Six barley chlorophyll (Chl) mutants, viridis, flavoviridis, chlorina, xanhta, lutea, and albina, differed in the contents of Chl (a+b) and carotenoids (Cars). In accordance with their Chl-deficient phenotype, the Chl a and b and Car contents of mutants decreased from viridis to albina, only xantha had the same or even higher concentration of Cars as the wild type plant. The albina mutant completely lacked and xantha had a significantly reduced photosynthetic activity. We found quantitative differences in protein contents between wild type and mutant plants, with the lowest concentration per fresh mass in the albina mutant. Chl fluorescence analysis revealed that heat-treated barley leaves of both the wild type and Chl mutants had a lower photosystem 2 efficiency than the untreated ones. With 35S-methionine labelling and SDS-PAGE we found that six to nine de novo synthetized proteins appeared after heat shock (2 h, 42 °C) in the wild type and Chl mutants. In albina the expression of heat shock proteins (HSPs) was reduced to 50 % of that in the wild type. Hence mainly albina mutants, with a completely destroyed proteosynthetic apparatus of the chloroplasts, are able to synthesize a small set of HSPs. The albina mutant is a very useful tool for the study of different gene expression of chloroplast and nuclear DNA. and E. Gálová, B. Böhmová, A. Ševčovičová.
Dark-grown seedlings of Pinus mugo Turra and Pinus sylvestris L. accumulate chlorophyll (Chl) and its precursor protochlorophyllide (Pchlide). Pchlide reduction is a key regulatory step in Chl biosynthesis. In the dark, Pchlide is reduced by light-independent Pchlide oxidoreductase (DPOR) encoded by three plastid genes chlL, chlN, and chlB (chlLNB). To investigate the differences in chlLNB gene expressions, we compared the dark-grown and 24-h illuminated seedlings of P. mugo and P. sylvestris. Expression of these genes was found constitutive in all analyzed samples. We report light-independent accumulation of important proteins involved in Chl biosynthesis (glutamyl-tRNA reductase) and photosystem formation (D1 and LHCI). Chl and Pchlide content and plastid ultrastructure studies were also performed. and K. Breznenová ... [et al.]