Novel sources of soybean aphid resistance in early maturing soybean germplasm

The soybean aphid is a destructive pest of soybean in North America because of the ability of its populations to quickly grow to damaging levels. Aphid-resistant soybean varieties have been marketed since 2009, but few options are available for growers looking for early-maturity varieties. Our objective was to provide additional sources of soybean aphid resistance in early maturity groups. In an initial screening study conducted in a growth chamber, we compared aphid populations on 75 plant introductions (PIs) originating from Asia and three lines from Minnesota not yet tested for resistance to biotype-1 soybean aphids (78 entries total) to known susceptible and resistant checks.  The new PIs and lines ranged from maturity groups (M.G) 000 to I.  Selected lines were included in choice and no-choice experiments to determine the category of resistance (i.e. antibiosis or antixenosis). Screening indicated PIs 639534A, 639537, and 605765B (all M.G. I) possessed antibiosis, while 507713 (M. G. 0) possessed antixenosis.  These additional sources of germplasm may provide soybean breeders more options for incorporating resistance into early-maturity soybean varieties and allow different types of host-plant resistance to be pyramided into varieties for growers.