Research HighlightsProgress made in development of superior traits in Roundup Ready 2 yield soybeans
Southern Program Invests in Dynamic Research
Soybean breeders/geneticists at the University of Georgia, Drs. H. Roger Boerma and Zenglu Li, and the University of Tennessee (Dr. Vince Pantalone) have made progress toward development of Roundup Ready 2 Yield® (RR2Y) soybeans for the southern region with improved seed protein, low phytate, Asian soybean rust (ASR) resistance, or soybean cyst nematode (SCN) resistance. The RR2Y trait is a second generation glyphosate herbicide resistance technology developed by Monsanto and it is anticipated to improve production over the original Roundup Ready trait.
Improving seed protein is important because soybean meal demand is projected to increase by over 30% in the next 10 years. The soybean production regions in southern U.S. favor enhanced protein, providing farmers with the opportunity to produce high yielding soybeans for the high protein soy meal market. The low phytate trait will further improve soybean meal by enhancing poultry and swine nutrition. An additional benefit will be the reduction of phosphorous loads to the environment. Strategic breeding for ASR and SCN resistance protects the stability of the crop.
The University of Georgia team analyzed data from 2011 yield trials of 178 breeding lines with the original Roundup Ready trait and containing two important genes for resistance to ASR. The new GA soybean lines were also resistant to southern root-knot nematodes and race 3 of SCN. Genes are typically found in two alternative forms, known as alleles. In new material, based on a two-location mean, 41 RR2Y lines with alleles for ASR resistance and yielding greater than the commercial check varieties were selected for testing in 2012. Two multi-state experiments containing 68 GA RR2Y lines were also conducted. These lines contained both genes for resistance to ASR and are resistant to southern root-knot nematode and race 3 of SCN. In a cooperative test at 10 locations with private industry in 2010, the high yielding new GA RR2Y line, G09PR-54378 yielded 108.5 percent of the commercial Roundup Ready checks of similar maturity. This line yielded 104.9% of the test average in the 2011 GA statewide test at six locations, and it was one of top yielding soybean lines in the test.
In a second cooperative test containing six RR2Y experimental lines conducted at eight locations with private industry in 2011, the high yielding line, G10PR-56248R2 yielded a 8.2% advantage over commercial RR2Y soybean varieties. These new University of Georgia high yielding Roundup Ready 2 Yield soybean lines will be released in 2014 for production.
High protein and low phytate single nucleotide polymorphism (SNP) markers, representing single base pair changes in the genetic code, which were developed at the University of Georgia were analyzed on DNA extracted from F1 hybrid seed of the second backcross of G00-3212 and G00-3880 to lines containing the high protein QTL from Danbaekkong soybean and the low phytate QTLs from soybean CX1834-1-2. The ¾-seed chips of lines with the Danbaekkong allele for high protein and the CX1834-1-2 alleles for low phytate were planted in the greenhouse to provide a pollen source for the next cycle of backcrossing. The purpose is to pyramid the high protein and low phytate traits into RR2Y versions of G00-3213 and G00-3880. The third backcrosses to G00-3213 and G00-3880 have now been accomplished.
The University of Tennessee team analyzed data from advanced TN RR2Y lines in the 2011 Tennessee State Variety Test (seven environments). Results showed that the best new TN RR2Y lines yielded better than or equivalent to the average of all entries in each individual maturity test, indicating that commercially competitive material has rapidly been developed by the program. The most recent Roundup Ready variety released by the Tennessee Agricultural Experiment Station ranked at the top of the test for 2011, and it was also the top yielding MG V soybean for the two-year (2010-2011) and three-year (2009-2011) averages. On three-year average, it produced 33 five bushels/acre more yield than the average of commercial
That kind of yield advantage provides a potential revenue increase of over $50 per acre to producers at current commodity prices. The new variety shows strong field tolerance to sudden death syndrome (SDS) and excellent resistance to race 2 of SCN, which is rapidly becoming a prominent race in the Mid South, although resistant varieties are scarce for southern
In 2011 breeder tests at two to three testing locations, several new TN RR2Y lines show strong promise, including new high yielding MG V lines. Those lines were compared to commercial checks in field trials under irrigation to optimize yield potential. The Tennessee program submitted 10 advanced RR2Y lines to the 2012 USDA Southern Uniform Soybean Testing Program for evaluation in field trials throughout the region.
This included material in the MG V, and MG VI tests, as well as in earlier maturity groups. That collaborative regional test provides opportunities to compare advanced lines with high yielding checks and the best new lines currently available by public breeders.
The University of Tennessee team has collected DNA from field grown plants this summer for SNP analyses for low phytate, increased protein or ASR. The ability to use SNP markers to confirm gene transfer and select superior plants is a new approach that improves the program’s efficiency. Progeny from crosses targeting combining low phytate and improved protein to make greater than or equal to 48 percent protein soy meal in early to mid MG V RR2Y genetic backgrounds are being selected from SNP data this season. Likewise, RR2Y plant selections based on SNP marker inheritance of the Danbaekkong allele with increased protein are being accomplished.
Progeny that inherited the Hyuuga allele for ASR, include RR2Y crosses for high yield and greater than or equal to 48% protein soy meal in early MG V to early MG VI material.
The soybean breeding and genetics teams at the University of Georgia and the University of Tennessee have made important strides in improving soybean meal quality and plant disease resistance in high yielding Roundup Ready 2 Yield® soybeans well adapted to the southern region.
This research is currently being funded by the Southern Soybean Research Program.