Markers can increase selection efficiencies when breeding for disease resistance. The number of resistance genes for simply inherited wheat diseases mapped with markers is increasing on a monthly basis. However, their adoption in breeding programs is often slowed by the cost of this technology in terms of labol; equipment, and supplies. One widely used disease resistance marker is the endopeptidase isozyme that is linked with eyespot resistance derived from Aegilops ventricosum. This marker is widely used to introgress this chromosome segment into winter wheat in the Pacific Northwest of the U. S. Another use of markers in disease resistance is expected to arise from those diseases that are quantitatively inherited, but are difficult to screen for using conventional methods [e.g. Fusarium head blight (FHB) and tanspot]. FHB resistance genes have been mapped with the intent of using the markers in selection. Two populations were analyzed, resulting in the identification of six quantitative trait loci (QTL) associated with resistance. One QTL on chromosome 3BS explained more than 15% of the variation for FHB resistance in both populations, and two other QTL also were identified in both populations. PCR markers are being developed for two of these QTL to facilitate their introgression in adapted germplasm. Two major genes are largely responsible for tan spot resistance. One gene on 5BL conditions resistance to tan necrosis, and a QTL on 1AS in combination with other minor genes conditions resistance to chlorosis. Selection based on these two genes alone provides a high level of resistance to this disease.

English

0105|AL-Wheat Program|AGRIS 0102

Jose Juan Caballero

CIMMYT Publications Collection