GENETIC-ANALYSIS OF AGRONOMIC TRAITS IN A CROSS BETWEEN SUGARCANE (SACCHARUM-OFFICINARUM L) AND ITS PRESUMED PROGENITOR (S-ROBUSTUM BRANDESAND JESW EX GRASSL)

Saccharum robustum Brandes & Jesw. ex Grassl has been suggested as the immediate progenitor species of cultivated sugarcane (S. officinarum L.) [4]. Chromosome pairing and assortment in these two species were p reviously studied by genetic analysis of single-dose DNA markers in pa rents in and 44 F-1 progeny of a cross between euploid, meiotically re gular 2n = 80 S. officinarum 'LA Purple' and S. robustum 'Mol 5829' [2 ]. This same population was subsequently clonally propagated and evalu ated in replicated trials for quantitative traits important to sugarca ne breeders. Numbers of stalks, tasseled stalks, and stalks with smut, and the average diameter of two stalks were determined one day prior to harvest. At harvest, plant material from each plot was weighed and evaluated for pol (sucrose content) and fiber percentages. Clones were significantly different (P<0.01) for all traits analyzed. Association s of 83 single-dose arbitrarily primed PCR genetic markers with quanti tative trait loci (QTL) of recorded traits was determined by single-fa ctor ANOVA, and multiple regression. QTL analysis revealed markers sig nificantly (P<0.05) associated with the expression of each trait analy zed. Markers associated with regression were tested for digenic linear x linear epistatic interactions. The various multilocus models explai ned between 23% and 58% of the total phenotypic variation and 32% and 76% of the genotypic variation for the various traits. Digenic interac tions were uncommon. Implications for marker-assisted selection in sug arcane and sugarcane domestication are discussed.