Reference "Phylogeny of rice genomes with emphasis on origins of allotetraploid species"

Reference ID

1113

Title

Phylogeny of rice genomes with emphasis on origins of allotetraploid species

Source

Proceedings of the National Academy of Sciences of the United States of America, 1999, vol. 96, pp. 14400-14405

Authors (4)

Ge-S	Sang-T
Lu-B-R	Hong-D-Y

Abstract

The rice genus, Oryza, which comprises 23 species and 9 recognized genome types,
represents an enormous gene pool for genetic improvement of rice cultivars.
Clarification of phylogenetic relationships of rice genomes is critical for
effective utilization of the wild rice germ plasm. By generating and comparing
two nuclear gene (Adh1 and Adh2) trees and a chloroplast gene (matK) tree of all
rice species, phylogenetic relationships among the rice genomes were inferred.
Origins of the allotetraploid species, which constitute more than one- third of
rice species diversity, were reconstructed based on the Adh gene phylogenies.
Genome types of the maternal parents of allotetraploid species were determined
based on the matK gene tree. The phylogenetic reconstruction largely supports
the previous recognition of rice genomes. It further revealed that the EE genome
species is most closely related to the DD genome progenitor that gave rise to
the CCDD genome. Three species of the CCDD genome may have originated through a
single hybridization event, and their maternal parent had the CC genome. The
BBCC genome species had different origins, and their maternal parents had either
a BB or CC genome. An additional genome type, HHKK, was recognized for Oryza
schlechteri and Porteresia coarctata, suggesting that P. coarctata is an Oryza
species. The AA genome lineage, which contains cultivated rice, is a recently
diverged and rapidly radiated lineage within the rice genus.