Registration of Three Soybean Germplasm Lines Resistant to Phakopsora pachyrhizi (Soybean Rust)

Soybean rust, caused by Phakopsora pachyrhizi Sydow, is one of the most important foliar diseases of soybean [Glycine max (L.) Merr.]. Development of rust-resistant lines is one objective of many soybean breeding programs. Three soybean germplasm lines designated as TGx 1987-76F (Reg. No. GP-369, PI 657702), TGx 1987-118F (Reg. No. GP-370, PI 657703), and TGx 1987-129F (Reg. No. GP-368, PI 657701) with resistance to P. pachyrhizi and to Xanthomonas axonopodis pv. glycines (Nakano) Vauterin, Hoste, Kersters & Swings (bacterial pustule) were selected from lines developed by the International Institute of Tropical Agriculture (IITA) in collaboration with the USDA-ARS at the University of Illinois. These lines were derived from a tropical soybean rust-resistant cultivar UG5, and a rust-susceptible, high-yielding elite breeding line, TGx 1805-31F. A total of 297 F-7 lines were evaluated for rust resistance under greenhouse conditions using whole inoculated plants, in the laboratory using detached leaves, and under field conditions in Nigeria and Alabama (287 lines). Based on assessments from these various tests, these three lines have combinations of high levels of rust and bacterial pustule resistance, good agronomic traits, and adaptable maturity to the southern U.S. soybean breeding programs. Breeders will find the three lines useful as rust-resistant parental material in rust-prone areas.