The fungus Plectosphaerella cucumerina is a pathogen of some crops and a model organism for the study of Arabidopsis thaliana basal and nonhost resistance to necrotrophic fungi. In this work, researchers of the Plant Innate Immunity and Resistance to Necrotrophic Fungi group of CBGP have sequenced and compared the genomes and transcriptomes of three Plectosphaerella strains. They demonstrate that the diverse lifestyles and pathogenicity of these strains are determined by the expression of specific fungal and plant genes at early stages of colonization. The Plectosphaerella spp. genomes and transcriptomes described in this article are the first published of this fungal species and also the first genomic project of plant fungal pathogens led by CBGP researchers.
Fungi establish different interactions with plants. Close related fungal strains or species may cause diseases or not depending on their repertoire of pathogenicity mechanisms and on the ability of the plant to defend against colonization. Pathogenic fungi attract much of our attention because they cause important losses in crops and ecosystems. However, non-pathogenic fungi also persist in nature, and they may be able to survive on host surfaces, growing epiphytically and establishing specific types of interactions with plants. Comparing the genomes (repertoire of genes) and transcriptomes (genes expressed) of pathogenic and non-pathogenic fungal strains in their interaction with plants provides cues about the genetic determinants that lead, or not, to disease.
Figure 1. Differential interactions of Plectosphaerella strains PcBMM (pathogenic), Pc2127 (non
pathogenic), and P0831 (epiphytic) with Arabidopsis wild-type plants (Col-0) and immune-deficient
mutants ein2 pad4 sid2 dde2 and cyp79B2 cyp79B3. A, Macroscopic disease symptoms at 7 days
postinoculation (dpi). (B) Heatmaps of gene expression showing the fungal genes significantly up
regulated (log2FC≥2, FDR<0.05) in plants at 10 and 16 hours post inoculation (hpi) in relation to in vitro
growth. (C). Number of in planta expressed fungal genes in the tested conditions and time points. (D)
Validation by qRT-PCR of the expression of some fungal selected genes in plants at different time
Muñoz-Barrios, A., Sopeña-Torres, S., Ramos, B., López, G., Del Hierro García, I., Díaz-González, S., González-Melendi, P., Mélida, H., Fernández-Calleja, V., Mixão, V., Martín Dacal, M., Marcet-Houben, M., Gabaldón, T., Sacristan, S., Molina, A. 2020. Differential expression of fungal genes determines the lifestyle of Plectosphaerella strains during Arabidopsis thaliana colonization. Molecular Plant-Microbe Interactions®. DOI: 10.1094/MPMI-03-20-0057-R