Aim 1. Utilizing existing plant mutants and allelic variation to elucidate general microbe accessibility mechanisms.
We have identified new genetic components underlying root interactions in Medicago and root and leaf interactions in barley. We assessed mutants impaired in specific symbiotic interactions for their impact on the interaction with an aggressive broad range pathogen. We cloned the gene underlying the M. truncatula api mutation. Our work suggests that specific changes in the plant cell wall at root tips have a dramatic effect on plant microbe interactions without major impacts on overall development. This change in cell wall properties contributes to the quantitative resistance phenotype. These and other findings are published in Gavrin et al., 2020, Current Biology.
We also have utilized natural variation in M. truncatula to identify a GRAS transcription factor as being involved in pathogen and symbiont interaction (Rey et al., 2017, J. Exp. Bot.).
We have shown that barley mlo mutants are more resistant to P. palmivora and that this effect is limited to meristem-proximal leaf tissues (Le Fevre et al, 2016, MPMI). We have used natural variation in economically relevant cereals to map a quantitative trait locus for leaf resistance in a cross between two barley cultivars. This locus coincides with a segregation distortion locus resulting in skewed F2 populations.
Aim 2. Comparative colonisation process studies in different organs of dicot vs. monocot plants
We have established infection systems for roots and leaves of Medicago, Nicotiana benthamiana, barley and wheat including a range of Phytophthora palmivora isolates with varying aggressiveness. We microscopically assessed infection timing in roots and leaves of N. benthamiana and barley using fluorescently labelled P. palmivora. We carried out dual-RNAseq of infected N. benthamiana roots and barley roots and leaves. We have identified a full set of candidate Phytophthora effectors and their conservation in diverse P. palmivora strains. This is a great research for effector-aided resistance breeding.
Most recently we have identified three SCAR/WAVE genes in barley and delineated their phylogeny. Through collaboration with the team of Matthew Moscou (TSL Norwich) we have generated Cas9-free mutants in each individual gene using CRISPR/Cas9 genome editing. These lines form a foundation for future pathogen, symbiont and development studies to test the feasibility of SCAR/WAVE mutants in quantitative resistance strategies.
We have generated tools (SecretSanta, AMfinder) which will help the transcriptome analyses as well as the semiautomated quantification of fungal colonisation processes in roots. We have provided material and pathogen sequence information to others and have disseminated our findings and approaches on conferences, in seminar presentations, via social media as well as in outreach activities. The team has acquired new skills, network connections and several members were able to move into academic and non-academic positions.
