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Leitch, Ilia J.

Photo of Ilia Leitch
Job title: 

Plant Genetics Scientist

Joined Kew: 


Foreign languages: 


Qualifications and 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) 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.

Selected publications: 

Leitch, A. R., Leitch, I. J., Trimmer, M., Guignard, M. S., Woodward, G. (2014). Impact of genomic diversity in river ecosystems. Trends in Plant Science: Online early

Leitch, A. R., Leitch, I. J. (2012). Ecological and genetic factors linked to contrasting genome dynamics in seed plants. New Phytologist 194: 629-646. Available online

Kelly, L.J, Leitch IJ. 2011. Exploring giant plant genomes with next-generation sequencing technology. Chromosome Research 19: 939-953. Available online

Lomax, B. H., Hilton, J., Bateman, R. M., Upchurch, G. R., Lake, J. A., Leitch, I. J., Cromwell, A., Knight, C. A. (2014). Reconstructing relative genome size of vascular plants through geological time. New Phytologist 201: 636-644. Available online

Garcia, S., Leitch, I. J., Anadon-Rosell, A., Canela, M. Á., Gálvez, F., Garnatje, T., Gras, A., Hidalgo, O., Johnston, E., Mas de Xaxars, G., Pellicer, J., Siljak-Yakovlev, S., Vallès, J., Vitales, D., Bennett, M. D. (2014). Recent updates and developments to plant genome size databases. Nucleic Acids Research 42: D1159-D1166. Available online