Earliness Improvement Through Molecular Backcross Breeding Approach in Corn.

Corn (Zea mays L. ssp. Mays) is one of the most economically important monocot food crops worldwide. Development of high yielding varieties with desirable traits and allele combinations in a short time span is an important breeding objective in many programs. Trait introgression through backcross breeding has been a common method to incorporate one or a few genes from a donor into adapted varieties that are used in plant breeding for nearly a century but it is time consuming. However, use of Marker Assisted Selection (MAS) expedites the recovery of more than 99 % recurrent parent percent (RPP) in just three backcross generations, indicating that use of molecular markers increases the efficiency of introgressing the trait of interest. To meet the increased demands of the growing market, corn acres have expanded into the northern great plains of the United States. These regions were previously planted with cool season cereal crops such as wheat and barley. Corn grown in these “non-traditional” areas faces a much cooler and shorter growing season than corn grown across the traditional US Corn Belt. Therefore, the need arises to develop early maturing corn hybrids and parent lines that will mature and yield in these cooler and shorter growing regions. Our goal is to introgress donor segments from early lines into high yielding elite lines through marker assisted backcross breeding. At Dow AgroSciences, we have made significant progress in converting a few late maturing lines by optimizing population size, collecting appropriate phenotypic parameters and making selections by comparing SNP marker and phenotypic data.  This approach aid in recovering high percentage of the recurrent parental genome which is associated with yield components while retaining donor segments associated with earliness. The results are discussed in the poster.