Reference "Phylogenetic analysis of the acetyl-CoA carboxylase and 3-phosphoglycerate kinase loci in wheat and other grasses"

Reference ID

7652

Title

Phylogenetic analysis of the acetyl-CoA carboxylase and 3-phosphoglycerate kinase loci in wheat and other grasses

Source

Plant molecular biology, 2002, vol. 48, pp. 805-820

Authors (7)

Huang-S	Sirikhachornkit-A
Faris-J-D	Su-X
Gill-B-S	Haselkorn-R
Gornicki-P

Abstract

We have applied a two-gene system based on the sequences of nuclear genes
encoding multi-domain plastid acetyl-CoA carboxylase (ACCase) and plastid 3-
phosphoglycerate kinase (PGK) to study grass evolution. Our analysis revealed
that these genes are single-copy in most of the grass species studied, allowing
the establishment of orthologous relationships between them. These relationships
are consistent with the known facts of their evolution: the eukaryotic origin of
the plastid ACCase, created by duplication of a gene encoding the cytosolic multi-
domain ACCase gene early in grass evolution, and the prokaryotic (endosymbiont)
origin of the plastid PGK. The major phylogenetic relationships among grasses
deduced from the nucleotide sequence comparisons of ACCase and PGK genes are
consistent with each other and with the milestones of grass evolution revealed
by other methods. Nucleotide substitution rates were calculated based on
multiple pairwise sequence comparisons. On a relative basis, with the divergence
of the Pooideae and Panicoideae subfamilies set at 60 million years ago (MYA),
events leading to the Triticum/Aegilops complex occurred at the following
intervals: divergence of Lolium (Lolium rigidum) at 35 MYA, divergence of
Hordeum (Hordeum vulgare) at 11 MYA and divergence of Secale (Secale cereale) at
7 MYA. On the same scale, gene duplication leading to the multi-domain plastid
ACCase in grasses occurred at 129 MYA, divergence of grass and dicot plastid PGK
genes at 137 MYA, and divergence of grass and dicot cytosolic PGK genes at 155
MYA. The ACCase and PGK genes provide a well-understood two-locus system to
study grass phylogeny, evolution and systematics.