Abstract
Monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) are the major lipids in chloroplasts. These galactoglycerolipids are known to play an important role apart from their involvement in chloroplast biogenesis and photoautotrophic growth. In Arabidopsis grown under Pi-limited conditions, an accumulation of DGDG occurs concomitantly with a decrease of phospholipids and expression of typeB MGD gene is increased. It is unknown whether this Pi starvation-induced lipid remodeling is common to plants. Here, we cloned two types of sesame MGDG synthase genes and analyzed the lipid composition and gene expression in Pi-starved sesame seedlings. As a result, we observed the accumulations of not only DGDG but MGDG in sesame roots under Pi starvation, while in Arabidopsis, only DGDG accumulates. MGD gene expressions were similar between sesames and Arabidopsis. Hence, we concluded that sesames also have the lipid remodeling, but it is distinct from Arabidopsis one in respect of MGDG accumulation.
