Project suggestions
Supervisor(s): Allan Rasmusson, Bradley Dotson, Dept. Biology, LU
Many fungal species of the genus Trichoderma live in symbiosis with plant roots. The fungus produces substances that stimulate plant growth and immune system but also directly attacking other microorganisms, including pathogens. Therefore, some strains of Trichoderma have been used as biocontrol and biostimulants in agriculture, decreasing the need for agrochemical use. The effect of Trichoderma on plants is strongly dependent on the plant genome, which is involved in a mainly unknown intricate interaction with the fungus, likely involving exchange of several signalling biomolecules. Plant genes that are essential for biostimulation and biocontrol by fungi can be used in breeding, to make plants that can better benefit from biocontrol and biostimulation. However, we presently do not know what genes these are.
One possible class of genes that are essential for positive symbiosis with fungi are plant genes encoding proteins that are needed for the plants to avoid being damaged by the Trichoderma. This fungus attacks other microorganisms by secreting enzymes and peptide antibiotics, including so called peptaibols, where alamethicin is the standard model example. This peptide also lyses plant cells, but cellulase secreted from the Trichoderma induces resistance to the alamethicin by modifying the composition of the plant plasma membrane. This process we have named CIRA, and it is likely important for plant symbiosis with Trichoderma, though direct evidence are lacking. We have isolated CIRA-deficient mutants for a range of Arabidopsis genes, indicating that a so far unknown response chain is active. The different mutants belong to the categories Gene expression, Cell wall modifying, Signalling, Membrane lipid modifying and “Unknown”.
We can design differently long projects (30-60 credits) at multiple levels:
- Whole plant level comparison of genetics of inbred sugar beet breeding lines as expressed in their biostimulation phenotypes. Includes work with molecular markers, genotyping and phenotyping on soil.
- Analysis of particular known Arabidopsis mutants, their (lack of) biostimulation by Trichoderma, and the potential involvement of calcium signalling. This will involve sterile plant growth, fluorescent microscopy and measurements using intracellular fluorescent reporters.
- Identification and analysis of novel CIRA genes by mutant screening. Arabidopsis CIRA mutants are identified by a fluorescent phenotypic change and verified by designing PCR assays and analysing a second mutant allele for the same gene. The genes found are analysed in a first line by bioinformatic database mining (e.g. gene expression patterns, protein localisation, post-translational modification, etc). In a longer project additional analyses can be done. Acquired data will be used in order to assemble a preliminary signalling path.
For the sugar beet project, background knowledge on plant physiology, genetics and/or agriculture is suitable. For the Arabidopsis projects, background knowledge on plant physiology, molecular cell biology and molecular genetics is suitable. However, a project can usually be designed in accordance with the background of a candidate.
For more information and discussions please contact allan.rasmusson@biol.lu.se or bradley.dotson@biol.lu.se.