The rbcS gene coding for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) of the brown alga Pylaiella littoralis is located within the plastid genome and is transcribed as a single polycistronic mRNA with the gene for the large subunit of Rubisco, rbcL. The structure of the Rubisco operon from P. littoralis was determined. Molecular phylogenies for rbcS and rbcL with a wide range of prokaryotes and eukaryotes were constructed which are congruent with recent evidence for polyphyletic plastid origins. Both rbcL and rbcS of the beta-purple bacterium Alcaligenes eutrophus clearly cluster with the rhodophyte and chromophyte proteins. The data suggest that the Rubisco operons of red algal and chromophytic plastids derive from beta-purple eubacterial antecedents, rather than the cyanobacterial lineage of eubacteria from which other of their genes derive. This implies a lateral transfer of Rubisco genes from beta-purple eubacterial ancestors to the cyanobacterial ancestor of rhodophyte and chromophyte plastids.

The psaB gene codes for one of two highly conserved P700 chlorophyll a apoproteins of photosystem I. This gene was cloned from the brown alga, Pylaiella littoralis (L.) Kjellm., and its primary sequence was determined. The inferred amino acid sequence of the P. littoralis protein was compared to homologous sequences from land plants, green algae, and a cyanobacterium. The psaB protein sequence is very conserved in all the examined taxa, and an unrooted phylogenetic tree, generated from a distance matrix, shows that the P. littoralis gene is closer to that of the cyanobacterium Synechocossus sp. PCC 7002 than are those of green algae, land plants, and Euglena gracilis.

The diversity of 51 representative populations of the 5 Aegilops species from Moroccan collection was analyzed using 22 RAPD primers. We investigated the associations among these 5 Aegilops species (A. geniculata Roth (UUMM), A. triuncialis L. (UUCC), A. ventricosa Tausch (DDNN), A. peregrina (Hackel) Maire et Weiller (UUMM) and A. neglecta Req. ex Bert. subsp. recta (Zhuk.) K.Hammer (UUMMNN)); some diploid species considered as their ancestors; accessions of some neighboring countries and also accessions of Triticums. A total of 650 polymorphic RAPD fragments were amplified. A dendrogram was constructed using the un-weighed pair group method arithmetic average (UPGMA) and Jaccard's similarity coefficient. The UPGMA clustering showed a regrouping to the level species with high level of the structuration of the diversity at A. geniculata. We confirm as reported by other authors, the proximity of N genome to U genome and C genome to M genome and also the difference between the genomes M and N. Thus, the phylogeny between the species and the different genomes were retracted.