2011 Annual Report
1a.Objectives (from AD-416)
The long term objective of this project is to diversify the genetic base of maize in the United States by the addition of new genes from exotic maize that will improve agronomic productivity, disease resistance, and insect resistance, and contribute value-added grain characteristics, including total extractable starch to support ethanol production.
1b.Approach (from AD-416)
Manage GEM field nurseries, seed inventories, and germplasm exchange so that new sources of germplasm and information reach stakeholders annually. With the GEM Project Technical Steering Group (TSG), identify and acquire new sources of exotic maize germplasm for breeding and diversity assessment projects. Conduct cooperative maize germplasm evaluations for host-plant resistance to gray leaf spot, southern corn leaf blight, northern leaf blight, and fumonisin production. Develop advanced maize breeding families, derived from non-U.S. and U.S. sources which are selected for wide adaptation to U.S. conditions.
Approximately 1,000 entries were advanced in the breeding nursery this summer, and over 500 new hybrids were developed for evaluation in 2012. Sixty entries (of 250 tested) were advanced to second year trials, and twenty-two entries (of forty-seven tested) were advanced to third year trials. In 2011, over 11,000 yield trial plots were coordinated through Raleigh, with approximately 6,000 of those plots planted at NC State and/or NC Dept. of Agriculture locations and the rest with germplasm enhancement of maize (GEM) cooperators. Approximately 3200 GEM nursery rows and 1250 isolation rows were planted in summer 2011 at Raleigh, and 800 nursery rows were grown in the previous winter in Homestead, FL. Nursery work involves four new GEM breeding crosses, while seventy-five breeding crosses were observed for agronomic traits of interest and 130 were included in yield trials to prioritize further utilization. Disease evaluation continues in 2010 for Gray leaf spot, where advanced materials are evaluated at three locations in North Carolina. Also, we have continued routine screening of available tropical inbred lines, as so little data are available to choose among them for use in GEM or other research.
Over 800 nursery rows in Raleigh are devoted to further increasing the genetic diversity in maize through identification of useful alleles in exotic germplasm, which involves accessions that are outside the core plant breeding materials utilized by GEM and most plant breeding organizations. These accessions may contain valuable alleles of interest to breeders that would otherwise not be utilized due to the difficulties in growing tropical germplasm per se in the Corn Belt. The new crosses represent about 250 accessions. The initial steps of the project are coordinated from Raleigh, and the latter steps through Ames, IA. The crosses were produced last winter in Homestead, FL by this project and in previous years in Hawaii and in Puerto Rico by GEM cooperators using two off-patent maize inbreds. Backcrosses to the two off-patent maize inbreds were made this summer in Raleigh while the germplasm produced in Raleigh last summer has been planted by GEM coordinator in Ames, IA and by GEM cooperators at two locations in Illinois.
Evaluated and recommended exotic and semi-exotic germplasm sources. Genetic diversity in U.S. maize breeding programs is limited by use of a very limited base of maize germplasm that is derived primarily from the race “Corn Belt Dent”, only one of the 200-300 recognized races of maize. ARS researchers in Raleigh, N.C. evaluated a large number of exotic maize inbreds and recommended several as promising sources of genetic diversity for breeding programs. Germplasm recommended over the past eight years by the germplasm enhancement of maize (GEM) projects in Raleigh and Ames, IA (almost 200 families) was evaluated in head-to-head trials to facilitate the incorporation of GEM germplasm into breeding programs by allowing breeders to select the most promising families.