Herbicide resistant transgenic sugarcane plants containing the bar gene

We have obtained herbicide resistant transgenic sugarcane plants (Saccharum spp. hybrids) of the commercial cultivar NCo 310. A particle inflow gun was used to bombard embryogenic calli obtained from immature inflorescences with microprojectiles coated with a plasmid containing the coding region of the bar gene fused to the maize ubiquitin-1 (Ubi-1) promoter, first exon, and first intron. Shoots were regenerated from calli selected for resistance to bialaphos (1 mg/L), and rooted on herbicide-containing medium (3 mg/L). Plants regenerated on selective media were screened for the presence of the bar gene by polymerase chain reaction. Northern blot analysis showed that transgenics were producing chimeric transcripts of the proper size. Most of the transformants examined displayed resistance to the commercial herbicide Ignite applied either to leaf segments or to the entire plant at dosages lethal to nontransformed controls. Southern blot analysis confirmed stable integration of three to 10 copies of the transgene into the sugarcane genome. A well-characterized transformant was submitted to three rounds of vegetative propagation, as well as through meristem culture. All resulting propagated clones displayed herbicide resistance comparable to the original transformant. The above results demonstrate that the bar gene can be an effective selectable marker in sugarcane transformation studies.