Trehalose phosphate phosphatase overexpression for the mitigation of high-light induced stress in Parachlorella kessleri

Parachlorella kessleri is a marine algal species with diverse biofuels and pigments due to its high lipid content. P. kessleri undergo photo-inhibition when grown in outdoor cultivation due to high-light irradiance. Trehalose is a regulatory molecule to relieve stress conditions in P. kessleri. In the present study, over-expression of trehalose phosphate phosphatase (TPP), the trehalose pathway's second gene, was employed in P. kessleri to overcome high-light-induced photo-inhibition. TPP over-expression led to increased trehalose content by 27.23 %. Transformants exhibited enhanced H2O2 scavenging, reduction in chlorophyll b content and enhanced photo-synthetic efficiency (Y(II)) as well as regulated non-photochemical quenching (Y(NPQ)) as compared to that of wild type. These combined physiological changes resulted in 35 % and 15 % biomass productivity enhancement at 1000 and 1200 mu E m- 2 s- 1. TPP over-expression was thus associated with improved photosynthetic efficiency and high-light stress resistance in P. kessleri.