While some areas will begin planting soybean aphid-resistant plants this coming season, growers in Ohio will have to wait a little longer. A soybean plant introduction (PI) has been found to show resistance to soybean aphid in that state, paving the way to control the insect through new resistant cultivars as soon as 2010.
The soybean PI, labeled PI 243540, contains a single dominant gene — named Rag2 — that allows the plant to resist soybean aphid feeding and aphid colonization. This finding is the latest in a series of national research efforts to more effectively manage soybean aphid. The University of Illinois, Michigan State University, and Kansas State University have all identified their own soybean plant lines that show resistance to soybean aphid.
Actually, the new plant line was identified after a known soybean aphid-resistant plant developed by the University of Illinois failed to produce the desired results in Ohio. Scientists realized that the soybean aphid biotype in Ohio was different than the one in Illinois and could overcome resistance to Illnois’ Rag1 gene, not all that surprising since soybean aphids are capable of developing new bioteypes very rapidly.
The scientists at Ohio State University‘s Ohio Agricultural Research and Development Center are working to develop a food-grade soybean cultivar that the Ohio biotype won’t colonize. The research is designed to transfer the Rag2 gene into susceptible soybean varieties and test their resistance to the aphid in both the greenhouse and in the field. Researchers are seeing promising results and hope to have breeding lines available for release by the end of 2010 if agronomic characteristics — such as yield and resistance to major diseases — hold up.
In addition to PI 243540, other soybean plant introductions that show resistance to soybean aphid have been identified by the Ohio scientists, albeit on a moderate level. The hope is that those findings can be used to develop partial-resistant soybean cultivars, whereby multiple genes rather than a single, dominant gene define resistance.
Soybean cultivars containing the Rag1 gene should be commercially available beginning next year. However, these cultivars are not recommended for Ohio growers. If they choose to plant these new cultivars, their control option will still be to spray insecticides when aphid populations reach threshold.
(Source: The Ohio State University)