Polyploidy is an important feature for plant evolution. It is estimated that over 70% of flowering plants including important crops (e.g., canola, coffee, cotton, oats, sugarcane, and wheat) are polyploid. Little is known, however, about the expression of progenitors genes in polyploid genomes and molecular mechanisms associated with the evolutionary success of plant polyploids.

Origin of polyploidy: Two models for the origin of allopolyploids have been proposed. The "one-step" model suggests that an allotetraploid is formed by fusion of unreduced male and female gametes from two diploid species or by direct hybridization between two autotetraploid species, because almost every plant species produces a variable but small amount of unreduced gametes and many plant species are autotetraploids. The "two-step" model proposes that an allotetraploid is formed through hybridization between two diploid species followed by chromosome doubling of the F 1 hybrid. The "two-step" process, usually using mitotic inhibitors such as colchicine, has been used to produce artificial allotetraploids such as in Brassica and wheat.

Autopolyploidy: Duplication of a single genome. Examples include potato, alfalfa, and watermelon.

Allopolyploidy: Combination of two or more evolutionarily-divergent genomes. Examples include canola ( Brassica napus ), cotton, and wheat.

Paleopolyploidy: Ancient genome duplication that is diploidized. Examples include maize, cabbage, and Arabidopsis.

We are interested in understanding the genetic and epigenetic mechanisms of gene regulation in Arabidopsis allopolyploids. We hypothesize that plants use DNA sequence-independent or epigenetic mechanisms to regulate the expression of orthologous and paralogous genes following polyploidization. Using genetic, genomic, biochemical, and computational approaches, we are investigating how many genes, and by which mechanisms these genes are regulated during polyploid formation and evolution.

Related Research Projects

"Molecular Mechanisms of Genome Duplication" is funded by the National Institute of Health. "Functional Genomics of Plant Polyploids" is funded by the National Science Foundation. And, "Genetic and Functional Genomic Analysis of Early Events in Cotton Fiber Development" is funded by National Science Foundation.

Publications