Experts Review Applications of TALENs in Sugarcane

Experts from the University of Florida released a review article in The Plant Journal featuring the applications of RNA interference and various gene editing tools in sugarcane.

The complexity of sugarcane's genome has led to limited applications of site-specific nucleases, and with no reports about the use of meganucleases or zinc-finger nucleases. However, a pioneering study in 2016 used TALENs to target the lignin biosynthesis gene COMT, building on previous RNAi research demonstrating lignin reduction potential.

Two COMT variants (COMTa and COMTb) were identified in the CP88-1762 wild-type (WT) genotype. The researchers designed TALEN sites in a conserved region of the first exon using plant transformation methods that led to a total 66 transgenic lines. Mutation assessment showed that 99% of WT COMT sequences were converted to mutant versions, resulting in a 29–32% reduction in lignin content. They also noted that S lignin monomer content decreased while hemicellulose content increased.

The findings of the 2016 study were validated in a 2018 study, wherein 107 of 109 COMT copies were edited in the sugarcane line CB6. Similar biomass yield with non-modified sugarcane was recorded, as well as 19.5% lignin content reduction and a significantly altered S/G lignin monomer ratio, which boosted the biomass saccharification efficiency by 38%.

Another research in 2018 added insights to the previous findings. The researchers found that when combined with a recombinant xylose-utilizing yeast strain, bio-ethanol production increased by 148% compared to non-modified biomass. Even with a non-modified yeast strain, the edited biomass increased bio-ethanol production by 42%, providing additional evidence of the potential of engineering both feedstock and microorganisms to improve bioethanol yield from lignocellulosic biomass.

Read the open-access article in The Plant Journal.