Jennifer Tate

Lecturer in Plant Systematics and Evolution
Institute of Molecular BioSciences
Allan Wilson Centre for Molecular Ecology and Evolution
Massey University
Email: j.tate@massey.ac.nz

Research Interests

Much of my research has focused on the evolution of plant polyploids, from identifying the progenitors of polyploid species using phylogenetic methods, to examining the fate of genes duplicated by polyploidy using molecular genetic techniques. Polyploidy can have significant consequences on the entire organism, from genomic incompatibilities to changes in ecological tolerances. As a result, studies of polyploidy naturally allow for an integrative approach to research. The main goals of my research are to identify progenitor species of natural polyploids, so that the genetic, genomic, and phenotypic consequences of polyploidy in natural systems can be understood.

Genome evolution in Tragopogon (Asteraceae) allopolyploids

Genome evolution in the New World allopolyploid Tragopogon species, T. miscellus and T. mirus, is being examined using a variety of molecular approaches (cDNA-AFLP, RT-PCR, CAPS, SNPs). This group has been the focus of much interest over the last several decades, because it provides a unique opportunity to study the consequences of recent and recurrent polyploidisation in a natural setting. Following the introduction of three diploid Tragopogon species (T. dubius, T. pratensis, and T. porrifolius) to the Palouse region in the northwestern United States from Eurasia, two allopolyploid species (T. mirus and T. miscellus) formed within the last 100 years. Tragopogon miscellus is of particular interest because it has formed reciprocally from T. dubius and T. pratensis. The reciprocally formed populations of T. miscellus differ in their inflorescence and floral morphologies: when T. dubius is the maternal progenitor, T. miscellus has long ligules and when T. pratensis is the maternal parent, the ligules are short.

For this project, which is in collaboration with the Soltis lab at the University of Florida, we are investigating the genomic and transcriptomic changes that occur in the early stages of polyploid evolution. To accomplish this goal, we are creating synthetic hybrids and polyploids by crossing the appropriate diploid progenitors (T. dubius, T. pratensis, and T. porrifolius) that gave rise to T. miscellus and T. mirus. Recent data from cDNA-AFLPs and genomic and cDNA cleaved amplified polymorphic sequence (CAPS) analysis revealed that T. miscellus individuals from two reciprocally formed populations have experienced frequent and stochastic loss of one parental gene copy for several loci (Tate et al. 2006). As these polyploids are fewer than 40 generations old (they are biennials), these genomic changes have occurred rapidly. Synthetic F1 hybrids are completely additive of their parental genomes, suggesting that polyploidisation may act as a ‘genomic shock’ (Tate et al. 2006).

These studies will provide an important framework for an investigation of Tragopogon in New Zealand, where all three diploid progenitors are known to occur. Herbarium specimen localities indicate that pairs of the diploids are likely sympatric, but whether they are hybridising and forming polyploids is not known. Insights from the Tragopogon tetraploids will allow a better understanding of how other natural polyploid species establish and succeed in worldwide floras.

Distribution of Tragopogon in New Zealand
(from Landcare Research website)

Recent Tragopogon Publications
	Tate, J. A., Z. Ni, A.-C. Scheen, J. Koh, C. Gilbert, Z. J. Chen, P. S. Soltis, and D. E. Soltis. 2006. Evolution and expression of homeologous loci in Tragopogon miscellus (Asteraceae), a recent and reciprocally formed allopolyploid. Genetics 173: 1599-1611.
	Soltis, D. E., P. S. Soltis, J. C. Pires, A. Kovarik, J. A. Tate, and E. Mavrodiev. 2004. Recent and recurrent polyploidy in Tragopogon (Asteraceae): Genetic, genomic, and cytogenetic comparisons. Biological Journal of the Linnean Society 82: 485-501.