Expression evolution following WGD and fractionation in maize
Klaas
Differentiation of the maize subgenomes by genome dominance and
both ancient and ongoing gene loss
James C. Schnablea, Nathan M. Springer and Michael Freeling
Abstract
Ancient tetraploidies are found throughout the eukaryotes. After
duplication, one copy of each duplicate gene pair tends to be lost
(fractionate). For all studied tetraploidies, the loss of duplicated
genes, known as homeologs, homoeologs, ohnologs, or syntenic
paralogs, is uneven between duplicate regions. In maize, a species
that experienced a tetraploidy 5–12 million years ago, we show that
in addition to uneven ancient gene loss, the two complete genomes
contained within maize are differentiated by ongoing fractionation
among diverse inbreds as well as by a pattern of overexpression of
genes from the genome that has experienced less gene loss. These
expression differences are consistent over a range of experiments
quantifying RNA abundance in different tissues. We propose that the
universal bias in gene loss between the genomes of this ancient
tetraploid, and perhaps all tetraploids, is the result of selection
against loss of the gene responsible for the majority of total
expression for a duplicate gene pair. Although the tetraploidy of
maize is ancient, biased gene loss and expression continue today and
explain, at least in part, the remarkable genetic diversity found
among modern maize cultivars.
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Prof. Dr. Klaas Vandepoele
Tel. 32 (0)9 33 13822
VIB Department of Plant Systems Biology, Ghent University
Technologiepark 927, 9052 Gent, Belgium
E-mail: Klaas.Vandepoele@psb.vib-ugent.be
Website: http://bioinformatics.psb.ugent.be/cig/
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Conference & Workshop
Comparative & Regulatory Genomics in Plants
Website: http://bioinformatics.psb.ugent.be/crg_event/
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