Growth Conditions and Ripening Influence Plastid and Microsomal Membrane Lipid Composition in Bell Pepper Fruit

Abstract

Plastids and microsomal membranes were isolated from pericarp tissue of mature-green and red-ripe bell pepper (Capsicum annuum L.) fruit harvested from greenhouse- and field-grown plants. The lipid composition of these membrane fractions changed much more with ripening of field-grown than greenhouse-grown fruit. Also, the phospholipid (PL), free sterol (FS), steryl glycoside (SG), and acylated steryl glycoside (ASG) content of microsomes and plastids from green and red fruit were very different under the two growing conditions. Total steryl lipids (TSL = FS + SG + ASG) and the TSL: PL ratio increased in microsomes and decreased in plastids with ripening. These changes were much greater in field-grown fruit. The ASG: SG ratio decreased with ripening in both membrane fractions under both growing conditions. Ripening and growth conditions affected the phospholipid and sterol composition in plastids much more than in microsomes. Lipid changes associated with the chloroplast to chromoplast transformation were similar in field- and greenhouse-grown fruit, including an increase in the galactolipid: PL ratio.