Resumo

RACEDO, Josefina et al. Development of a further transgenic sugarcane cultivar resistant to glyphosate herbicide. Rev. ind. agric. Tucumán [online]. 2019, vol.96, n.2, pp.59-63. ISSN 1851-3018.

A previous development of transgenic glyphosate-resistant sugarcane suitable for commercial release was carried out through genetic transformation of cultivar RA 87-3. During the time elapsed to develop this technology, new commercial cultivars produced by the local breeding program have been adopted by farmers. The complex genetics of modern sugarcane cultivars, which are interspecific hybrids, highly polyploid and frequently aneuploid, make the introgression by backcrossing of the transgene into other varieties extremely difficult. Direct transformation of new commercial cultivars or promising clones at final stages of a breeding scheme could greatly improve the development and adoption of transgenic sugarcane by both farmers and millers. The aim of this study was to obtain glyphosate-resistant transgenic events of the two recently released cultivars, TUC 95- 10 and TUC 03-12, through the introduction via microprojectile bombardment of plasmids harbouring the epsps and nptII genes. A total of 23 and 8 independent bombardments experiments were carried out on TUC 95-10 and TUC 03-12, respectively. The stable transformation and integration of both epsps and nptII genes were determined by using PCR with specific primers. Transgenic events were evaluated for glyphosate tolerance under ex vitro conditions and for genetic similarity with donor plant by using target region amplification polymorphism (TRAP) molecular markers. Although plantlets of both varieties regenerated from calli, TUC 95-10 showed a low tissue culture-response since only two events were obtained, whilst a total of 22 plantlets regenerated for TUC 03-12. One line of TUC 95-10 and three lines of TUC 03-12 were PCR-positive for both genes and different levels of herbicide-tolerance were observed. Genetic analyses of 213 TRAP loci from transgenic lines derived from TUC 03-12 indicate that two events show 99.30% of similarity with the non-transformed TUC 03-12 control and the third had 98.7% similarity. These are encouraging results as, based on our previous experience, the molecular-marker data suggest that the events are practically identical to their parental cultivar, and are suitable for future comparative field testing.

Palavras-chave : Genetic transformation; biolistic; genetically modified organism; sugarcane; glyphosate.