Qualifications & Appointments
BSc (Hons), Univ. Bristol, 1985
PhD, Univ. Bristol, 1990.
To understand the evolutionary significance of the immense diversity of plant genomes (i.e. size, chromosome number, organization and composition).
Research into increasing knowledge of plant genome organisation and evolution focuses on three areas:
(1) Physical organization of genomes - patterns, constraints and evolution: the physical organization of DNA within chromosomes and between whole chromosomes and genomes is studied using fluorescence in situ hybridisation (FISH) including chromosome painting strategies (genomic in situ hybridisation, GISH), which enable whole genomes to be visualised in hybrid and polyploid taxa; understanding how specific DNA sequences are organised within chromosomes highlights possible evolutionary constraints on genome organisation; visualizing the organisation of different genomes in hybrids and polyploids provides insights into how genomes evolve following polyploid formation, a process estimated to have occurred at least once in all angiosperms.
(2) Plant genome size - ; diversity and evolution: estimating, collating (including the Plant DNA C-values database www.kew.org/genomesize/homepage.html) and analysing data has provided insights into our understanding of the evolutionary significance of the huge range (nearly 2,400-fold) of C-values encountered in land plants (embryophytes). Superimposing C-value data onto increasingly robust phylogenies of land plant groups allows predications to be made as to the size of ancestral genomes and to document where increases and decreases in genome size may have taken place during evolution. Analysing genome size evolution in polyploids reveals that DNA loss or genomic downsizing is a frequent response to the increased genomic DNA load of polyploidy nucleus. Tracking the exact timing and magnitude of DNA loss is currently being investigated in a range of polyploids.
(3) Composition, organisation and dynamics of genome: Understanding the mechanisms and evolutionary forces which maintain or change genome size is currently a hot topic of debate. Ongoing work focusing on Liliaceae and, in particular, species in the genus Fritillaria (which includes the largest diploid genomes so far reported in plants), aims to investigate this further by analysing the composition, organisation and evolutionary dynamics of various classes of repetitive DNAs (e.g. retrotransposons and satellites) which make up the bulk of their genome. These studies combine next generation sequencing strategies such as 454 and Illumina sequencing, together with molecular cytogenetic techniques of FISH and GISH.
- Genomic studies on UK flora: cytotype distribution and incidence of polyploidy
- Genomic Studies in Angiosperms
- Genomic Studies in Monocots
- Hybridization and Polyploidy – Major Factors in Angiosperm Evolution: a Case Study of Nicotiana (Solanceae)
- Phylogeny and karyology of Psidium and Campomanesia
- Plant DNA C-Values Database
- Systematics and Conservation Genetics of Asparagales
- Systematics and Genetics of Liliales
Selected Recent Publications
Kelly LJ, Leitch IJ. 2011. Exploring giant plant genomes with next-generation sequencing technology. Chromosome Research: (in press).
Pellicer J, Fay MF, Leitch IJ. 2010. The largest eukaryotic genome of them all? Botanical Journal of the Linnean Society 164: 10-15.
Bennett MD, Leitch IJ. 2011. Nuclear DNA amounts in angiosperms - targets, trends and tomorrow. Annals of Botany 107: 467-590.
Leitch IJ, Beaulieu JM, Chase MW, Leitch AR, Fay MF. 2010. Genome size dynamics and evolution in monocots. Journal of Botany 2010: Article ID 862516, 18 pages, doi:10.1155/2010/862516.
Kejnovsky E, Leitch IJ, Leitch AR. 2009. Contrasting evolutionary dynamics between angiosperm and mammalian genomes. Trends in Ecology & Evolution 24: 572-582.
Ambrožová K, Macas J, Neumann P, Leitch IJ, Lysak MA. 2009. Molecular and cytogenetic analysis of the giant genomes of Fritillaria lilies. Chromosome Research 17: 558-559.
Leitch IJ, Kahandawala I, Suda J, Hanson L, Ingrouille MJ, Chase MW, Fay MF. 2009. Genome size diversity in orchids - consequences and evolution. Annals of Botany 104: 469-481.
- Lysák, M.A., Koch, M.A., Beaulieu, J.M., Meister, A. & Leitch, I.J. (2009). The dynamic ups and downs of genome size evolution in Brassicaceae. Molecular Biology and Evolution 26: 85-98.
Selected Earlier Publications
Leitch, A.R. & Leitch, I.J. (2008). Genomic plasticity and the diversity of polyploid plants. Science 320: 481-483.
Beaulieu, J.M., Leitch, I.J., Patel, S., Pendharkar, A. & Knight, C.A. (2008). Genome size is a strong predictor of cell size and stomatal density in angiosperms. New Phytologist 179: 975–986.
Leitch, I.J., Hanson, L., Lim, K.Y., Kovarik, A., Chase, M.W., Clarkson, J.J. & Leitch, A.R. (2008). The ups and downs of genome size evolution in polyploid species of Nicotiana (Solanaceae). Annals of Botany 101: 805-814.
- Leitch, I.J., Beaulieu, J.M., Cheung, K., Hanson, L., Lysak, M. & Fay, M.F. (2007). Punctuated genome size evolution in Liliaceae. Journal of Evolutionary Biology 20: 2296-2308.
- Leitch, I.J., Soltis, D.E., Soltis, P.S. & Bennett, M.D. (2005). Evolution of DNA amounts across land plants (Embryophyta). Annals of Botany 95: 207-217.
- Leitch, I.J. (2007). Genome sizes through the ages. Heredity 99: 121-122.
- Leitch, I.J. & Bennett, M.D. (2004). Genome downsizing in polyploid plants. Biological Journal of the Linnean Society 82: 651-663.
- Soltis, D.E., Soltis, P.S., Bennett, M.D. & Leitch, I.J. (2003). Evolution of genome size in the angiosperms. American Journal of Botany 90: 1596-1603.