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

NOGUERA, A.; ENRIQUE, RAMÓN; OSTENGO, S.; PERERA, M.F.; COSTILLA, D.; RACEDO, J.; CUENYA, M. I.; WELIN, B.; CASTAGNARO, ATILIO

Workshop; ISSCT 11th GERMPLASM AND BREEDING WORKSHOP/ 8th MOLECULAR BIOLOGY WORKSHOP 2015; 2015

ISSCT

Sugarcane commercialvariety RA 87-3 was transformed with a genetic construct harbouring the epsps gene from Agrobacteriumstrain CP4 conferring tolerance to glyphosate and nptII gene for kanamycin-selection. Herbicide-tolerance of transformedlines was evaluated at different concentrations of glyphosate in the greenhouse.All herbicide-tolerant (HT) lines were field tested to confirmglyphosate-tolerance and perform preliminary evaluations of phenotypicresemblance to parental cultivar. All field-tested transformed lines maintainedherbicide-tolerance but many showed phenotypic changes and/or growthaberrations. Ten HT-lines, showing close growth resemblance to RA 87-3, wereanalyzed using nine compulsory morphologic markers proposed by theInternational Union for the Protection of New Varieties of Plants (UPOV) and339 molecular markers. Out of the ten HT-lines tested, six showed minormorphologic and genetic variations and were selected for field-testing over twovegetative crop cycles (plant-cane and first ratoon) at two production areas inArgentina. 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 ofthe CP4 epsps gene andglyphosate-tolerance throughout different clonal generations were confirmed byRT-qPCR and Southern blot. Flanking sequences to inserts in the genome of acandidate line were determined by using Targeted Sequence Enrichment and NextGeneration sequencing (NGS) technologies. Taking into account all results, oneout of the six lines tested was selected for a possible commercial release. Ourstudy confirms the utility of genetic transformation as a complementary tool toclassical breeding procedures and highlights the usefulness of UPOV traitstogether with molecular markers for early selections of transgenic events thatclosely resemble their parental genotype.