The disappearance kinetics of Lhcb polypeptides during dark-induced senescence of leaves

Abstract

A set of polyclonal antibodies in conjunction with immunoblot technique and integrating densitometry has been used to positively identify and quantify Lhcb 1-6 polypeptides in barley (Hordeum vulgare L.) leaves in which senescence processes were induced by detachment and dark incubation for 0–6 d. A considerable hetero-geneity with regard to disappearance kinetics on a chlorophyll basis during the course of senescence has been foundamong individual Lhcbs. Lhcb 2/1 (the heavier of two polypeptides representing barley Lhcb2) and Lhcb3 exhibited the most rapid disappearance kinetics and decreased to 20 and 42% of their initial levels, respectively, after 6 d of dark incubation. Lhcb 1, 4 and 6 levels were maintained through the senescence, at a level very similar to that of fresh leaves, while Lhcb 2/2 (the lighter of two polypeptides representing barley Lhcb 2) and Lhcb 5 were the most stable of all Lhcbs — their relative abundance increased after 6 d of dark incubation of the leaves to 181 and 120%, respectively, of the value detected in fresh leaves.