Iron was resupplied to tobacco that was severely iron-deficient and the chloroplasts investigated for chlorophyll, iron content, photochemical, and development aberrations and photosystem components. Ferredoxin was purified from normal and iron deficient tobacco leaves. Lower ferredoxin and chlorophyll content in iron-deficient leaves were found compared to normal leaves. The ferredoxin from normal and iron-deficient leaves had the same molecular weight as spinach ferredoxin (Sigma Chemical Co.) and shared a similar antigenic property.Photosystem I (PSI) acti vity increased by about 100% during the first 10 days of regreening on a leaf surface area comparison. Only small increases in activity were found with PSII. Purified PSI particles were spectrophotometrically examined for any changes in P700, chlorophyll, cytochrome and protein components on a leaf area basis. With greening the individual components increased but the ratios remained constant. There were 6 polypeptide bands in the PSI particles when examined by electrophoresis. All bands stained with equal intensity with coomassie blue except for the ISkD band at day 0 of greening. Data suggest that iron stress is involved in the regulation of PSI development, possibly by the direct regulation of a low-molecular weight protein required for system assembly. Discussion is presented suggesting this protein is ferredoxin and that limitation of this component would directly affect chlorophyll biosynthesis and chloroplast structure.
Species in the families Amaranthaceae, Aizoaceae, Chenopodiaceae, Convolvulaceae, Euphorbiaceae, Nyctaginaceae, Portulacaceae, and Zygophyllaceae were examined for leaf anatomy typical of plants having the C4 type photosynthetic carbon fixation pathway. They are assembled by families into three groups: genera in which all species possess the specialization; genera in which some but not all species possess the specialization; and genera in which no species possess the specialization. The specialization in leaf anatomy was noted in species of 24 genera. Its presence is highly correlated with a habitat of limited water availability and (or) with a tropical origin. The carbon dioxide compensation points of nine species in the Chenopodiaceae family were measured. Low values were obtained only for those species that possess a form of specialized leaf anatomy (Atriplex confertifolia (Torr. & Frem.) Wats., A. falcata (M. E. Jones) Standl., Halogeton glomeratus (Bieb.) Meyer, Salsola kali L. var. tenuiflora Tausch.). The latter two species, having centric leaves, do not possess the more typical differential bundle sheath chlorenchyma but do possess two, individually distinct, single-cell layers of chlorenchyma, adjacent and external to the peripheral veins.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.