Molecular characterization and field evaluation of glyphosate tolerant sugarcane: a step towards commercial release

NOGUERA, A., ENRIQUE, R., OSTENGO, S., PERERA, M.F., RACEDO, J., COSTILLA, D., ZOSSI, S., CUENYA, M.I., FILIPPONE, M.P., WELIN, B. AND CASTAGNARO, A.P..

Workshop; 8th Molecular Biology Workshop ISSCT (International Society of Sugar Cane Technologist); 2015

Sugarcane commercial variety RA 87-3 was transformed with a geneticconstruct harbouring the epsps genefrom Agrobacterium strain CP4conferring tolerance to glyphosate and nptIIgene for kanamycin-selection. Herbicide-tolerance of transformed lines was evaluatedat different concentrations of glyphosate in the greenhouse. Allherbicide-tolerant (HT) lines were field tested to confirm glyphosate-toleranceand perform preliminary evaluations of phenotypic resemblance to parentalcultivar. All field-tested transformed lines maintained herbicide-tolerance butmany showed phenotypic changes and/or growth aberrations. Ten HT-lines, showingclose growth resemblance to RA 87-3, were analyzed using nine compulsorymorphologic markers proposed by the International Union for the Protection ofNew Varieties of Plants (UPOV) and 339 molecular markers. Out of the tenHT-lines tested, six showed minor morphologic and genetic variations and wereselected for field-testing over two vegetative crop cycles (plant-cane andfirst ratoon) at two production areas in Argentina. The six field-testedHT-lines were found to be almost indistinguishable when comparing agronomic andindustrial characteristics, antinutrients content (dhurrin) and chemicalcomposition. Stable heritance of the CP4 epspsgene and glyphosate-tolerance throughout different clonal generations wereconfirmed by RT-qPCR and Southern blot. Flanking sequences to inserts in thegenome of a candidate line were determined by using Targeted SequenceEnrichment and Next Generation sequencing (NGS) technologies. Taking intoaccount all results, one out of the six lines tested was selected for apossible commercial release. Our study confirms the utility of genetictransformation as a complementary tool to classical breeding procedures andhighlights the usefulness of UPOV traits together with molecular markers forearly selections of transgenic events that closely resemble their parentalgenotype.