USING MOLECULAR MAKETS TO INTROGRESS TRAITS FROM RELATED WILD SPECIES INTO SUGARCANE

MOLECULAR markers could potentially increase the efficiency of introgression breeding in sugarcane. The implementation of markers within a breeding program will depend on the degree of repeatability of marker effects between different populations. We present work here designed to determine the best strategies for marker assisted breeding in sugarcane. Markers have been identified that are associated with sucrose accumulation in an introgression population (I1) generated from a cross between a S. officinarum (IJ76-514) and a commercial sugarcane variety (Q165A). Two progeny from this population were crossed with another two commercial varieties to generate two I2 populations. These were used to test whether the markers associated with sucrose accumulation identified in the I1 population were still present in the I2 generation. Forty Amplified Fragment Length Polymorphism (AFLP) primer combinations and 25 microsatellite primers were used to generate 3646 markers across both populations. Genetic maps were generated for the four parents of the two I2 populations and single factor analysis was carried out to identify markers associated with sucrose accumulation. In total, 13 markers associated with sucrose accumulation located on four of the eight homology groups (HG) were compared across the three populations. From three to 10 of the markers identified in the I1 population associated with sucrose accumulation were again identified in at least one of the I1 clones. All of the 13 markers were detected again in one of the parents of the two I2 populations. These results indicate that marker trait associations can be identified across generations and genetic backgrounds. This suggests that QTL mapping in introgression breeding programs may be done in early generations, and results used in subsequent backcrossing cycles.