A photorespiratory bypass increases plant growth and seed yield in biofuel crop Camelina sativa.

Camelina sativa is an oilseed crop with great potential for biofuel production on marginal land. The seed oil from camelina has been converted to jet fuel and improved fuel efficiency in commercial and military test flights. Hydrogenation-derived renewable diesel from camelina is environmentally superior to that from canola due to lower agricultural inputs， and the seed meal is FDA approved for animal consumption. However， relatively low yield makes its farming less profitable. Our study is aimed at increasing camelina seed yield by reducing carbon loss from photorespiration via a photorespiratory bypass. Genes encoding three enzymes of the Escherichia coli glycolate catabolic pathway were introduced: glycolate dehydrogenase (GDH)， glyoxylate carboxyligase (GCL) and tartronic semialdehyde reductase (TSR). These enzymes compete for the photorespiratory substrate， glycolate， convert it to glycerate within the chloroplasts， and reduce photorespiration. As a by-product of the reaction， CO2 is released in the chloroplast， which increases photosynthesis. Camelina plants were transformed with either partial bypass (GDH)， or full bypass (GDH， GCL and TSR) genes. Transgenic plants were evaluated for physiological and metabolic traits.