Molecular Characterization and field evaluation of glyphosate tolerant sugacane: one step towards commercial release

NOGUERA, ENRIQUE, OSTENGO, PERERA, RACEDO, COSTILLA, ZOSSI, CUENYA, FILIPPONE, WELIN Y CASTAGNARO

Congreso; 11th germoplasm and breeding- 8th Molecular Biology Workshop ISSCT; 2015

Sugarcane commercial variety RA 87-3 was transformed with a genetic construct harbouring theepsps gene from Agrobacterium strain CP4 conferring tolerance to glyphosate and nptII gene forkanamycin-selection. Herbicide-tolerance of transformed lines was evaluated at differentconcentrations of glyphosate in the greenhouse. All herbicide-tolerant (HT) lines were field testedto confirm glyphosate-tolerance and perform preliminary evaluations of phenotypic resemblance toparental cultivar. All field-tested transformed lines maintained herbicide-tolerance but manyshowed phenotypic changes and/or growth aberrations. Ten HT-lines, showing close growthresemblance to RA 87-3, were analyzed using nine compulsory morphologic markers proposed bythe International Union for the Protection of New Varieties of Plants (UPOV) and 339 molecularmarkers. Out of the ten HT-lines tested, six showed minor morphologic and genetic variations andwere selected for field-testing over two vegetative crop cycles (plant-cane and first ratoon) at twoproduction areas in Argentina. The six field-tested HT-lines were found to be almostindistinguishable when comparing agronomic and industrial characteristics, antinutrients content(dhurrin) and chemical composition. Stable heritance of the CP4 epsps gene and glyphosatetolerancethroughout different clonal generations were confirmed by RT-qPCR and Southern blot.Flanking sequences to inserts in the genome of a candidate line were determined by using TargetedSequence Enrichment and Next Generation sequencing (NGS) technologies. Taking into accountall results, one out of the six lines tested was selected for a possible commercial release. Our studyconfirms the utility of genetic transformation as a complementary tool to classical breedingprocedures and highlights the usefulness of UPOV traits together with molecular markers for earlyselections of transgenic events that closely resemble their parental genotype.