Description of Research Interests:

Development of microsatellite markers for mapping and cultivar identification of Rosaceous species.

Development of gene-specific markers for comparative mapping between genera in Rosaceae.

Development of molecular maps of Rosaceous fruit crops and ornamentals.

Genome evolution in Rosaceae.

The genetics of self-(in)compatibility in Rosaceous species.

Collaborative Links:

Institut de Recerca i Tecnologia Agroalimentáries (IRTA), Cabrils, Spain.

The University of Reading, UK.

The University of Florida, USA.

The University of New Hampshire, USA.

The University of Udine, Italy.

Clemson Univerity, USA.

INRA Bordeaux, France.

Virginia Bioinformatics Institute, USA.

The Norwegian Institute for Agricultural and Environmental Research, Norway.

North Carolina State University, USA

Victorian AgriBiosciences Centre, Australia

Current Research Projects:

2004-2008 Defra funded project: HH3724SSF: ‘Comparative genomics of rosaceous fruit crops and HNS for sustainable production’.

2007-2010 BBSRC funded project ‘A genetic system to study resistance to the soil-borne pathogen Verticillium dahliae in strawberry’.

Nature of current employment:

Post graduate research scientist

Principal researcher on the Defra-funded project:  HH3724SSF: Comparative genomics of rosaceous fruit crops and HNS for sustainable production.

Reviewer for Theoretical and Applied Genetics; Planta; Journal of the American Society for Horticultural Science; the International Society for Horticultural Science.

Reviewer for grant proposals for the National Science Foundation of America (NSF) and the Binational Agricultural Research & Development Fund (BARD).

Member of Working Group 1 for EU COST Action 863 ‘Euroberry’.

Supervisor for visiting workers and students from the UK and abroad in the molecular genetics laboratory at EMR.

Qualifications:

2000    BSc (Hons) First Class in Biological Sciences. Manchester Metropolitan University (MMU), UK.

2001    Post Graduate Certificate of Education. MMU, UK.

2005    PhD: ‘A genetic investigation of diploid Fragaria’. University of Reading, UK and East Malling Research (EMR).

Career history:

Band 5 Research Scientist (permanent position), studying the molecular genetics of Rosaceous species, East Malling Reaserch, UK (2005-present).

I studied for a PhD at the University of Reading, undertaking the majority of my research at East Malling Research in Kent.  My thesis was entitled ‘A genetic investigation of diploid Fragaria’ and was supervised at the University of Reading by Professor Nick Battey and at East Malling by Dr David Simpson.  In this work I studied many aspects of wild strawberry genetics, including phylogenetics, interspecific cross-compatibility and morphological variation within and between species, but the main focus of the research was the development of molecular tools for linkage map development in Fragaria.  To this end, I developed a suite of 48 microsatellite (SSR) markers from three wild strawberry species, F. nubicola, F. vesca and F. viridis and performed many pair-wise interspecific diploid Fragaria crosses, raising a number of segregating mapping populations.  One of the F₂ progenies raised, (derived from the initial F₁ cross F. vesca 815 × F. nubicola 601) proved particularly polymorphic at the molecular level and I chose this as the population from which to develop an SSR map of diploid Fragaria.  Using this population, I mapped a total of 68 SSR markers, six STS markers for genes of known function.  In addition, the population segregated for three morphological traits non-runnering (r), perpetual flowering (s) and pale green leaf (pg) and a number of QTL, all of which were mapped to loci on the molecular linkage map developed.  I successfully defended my research project in March 2005 and my thesis work resulted in a number of refereed publications as well as conference proceedings.  My thesis and selected papers can be downloaded as PDFs from the reference section of this site.

I was appointed to a post-doctoral research position at East Malling research in 2005 and from that time until the present date, I have continued with research on Rosaceous genetics and genomics, building on the research started during my PhD.  This has included the extension of the diploid Fragaria mapping work, with the 815 × 601 population being adopted as the reference mapping population for the genus (now denoted FV×FN).  The map has been extended through international collaborative efforts between EMR and partners in both Europe and the USA to include 312 molecular loci: 230 SSRs, 26 gene-specific markers 40 RFLPs, 15 ESTs and one SCAR.  In collaboration with partners in Spain at IRTA Cabrils (Pere Arùs, Amparo Monfort and Santiago Villanova), a selective mapping strategy has been adopted using the FV×FN population, and now markers can be assigned to one of 40 bins on the Fragaria likage map using just 6 seedlings from the full population.

In addition to work in Fragaria, the work has extended to the development of molecular maps of Rubus, Prunus and Physocarpus, in addition to the development of markers from Rosaceous gene sequences that are transferable and polymorphic across genera, and thus useful for comparative mapping purposes.  One major current activity is the determination of synteny between Fragaria, Malus and Prunus using gene-specific markers, isoenzymes and RFLPs and in collaboration with IRTA cabrils, over 50 orthologous loci have been mapped in the Fragaria and Prunus reference maps.

