Date: 3/29/99

Time: 4:30

Type: Symposium

Number: 41

DNA marker-assisted selection of cereal aphid resistance genes: Improving the accuracy of their inclusion in wheat insect pest management

*C.M. Smith and M. Flinn, Department of Entomology, Kansas State University, Manhattan, KS 66506
Contact e-mail: msmith@oz.oznet.ksu.edu

DNA marker technology is being increasingly used as a tool for crop improvement to overcome some weaknesses of plant breeding based on morphological (phenotypic) characters. General advantages of DNA genotypic markers include their ability to reveal neutral sites of variation in DNA sequences, their greater number than phenotypic markers, and the fact that they have no disruptive effect on plant physiology. DNA markers have been used to identify the location of major plant genes for insect resistance in cowpea, rice, mungbean, barley, and wheat. Insect resistance genes identified in maize, potato, rice, and tomato have been shown to be linked in each to several minor genes, analyzed as quantitative trait loci. Thus, selection of plants based on DNA marker linkage before the phenotypic trait for resistance is expressed, holds promise for greatly accelerating the rate of development of arthropod resistant crop plants. In different studies, we have determined that a wheat sequence tagged site DNA marker located on the long arm of chromosome 7 in the A genome of wheat is linked to a gene from Agropyron elongatum (tall wheatgrass) which expresses resistance to biotype I of the greenbug (GB I), Schizaphis graminum (Rondani). We also have strong preliminary evidence that a gene for resistance to GB I in an Aegilops tauschii (goat grass) accession is linked to a wheat microsatellite DNA marker on the long arm of wheat chromosome 7 in the D genome. Data from genotypic and phenotypic evaluations of segregating plant populations will be presented to demonstrate how DNA marker-assisted selection is being used to increase the efficiency of wheat breeding for greenbug resistance, one of the goals of the KState Plant Resistance to Insects Laboratory.

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