Genetic Mapping of Molecular Markers Related to Fiber Production in Sugarcane

Sugarcane is one of the major economic crops around the world and is gaining attention because of its energetic potential. To increment productivity, molecular biology is useful to generate improved sugarcane varieties. We aim to build a genetic map with traits related to fiber content, using 250 individuals derived from a bi-parental cross between two elite clones from CTC’s (Centro de Tecnologia Canavieira) breeding program, in Brazil. Lignin and cellulose content analyses were performed at the plant cane stage, using Near Infrared. As preliminary results, 70 Expressed Sequence Tags Single Sequence Repeats (EST-SSR), obtained from the lignin and cellulose biochemical pathways, and 15 genomic Microsatellites (gSSR) were screened in the mapping population, producing 157 polymorphic markers. Only single dose markers were considered, in a total of 64. To allow preliminary analysis of marker-trait association without a genetic map, a Single-Marker Analysis for lignin and cellulose percent was performed by maximum likelihood tests in models considering one marker at a time.  Overall, 26 suggestive marker-trait associations were found at P<0.05, of which 13 markers with cellulose and 13 with lignin. Only EST-derived markers showed association with these traits, which is interesting because it illustrates the utility of EST-SSRs for mapping sugarcane genes (Da Silva, 2001). Ten markers (38%) were aligned to the sorghum genome and mapped in the chromosomes 1,2,4 and 7. There are evidences that, in sorghum, chromosome 1 is related to cellulose and chromosomes 2, 4 and 7 to hemicellulose content, thus confirming that SSRs, conserved in sugarcane and sorghum, would be very informative for mapping quantitative trait loci in sugarcane. These markers can be viewed as consistent markers, with potential to be applied in marker assisted selection.