Selected recent publications:

Refereed publications

Hadonou AM, Sargent DJ, Wilson F, James CM, Simpson DW (2004).  Development of microsatellite markers in Fragaria, their use in genetic diversity analysis and their potential for genetic linkage mapping. Genome 47: 1-14.

Nier S, Simpson DW, Tobutt KR, Sargent, DJ (2006).  Construction of a genetic linkage map of an interspecific diploid Fragaria BC1 mapping population (F. vesca 815 x [F. vesca 815 x F. viridis 903]) and its comparison to the Fragaria reference map (FVxFN).   Journal of Horticultural Science and Biotechnology 81: 645-650.

Ortega E, Boskovic RI, Sargent DJ, Tobutt KR (2006).  Analysis of S-RNase alleles of almond (Prunus dulcis): characterization of new sequences, resolution of synonyms and evidence of intragenic recombination Molecular Genetics and Genomics 276: 413-426.

Sargent DJ, Marchese A, Simpson DW, Howad W, Fernández-Fernández F, Monfort A, Arús P, Evans KM, Tobutt KR.  Development of ‘universal’ gene-specific markers from Malus pumila cDNA sequences, their mapping and use in synteny studies within Rosaceae.  Tree Genetics and Genomes (in press)

Sargent DJ, Cipriani G, Vilanova S, Gil-Ariza D, Arús P, Simpson DW, Tobutt KR, Monfort A (2008).  The development of a bin mapping population and the selective mapping of 103 markers in the diploid Fragaria reference map.  Genome 51: 120–127 doi:10.1139/G07-107

Sargent DJ, Fernández-Fernández F, Rys A, Knight VH, Simpson DW, Tobutt KR (2007).  Mapping of A₁ conferring resistance to the aphid Amphorophora idaei and dw (dwarfing habit) in red raspberry (Rubus idaeus L.) using AFLP and microsatellite markers.  BMC Plant Biology 7:15.

Sargent DJ, Rys A, Nier S, Simpson DW, Tobutt KR, (2007).  The development and mapping of functional markers in Fragaria and their transferability and potential for mapping in other genera.  Theoretical and Applied Genetics 114: 373-384.

Sargent DJ, Clarke J, Simpson DW, Tobutt KR,  Arús P, Monfort A, Vilanova S, Denoyes‑Rothan B, Rousseau M, Folta KM, Bassil NV, Battey NH (2006).  An enhanced microsatellite map of diploid Fragaria. Theoretical and Applied Genetics 112: 1349-1359

Sargent DJ, Davis TM, Tobutt KR, Wilkinson MJ, Battey NH, Simpson DW (2004).  A genetic linkage map of microsatellite, gene specific and morphological markers in diploid Fragaria.  Theoretical and Applied Genetics 109: 1385-1391.

Sargent DJ, Geibel M, Hawkins JA, Wilkinson MJ, Battey NH Simpson DW (2004). Morphological traits in diploid Fragaria for the study of the genetic basis of phenotypic differences between species. Annals of Botany 94: 787-796.

Sargent DJ, Hadonou AM, Simpson DW (2003). Development and characterization of polymorphic microsatellite markers from Fragaria viridis, a wild diploid strawberry. Molecular Ecology Notes 3: 550-552.

Šurbanovski N, Tobutt KR, Konstantinović M, Maksimović V, Sargent DJ, Stevanović V, Ortega E, Bošković RI (2007).  Self-incompatibility of Prunus tenella and evidence that reproductively isolated species of Prunus have different SFB alleles coupled with an identical S-RNase allele.  The Plant Journal 50: 723-734.

Sutherland BG, Tobutt KR, Marchese A, Paternoster G, Simpson DW, Sargent DJ (2008).  A genetic linkage map of Physocarpus, a member of the Spiraeoideae (Rosaceae), based on RAPD, AFLP, RGA, SSR and gene specific markers.  Plant Breeding (in press).

Vaughan SP, Russell K, Sargent DJ, Tobutt, KR (2006).  Isolation of S-locus F-box alleles in Prunus avium and their application in a novel method to determine self-incompatibility genotype.  Theoretical and Applied Genetics 112: 856-866.

Conference proceedings

Hadonou AM, Sargent DJ, Simpson DW (2004).  Characterisation of Fragaria simple sequence repeats (SSR) markers. Acta Horticulturae 649: 99-102

Sargent DJ, Battey NH, Wilkinson MJ, Simpson DW (2006). The detection of QTL associated with vegetative and reproductive traits in diploid Fragaria: A preliminary study. Proceedings of the 5^th ISHS Strawberry Symposium, Queensland, Australia, September 6-10, 2004.  Acta Horticulturae 708: 471-474.

Sargent DJ, Hadonou AM, Wilkinson MJ, Battey NH, Hawkins JA, Simpson DW (2004). Cross‑species amplification and phylogenetic reconstruction using Fragaria microsatellite primers. Acta Horticulturae 649: 87-92.

PhD thesis

Sargent DJ (2005).  A genetic investigation of diploid Fragaria.  PhD thesis, The University of Reading pp223.