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Abstract Detail

A Colloquium Honoring Leslie D. Gottlieb

Wendel, Jonathan [1].

From allozymes to sequenced genomes: Les Gottlieb and our understanding of polyploidy in plants.

It recently has become evident that all seed plants have experienced multiple rounds of whole genome doubling in their evolutionary histories. Les Gottlieb's interest in the number of genes that encode plant isozymes, their relative expression conservation among diploids, and utility for exploring polyploid evolution set the stage for many of the recent and extraordinary insights into polyploid genomes enabled by genome sequencing and the utilization of advanced high-throughput technologies. Gossypium includes classic allopolyploids arising from a biological reunion 1-2 MYA of divergent diploids from different hemispheres. This serendipitous merger generated a spectrum of genomic responses, including gene silencing, intergenomic gene conversion, and genome-wide disruption and modification of ancestral expression patterns. We are studying transcriptional, genomic and proteomic changes in synthetic and natural Gossypium allopolyploids using several technologies. Allopolyploid formation induces massive alteration in gene expression and complex transcriptomic responses, including genomic expression level dominance and homoeolog bias, transgressive expression patterns, and novel cytonuclear interactions. Using protocols that distinguish transcript levels for each homoeolog of each duplicated gene, we show that allopolyploidization entails significant homoeolog expression modulation that is temporally partitioned into alterations arising immediately as a consequence of genomic merger and secondarily as a result of longer-term changes in duplicate gene expression, the latter reflecting evolutionary forces such as duplicate gene neofunctionalization and subfunctionalization. We are exploring gene expression during cotton fiber development and evolution, taking advantage of a well-established phylogenetic framework and the unique opportunity offered bythe existence of multiple, parallel domestications of different wild progenitors by aboriginal peoples in both Africa-Asia and Mesoamerica. The fiber transcriptome is extraordinarily complex and has been massively altered by domestication. Homoeolog expression varies even at the level of development and maturation of a single cell, and domestication has increased expression bias in fibers towards the D-genome. Ongoing experiments are designed to evaluate the functional consequences of gene duplication in cotton and the possibility of novel gene recruitment following genome doubling. This work provides insights into the genetic architecture underlying the evolution of morphology, an additional central focus of Les Gottlieb's work, as well as additional evolutionary dimensions of polyploidy.

Broader Impacts:

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Related Links:
Wendel lab page

1 - Iowa State University, Department of Ecology, Evolution, And Organismal Biology, 251 BESSEY HALL, AMES, IA, 50011-1020, USA

Gene expression

Presentation Type: Symposium or Colloquium Presentation
Session: C1
Location: Grand Ballroom A/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 11:30 AM
Number: C1012
Abstract ID:120
Candidate for Awards:None

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