Trehalose phosphate synthase overexpression in Parachlorella kessleri improves growth and photosynthetic performance under high light conditions.

Parachlorella kessleri is a promising oil-bearing marine alga which shows decreased growth under high light stress. Osmolytes are known to relieve stress by protecting the cell membrane, proteins, and enzymes. Enhanced production of osmolyte (trehalose) was thus used to relieve stress in P. kessleri by overexpression of trehalose phosphate synthase (TPS) gene. Transformed P. kessleri was grown under different light regimes to study the effect of trehalose overproduction on growth. Study of one of the TPS transformants showed increased trehalose as well as increased biomass and decreased pigments, reactive oxygen species, and lipid peroxidation of cell membrane. The improved photosynthetic performance of the transformant was also signified by pulse-amplitude-modulated fluorometric analysis. All of these factors reveal improved stress tolerance under high light conditions by increased trehalose accumulation due to TPS overexpression in P. kessleri.