|JUMBO, M - University Of Delaware|
|WELDEKIDAN, T - University Of Delaware|
|Holland, Jim - Jim|
|HAWK, J - University Of Delaware|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2011
Publication Date: 7/1/2011
Citation: Jumbo, M., Weldekidan, T., Holland, J.B., Hawk, J. 2011. Comparison of Conventional, Modified Single Seed Descent, and Doubled Haploid Breeding Methods for Maize Inbred Line Development Using GEM Breeding Crosses. Crop Science. 51:1534-1543.
Interpretive Summary: The genetic base of commercial corn in the USA is narrow, most hybrids are related to each other. The USDA Germplasm Enhancement of Maize (GEM) project aims to increase the genetic diversity of the US corn crop by identifying useful breeding materials that are exotic (not closely related to US corn) and adapting them to US corn growing conditions. Diversifying the genetic base will help protect against uniform vulnerability to emerging diseases and will provide new genes for yield improvement. This study asked the question: which plant breeding method is best for developing high yielding hybrids from crosses between elite US corn inbreds and exotic corn? We obtained three such crosses from the GEM program and used four different breeding methods to make new inbred lines from them. We then crossed the new inbred lines to unrelated US lines to make new hybrids that were tested for yield and agronomic performance across numerous field sites. We found that there was little difference in the outcome due to the breeding method used. Therefore, we suggest that breeders use the easiest and fastest method available to develop inbreds from GEM crosses.
Technical Abstract: Breeding crosses from the Germplasm Enhancement of Maize (GEM) project between exotic accessions and elite Corn Belt Dent inbreds provide a unique opportunity for broadening the genetic base of the United States maize crop by incorporating favorable exotic alleles in elite genetic backgrounds. Genetic gains in the GEM program could be enhanced by identifying more efficient breeding procedures for this purpose. We compared four breeding methods, conventional GEM (CG), conventional mass (CM), modified single seed descent (MSSD), and doubled haploid (DH) methods, for their relative capacity to produce superior maize inbred lines and hybrids from three GEM breeding crosses, (ANTIG01xN16)xDE4, (AR16035xS02)xS09, and (DKXL212xS09)xS43b. Testcross evaluations of 50 selected lines from each combination of cross and breeding method were conducted across multiple environments, generally revealing no differences among breeding methods. The MSSD and CM methods had higher proportions of the top ten lines for grain yield and yield/moisture in the second year testcross re-evaluations of about the top 30% of lines. Hybrids from MSSD lines tended to have higher grain moisture, but MSSD hybrids with high yield/moisture could still be identified. The MSSD method may be an effective and efficient alternative to both pedigree and DH methods for developing high performing lines from the GEM breeding crosses as it requires relatively fewer resources.