Barley (Hordeum vulgare L. cvs Clipper, Procter, Astrix) seedlings were transferred from daylight to darkness and changes in chlorophyll a, chlorophyll b, protochlorophyllide and chlorophyllide (μ leaf−1) in either the first or second leaf determined spectrophotometrically after separating the esterified from unesterified pigments by partitioning between ammoniacal acetone and light petroleum ether. Chlorophyll a and b as well as protochlorophyllide accumulated in the dark. The ratio of chlorophyll to protochlorophyllide formed in the absence of light was 18:1. 5‐aminolevulinic acid (10 mM) promoted the synthesis of chlorophyll a and b and protochlorophyllide. Pigment synthesis and response to 5‐aminolevulinic acid addition was related to tissue age. Mature tissue in the apical third of the leaf accumulated most chlorophyll, but per μg chlorophyll present at the time of transfer to darkness, was less efficient than immature tissue towards the base of the leaf. Immature tissue was also most responsive to added 5‐aminolevulinic acid. Chlorophyll synthesis in the dark was accompanied by chloroplast development. Chloroplasts in immature leaf tissue increased in size and extent of thylakoid development when transferred from daylight to darkness. The results indicate that chlorophyll synthesis and chloroplast membrane development in light‐grown barley continue into the dark phase of the diurnal cycle. A light‐independent protochlorophyllide reductase in light‐grown barley seedlings is postulated.
|Number of pages||8|
|Publication status||Published - 1985|
- dark chlorophyll synthesis
- protochlorophyllide reduction