Poster: Late and Moved Abstracts

Abs # 1408: Anionic lipids are essential for chloroplast structure and function

Presenter:	Yu, Bin , yubin@pilot.msu.edu
Authors	Yu, Bin  (A)   Benning, Christoph  (A)
Affiliations:	(A): Michigan State University

The chloroplast of plant cells contains two major anionic lipids, Sulfoquinovosyl diaylglycerol (SQDG) and phosphatidyl diacylglycerol (PG). Previously, it was proposed that SQDG can substitute PG to maintain a constant amount of anionic lipids during phosphate deprivation. Here we report the generation of an Arabidosis double mutant deficient in SQDG and reduced the amount of PG. Lipid analysis showed that the total content of anionic lipids was reduced to two thirds of wild-type in the double mutant. The double mutant had pale yellow cotyledons and leaves. The growth of the double mutants was compromised, although it was capable of autotrophic growth. In addition, the content of chlorophyll is reduced and the photosynthetic capacity was impaired in the double mutant. In vivo chlorophyll fluoresence measurement showed that the electron transfer was effected in the double mutant. DCMU treatment indicated that the electron transfer from QA to QB was blocked in the double mutant. Furthermore, the double mutant had altered leaf structure and a reduced number of mesophyll cells. The ultrastructure of chloroplast was also changed in the double mutant. These results suggested that the constant content of anionic lipids is required to maintain plant growth, chloroplast structure and function.