Acyl Lipids, Pigments, and Gramine in Developing Leaves of Barley and Its Virescens Mutant

Abstract

Changes in acyl lipids and pigments during the initial stages of chloroplast development in a virescens barley mutant (M) and the normal (N) were studied. Apical 3-cm leaf segments were extracted with chloroform-methanol, the extracts were purified on Sephadex G-25 columns and the polar lipids were separated on 2-dimensional TLC silica gel plates. The pigment remaining on the Sephadex column was identified as flavonoids and a zone on the TLC plates which did not correspond to the usual standards was identified as gramine. Quantification of acyl lipids by either polar head group analysis or fatty acid analysis using heptadecanoate as an internal standard gave similar results. The percent of the total lipid extract quantified for the M between 4 and 8 days ranged from 46-65% and that for the N ranged from 60-68%. Of these, acyl lipids represented 37-48% in the M and 43-50% in the N. By 8 days, mono- and digalactosyldiglyceride (MG and DG) accounted for 45 and 25% of the total acyl lipid of both the M and N. For the period of study here, this represented a 4-fold increase in MG and a 2.5-fold increase in DG in the M, but only a 1.8-fold increase for MG and DG in the N. These increases were closely correlated with the increases in chlorophyll. Chlorophyll increased sharply between 4 and 6 days for the N; in the M, it rose from 7-50% relative to the normal by 8 days. The proportions of the various fatty acids were unique for the lipid classes. The only major quantitative change for a fatty acid was for hexadecanoate in phosphatidylglycerol which increased from 5% at 4 days to 25-30% by 8 days. Relative to the N, the carotenoid content of the M increased from 14-50% between 4 and 8 days. In both the M and N, the increase in .beta.-carotene and chlorophyll were closely correlated.