Altering Chloroplast Size in Sugarcane By RNAi Suppression of FtsZ, Is Bigger Better?

Sugarcane is one of the most productive biofuel crops due to its superior photosynthetic efficiency. Sugarcane has a C4 type metabolism for fixation of carbon, allowing it to be very well adapted to biomass production in tropical and subtropical regions. Genetic improvement of photosynthetic efficiency could potentially be achieved by developing a photosynthetically more effective canopy. To evaluate the effect of chloroplast size on light penetration into the canopy and biomass production, we modified the expression of Filamenting temperature sensitive mutant Z (FtsZ). FtsZ is a key player in the division of both bacteria and chloroplasts. FtsZ is a cytoskeletal GTPase that self-assembles in vitro into filaments and other conformations similar to those formed by its eukaryotic structural homologue, tubulin. RNAi –suppression of the nuclear encoded FtsZ in sugarcane resulted in five-fold increase in chloroplast size. Field performance of transgenic plants will be reported.