Evolution of flowering plants

Amborella trichopoda, basal to all other flowering plants
(Wikimedia Commons)

Amborella is a sprawling shrub endemic to New Caledonia. This monotypic genus is basal to the angiosperms and sister to all other flowering plants. Now its mitochondrial and nuclear genomes have been sequenced and this is the subject of three papers in the current issue of Science (summarized here).

Amongst other things it addresses Darwin's "abominable mystery" - the question of why flowers suddenly proliferated on earth millions of years ago (discussed in this press release). It confirms, as had previously been suspected, that the evolution of flowering plants was preceded by a genome duplication.

Whole genome duplication has also played a significant role in the evolution of vertebrates (reviewed here). Tandem duplication of genes or groups of genes is common in the mammalian lineage and the basis for the evolution of placental hormones and fetal hemoglobins (my review here).

Footnote: In botany, placentation refers to the manner in which the ovules are attached within the ovary. It is an important taxonomic feature.