Genomic Studies in Monocots
The project is aimed at documenting and understanding the evolutionary significance of the extensive genomic diversity encountered in monocots using a range of traditional and molecular cytogenetic methods to probe the genome.
The Crown Imperial (Fritillaria imperialis) has one of the largest genomes known for angiosperms (c. 94 pg of DNA divided into 24 chromosomes) - the bulk of which is composed of highly repetitive DNA.
Monocot genomic diversity includes striking variation in nuclear DNA at many levels ranging from base sequences within and between genes, the number of chromosomes per genome, the number of genomes (ploidy) and the amount of DNA per genome (genome size). As part of a long-term, ongoing project based at the Jodrell Laboratory the evolutionary significance of this genome diversity is being studied in selected monocot groups, making use of the increasingly robust phylogenetic information being generated in the Jodrell and the extensive living collections at Kew. Research techniques include: (i) Classical cytogenetics to count and characterize chromosome morphology, including C-banding; (ii) Various types of fluorescence in situ hybridization including chromosome painting to determine how particular DNA sequences are organized along chromosomes and how whole genomes are organized in hybrid and polyploid species; (iii) Feulgen microdensitometry and flow cytometry to estimate the genome size and (iv) Molecular sequencing tools for characterizing the evolution of some of the many repetitive DNA sequences that make up the bulk of many monocot genomes. Current foci of study are Asparagales (including Orchidaceae) and Liliales, two of the orders with the greatest range of genome size.
A three-year funded NERC grant (2010 - 2013) entitled 'Evolutionary dynamics of genome obesity’ is focusing specifically on the genus Fritillaria (Liliaceae) which contains the species with the largest diploid genome so far reported in plants (Fritillaria shikokiana), its genome is over 30x bigger than our own! The research combines high-throughput DNA sequencing, bioinformatics and chromosome painting strategies on selected Fritillaria species to investigate the dynamics and evolution of highly repeated DNA sequences which comprise the bulk of their obese genomes.
Outputs of the project are being published in peer-reviewed journals and are frequently presented at international scientific meetings. In addition, novel genome size data are contributed to the Plant DNA C-values database project (under Large Scale Syntheses). Items of interest to the general public are also disseminated through the Kew Press Office, including the discovery of possibly the largest genome for any eukaryote in Paris japonica (Melanthiaceae, Liliales) based on material analyzed from the RBG Kew living collection.
Project partners and collaborators
Institute of Plant Molecular Biology, Ceske Budejovice
Department of Functional Genomics and Proteomics, University of Masaryk, Brno
Charles University, Prague
Department of Plant Biology, University of Georgia
University of the Free State, Bloemfontein, South Africa