Sugarcane is known for its highly complex genetics and more knowledge is needed for better use and conservation of genetic materials. In order to identify genotypes and to assess genetic diversity, diverse data sets such as morphological and molecular markers are used as a general approach. To evaluate the usefulness of different markers, important sugarcane genotypes in Argentina were characterized by AFLP, SSR and morphological traits. All genotypes characterized were grouped in one main cluster in dendrograms using two independent softwares. Interestingly, local genotypes grouped together with USA varieties and no clear genetic differentiation could be found probably due to intensive germplasm exchange between these breeding programs. The molecular markers tested were useful for genetic diversity assessment as well as for genotype identification. These markers should be included in the internationally established characters for sugarcane variety protection as they give a better view on whole genome complexity. Additionally, genetic similarities obtained from molecular markers will provide more accurate information to breeders than the pedigree method, especially when considering the asymmetric genetic inheritance of sugarcane. Morphological traits are valuable tools to identify genotypes since they reflect external resemblance more than genetic relatedness. When they were combined with molecular markers the dendogram obtained revealed genetic relationships and the genetic diversity was better estimated. In summary, both methods appear to be useful, complementing each other and should be used together to assist sugarcane breeders in estimating genetic diversity, electing parents for crossings, identifying superior lines and to protect intellectual property rights.

Sugarcane commercial variety RA 87-3 was transformed with a genetic construct harboring the epsps gene from Agrobacterium strain CP4 conferring tolerance to glyphosate and nptII gene for kanamycin selection. Transformed lines were multiplied in greenhouse, and herbicide tolerance was evaluated using different concentrations (3, 4, 8 and 16 l/ha) of glyphosate (Helm 48 % p/v). All herbicidetolerant (HT) lines were field tested to confirm glyphosate tolerance and perform preliminary evaluations of phenotypic resemblance to parental cultivar. All transformed lines maintained herbicide tolerance, but many showed phenotypic changes and/or growth aberrations. Ten HT lines, showing close growth resemblance to RA 87-3, were analyzed using nine compulsory morphologic markers proposed by the International Union for the Protection of New Varieties of Plants (UPOV) and 339 molecular markers. Out of the ten HT lines tested, six showed minor morphologic and genetic variations and were selected for field testing over two vegetative crop cycles (plant cane and first ratoon) at two production areas in Argentina. The six field-tested HT lines were found to be almost indistinguishable when comparing agronomic and industrial characteristics and chemical composition. Stable heritance of the CP4 epsps gene and glyphosate tolerance throughout different clonal generations were confirmed by RT-qPCR and Southern blot. Taking into account all results, two out of the six lines tested were selected for a possible commercial release. Our study confirms the utility of genetic transformation as a complementary tool to classical breeding procedures and highlights the usefulness of UPOV traits together with molecular markers for early selections of transgenic events that closely resemble their parental genotype.