that resistance holds against SBA biotype 4 iso-female colonies from other locations and years. The strong resistances identified in our results could facilitate the development of aphid resistant soybean, protecting yield loss and input costs.