Phylogenetic reconstruction of ancient photosynthetic lineages using chlorophyll and bacteriochlorophyll biosynthetic genes

摘要

Photosynthesis is an ancient process. Geochemical evidence of organisms that resemble cyanobacteria is approx 2.5 billion years old (Summons et al., 1999). It is generally assumed that more primitive photosynthetic bacteria have existed as far back as 3.5 billion yearsago (Schopf, 1993), so gaining knowledge about these organisms and their evolutionary history is an extremely difficult challenge.