Recent progress in understanding the origins of plastids from endosymbiotic cyanobacteria is reviewed. Establishing when during geological time the endosymbiosis occurred remains elusive, but progress has been made in defining the cyanobacterial lineage most closely related to plastids, and some mechanistic insight into the possible existence of cryptic endosymbioses perhaps involving Chlamydia...

The question whether sucrose (Suc) is present inside plastids has been long debated. Low Suc levels were reported to be present inside isolated chloroplasts, but these were argued to be artifacts of the isolation procedures used. We have introduced Suc-metabolizing enzymes in plastids and our experiments suggest substantial Suc entry into plastids. The enzyme levansucrase from Bacillus subtilis...

Chloroplasts of higher plants develop from proplastids, which are undifferentiated plastids that lack photosynthetic (thylakoid) membranes. In flowering plants, the proplastid-chloroplast transition takes place at the shoot apex, which consists of the shoot apical meristem (SAM) and the flanking leaf primordia. It has been believed that the SAM contains only proplastids and that these become ch...

Plastids in Nicotiana tabacum are normally transmitted to the progeny by the maternal parent only. However, low-frequency paternal plastid transmission has been reported in crosses involving parents with an alien cytoplasm. Our objective was to determine whether paternal plastids are transmitted in crosses between parents with the normal cytoplasm. The transplastomic father lines carried a spec...

In Hordeum vdgare, L., a strain known as "Okina-Mugi" shows variegation with white stripes on the green parts of the plant body. The genetics of the variegated barley was thoroughly studied by S8 (1921). The white stripes are due to the propagation of cells containing white plastids, which are produced by recurring exo-mutations of the green plastids. The strain carries a stimulating gene, by t...

The evolution of oxygenic photosynthesis by cyanobacteria was arguably one of the most significant biological events in Earth’s history, shaping the atmosphere and subsequently leading to diverse ecosystems (1). The permanent endosymbiotic merger between a cyanobacterium and a unicellular heterotrophic eukaryote in deep evolutionary time set the stage for the stunning diversity of photosyntheti...

While several aspects of primary metabolism are identical in plant and animal cells, others are distinctly different. The most prominent difference is the subcellular localization of biosynthetic reactions. Anabolism in animal and microbial cells takes place within the cytoplasm. Plant cells, however, have the anabolic reactions primarially localized within a double membrane-limited organelle, ...

Intact plastids from greening maize (Zea mays L.) leaves converted [(14)C]glutamate and [(14)C]2-ketoglutarate (KG) to [(14)C]5-aminolevulinic acid (ALA). Glutamate appeared to be the immediate precursor of ALA, while KG was first converted to glutamate, as shown by the effect of various inhibitors of amino acid metabolism. Plastids from greening leaves contained markedly higher activity as com...