Enhancement of biomass production and cell wall degradability by AtGA20ox1 overexpression and Bd4CL1 downregulation

Food and feed have always originated mainly from plants, but they can now also supply energy in the form of biofuel. The supply will be under great strain, however, from the combination of a rapidly increasing population, higher living standards in developing countries, and environmental changes. Additionally, future agriculture will have to meet the needs of a low-carbon economy. For all of these reasons, the next generation of crops will need to exhibit increased yield and quality. When using whole plant as energy source, such as for animal feed and bio-ethanol feedstock, more biomass and a higher glucose release from cell walls will also be required.
This presentation describes a proof of concept to improve cell wall degradability or digestibility as well as biomass production through transformation and mutagenesis in Brachypodium Bd21-3 plants.
Our focus lies on altering the lignin content, as this is often related to improved cell wall degradability. The Brachypodium Bd21-3 TILLING population of INRA Versailles was screened for mutants in the 4-coumarate ligase (4CL) gene. Fourteen mutations were identified and plants will be scored for glucose release upon enzymatic hydrolysis.
Lignin mutants can show improved degradability, but these lines often exhibit a lower yield. An increase in biomass production can be achieved by overexpressing genes (e.g. GA20ox1 in Arabidopsis) that are known to enhance organ size (leaf and stem). We currently have 18 UBIL::AtGA20ox1 lines in the Bd21-3 inbred line. Expression levels are now being analyzed. Promising lines will be phenotyped for enhanced biomass production.
Ultimately, we will seek to combine the improved properties of cell wall degradability or digestibility and biomass production by either transforming the plants in a mutant background or crossing transformed lines.