Project 6

Convergent evolution of metabolic pathways: The biosynthesis of benzoxazinoids in dicotyledonous plants

Supervisors: Sarah O'Connor, MPI for Chemical Ecology, Tobias Köllner, MPI for Chemical Ecology

Background: Benzoxazinoids are indole-derived plant defense compounds that are mainly produced in the grasses, but also in a few species of the Ranunculales and Lamiales (1). While the biosynthesis of these compounds has been extensively investigated in maize, wheat, and other cereals (2-4), little is known about their formation in dicotyledonous plants. However, sequence comparisons, enzyme inhibitor studies, and labeling experiments suggest that the benzoxazinoid pathways in the Poales, Ranunculales, and Lamiales evolved independently from each other by convergent evolution (5, 6).  

Project Description: The aim of this project is to elucidate the formation of benzoxazinoids in Aphelandra squarrosa and Consolida orientalis, two species that belong to the Lamiales and Ranunculales, respectively. The PhD candidate will combine transcriptomics and metabolomics approaches to identify candidate genes potentially involved in the different pathways. Genes will be expressed heterologously in Nicotiana benthamiana, yeast, and/or Escherichia coli and recombinant enzymes will be characterized in vivo and in vitro. The obtained results will enable us to gain insights into the genetic and molecular mechanisms underlying the convergent evolution of metabolic pathways in plants. Moreover, knowledge about the regulation of benzoxazinoid formation in A. squarrosa and C. orientalis will help to understand the biological roles of these compounds in dicotyledonous plants.

Candidate profile: We are searching for a highly motivated student with a Master´s degree or equivalent who has a strong background in biochemistry and/or molecular biology. Excellent communication skills in written and spoken English are required. Experiences in protein biochemistry, plant transformation, and LC-MS/MS techniques would be desirable, but not absolutely necessary. We offer an excellent research environment with enthusiastic scientists from different nationalities in the recently established Department of Natural Product Biosynthesis (director: Prof. Sarah E. O’Connor) at the Max Planck Institute for Chemical Ecology in Jena, Germany.

References:

  •  H.M. Niemeyer (2009) Hydroxamic acids derived from 2-hydroxy-2H-1,4-benzoxazin-3(4H)-one: Key defense chemicals of cereals. J. Agric. Food Chem. 57, 1677–169
  • M. Frey et al. (2009) Benzoxazinoid biosynthesis, a model for evolution of secondary metabolic pathways in plants. Phytochemistry 70, 1645–1651
  • V. Handrick et al. (2016) Biosynthesis of 8-O-methylated benzoxazinoid defense compounds in maize. The Plant Cell 28, 1682–1700
  • B. Li et al. (2018) Convergent evolution of a metabolic switch between aphid and caterpillar resistance in cereals. Science Advances 4, eaat6797
  • K. Schullehner et al. (2008) Benzoxazinoid biosynthesis in dicot plants. Phytochemistry 69, 2668–2677
  • R. Dick et al. (2012) Comparative analysis of benzoxazinoid biosynthesis in monocots and dicots: Independent recruitment of stabilization and activation functions. The Plant Cell 24, 915–928                         

Project 6 pdf