Plant & Animal Genomes XVII Conference Plant & Animal Genomes XVII ConferenceJanuary 10-14, 2009
Town & Country Convention Center
San Diego, CA
Increasingly powerful technologies are being applied to polyploids in many plant groups, resulting in dramatic discoveries of novel genomic interactions. 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 responses, including disruption and subsequent reconciliation of ancestral gene expression patterns. Using several microarray platforms and other technologies, we are studying global transcriptional changes in synthetic and natural Gossypium allopolyploids and reconstructed F1 and polyploid hybrids, using differing tissues and genetic backgrounds. Allopolyploid formation induces massive alteration in gene expression and complex transcriptomic responses, including genome-wide genomic dominance and novel (transgressive) expression patterns. Using a novel microarray that simultaneously distinguishes transcript levels for each homoeolog, 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 long-term evolutionary transformations in duplicate gene expression. Expression in some tissues may be biased such that there is an overall unequal contribution of two genomes to the transcriptome. Homoeolog expression ratios change during fiber development, showing that duplicate gene expression modulation even characterizes the development of a single cell. We are exploring the functional consequences of gene duplication in cotton and the possibility of novel gene recruitment following genome doubling.