Submitted to: Botanical Society of America Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 7/1/2003
Publication Date: 7/30/2003
Citation: EUBANKS, M.W., REYNOLDS, J.F., RIEDELL, W.E. A BRIDGING CROSS TO ENHANCE GENETIC DIVERSITY AND SUSTAINABILITY IN MAIZE. BOTANICAL SOCIETY OF AMERICA ABSTRACTS. 2003. Interpretive Summary:
Technical Abstract: Eastern gamagrass (Tripsacum dactyloides L.) is a relative of maize that has valuable genes for crop improvement and sustainability. This genetic resource has had limited usefulness in maize breeding programs due to sterility in maize-gamagrass hybrids. Crosses between gamagrass and teosinte, the closest wild relative of maize, have yielded fully fertile recombinants that are cross-fertile with maize and thus provide a genetic bridge to move Tripsacum genes into maize. This paper describes the gamagrass-teosinte genetic bridge, and reports on progress in a molecular-marker assisted, recurrent selection backcross breeding program focused on conferring protection against insect damage and drought tolerance in maize. Corn rootworm (Diabrotica virgifera LeConte), which is the worst insect pest of maize, is estimated to cost growers over $1.2 billion a year in crop loss and insecticide costs. The insecticides used to control this pest are among the most toxic to humans and the environment. Eastern gamagrass, which co-evolved with Diabrotica, has internal mechanisms that protect the plant from herbivory damage. Rootworm tolerant plants have been selected from insect bioassays that screened over 140 gamagrass-introgressed lines in a maize backcross breeding program. Artificially-infested field tests in South Dakota have confirmed natural rootworm tolerance is expressed in some of these Sun Dance Genetic lines. Gamagrass also has strong ability to withstand drought. Sun Dance Genetics hybrid families grown in summer nurseries have not required irrigation when typical maize crops in the same growing area have been lost to drought. This reduction in water requirement is being investigated and characterized in controlled environment growth chamber drought tests. Under these water deficit conditions the Sun Dance hybrids demonstrate better performance and have significantly higher grain yields than the corn controls.