Tandem 2: Evolution of sugar beet and its associated pathogens: implications for plant breeding and disease control

Background - Antagonistic interactions between plants and pathogens can result in a coevolutionary arms race between the two partners. Plants have evolved strategies to recognize and block invading pathogens while pathogens constantly evolve to escape recognition and manipulate host defenses. The domestication of plant species has been shaped by selective breeding and strong directional selection. Such artificial selection also impacts coevolutionary dynamics between crop plants and their pathogens. The evolution of plant pathogens is further shaped by the use of fungicides in agriculture. Their frequent application selects for resistant pathogen varieties. Sugar beet (Beta vulgaris) and its fungal pathogen Cercospora beticola provide an informative model system to study the impact of domestication, intensive crop cultivation and fungicide applications on the evolution of plant pathogens. This pathogen is increasingly important in beet production worldwide and fungicide resistance is a growing concern. B. vulgaris was domesticated in Germany approximately 200 years ago and is cultivated world-wide for sugar production. Leaf spot disease, as caused by C. beticola, is also a common pathogen of the wild progenitor of sugar beet, B. vulgaris ssp. maritima. The impact of host domestication on plant resistance and pathogen virulence can be studied in a comparative framework of wild and agricultural host-pathogen systems. Furthermore, the evolution of fungicide resistance can be studied by comparative analyses of pathogen populations on treated and untreated host plants.

Overall objectives

  • Assess the impact of selective breeding from the past 200 years on evolutionary processes by comparing genetic and functional data from cultivated and wild plant species.
  • Infer patterns of evolution in pathogen populations of C. beticola on wild and cultivated beet species using comparative population genomics.
  • Assess the ability of the fungal pathogen to adapt to fungicides and plant resistance mechanisms
  • Evaluate to what extent the availability of untreated plants determines the competition between susceptible and resistant pathogen strains.

Doctoral project 2.1: Genetic analysis of leaf spot resistance

Specific aims

  • Assess the impact of selective breeding in past 200 years in sugar beet
  • Dissect the genetics of C. beticola resistance in wild and cultivated beet species (QTL-, association mapping)
  • Fine-map a major QTL for C. beticola resistance
  • Clone and functionally analyse candidate genes from the QTL
  • Assess genetic diversity of resistance genes between beet and related wild species
  • Compare the diversity of resistance genes between beet and related wild species.

People working on this project

  • Prof. Dr. Christian Jung
  • MSc Amar Dhiman
  • Monika Bruisch

PI's Homepage: https://www.plantbreeding.uni-kiel.de/de

Doctoral project 2.2: Genetic analysis of leaf spot resistance

Specific aims

  • Assess the extent of host specialization and variation in levels of virulence of C. beticola using experimental assays involving B. vulgaris lines of PI Jung and B. vulgaris ssp. maritima as hosts.
  • Analyse the process of host specialization of C. beticola following host domestication by detailed analyses of genomic data and by the correlation of phenotype and genotype data.
  • Characterize the recent demography and population genetic structure of C. beticola populations on wild and cultivated plants

People working on this project

  • Eva H. Stukenbrock
  • Demetris Taliadores
  • Lizel Potgieter

PI's Homepage: http://web.evolbio.mpg.de/envgen/