Plant pathogens use effector proteins to target host processes involved in pathogen perception, immune signalling, or defence outputs. Unlike foliar pathogens, it is poorly understood how root‐invading pathogens suppress immunity. The Avr2 effector from the tomato root‐ and xylem‐colonizing pathogen
Humoral and cellular immune responses provide animals with major defences against harmful pathogens. While it is often assumed that immune genes undergo rapid diversifying selection, this assumption has not been tested in many species. Moreover, it is likely that different classes of immune genes experience different levels of evolutionary constraint, resulting in varying selection patterns. We examined the evolutionary patterns for a set of 91 canonical immune genes of North American monarch butterflies (
- NSF-PAR ID:
- 10367338
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 30
- Issue:
- 18
- ISSN:
- 0962-1083
- Page Range / eLocation ID:
- p. 4381-4391
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Apicomplexa are ancient and diverse organisms which have been poorly characterized by modern genomics. To better understand the evolution and diversity of these single-celled eukaryotes, we sequenced the genome of
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Abstract Pathogen pressure on hosts can lead to the evolution of genes regulating the innate immune response. By characterizing naturally occurring polymorphisms in immune receptors, we can better understand the molecular determinants of pathogen recognition. ZAR1 is an ancient
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Abstract Background Fungal plant pathogens have dynamic genomes that allow them to rapidly adapt to adverse conditions and overcome host resistance. One way by which this dynamic genome plasticity is expressed is through effector gene loss, which enables plant pathogens to overcome recognition by cognate resistance genes in the host. However, the exact nature of these loses remains elusive in many fungi. This includes the tomato pathogen
Cladosporium fulvum , which is the first fungal plant pathogen from which avirulence (Avr ) genes were ever cloned and in which loss ofAvr genes is often reported as a means of overcoming recognition by cognate tomatoCf resistance genes. A recent near-complete reference genome assembly ofC. fulvum isolate Race 5 revealed a compartmentalized genome architecture and the presence of an accessory chromosome, thereby creating a basis for studying genome plasticity in fungal plant pathogens and its impact on avirulence genes.Results Here, we obtained near-complete genome assemblies of four additional
C. fulvum isolates. The genome assemblies had similar sizes (66.96 to 67.78 Mb), number of predicted genes (14,895 to 14,981), and estimated completeness (98.8 to 98.9%). Comparative analysis that included the genome of isolate Race 5 revealed high levels of synteny and colinearity, which extended to the density and distribution of repetitive elements and of repeat-induced point (RIP) mutations across homologous chromosomes. Nonetheless, structural variations, likely mediated by transposable elements and effecting the deletion of the avirulence genesAvr4E ,Avr5 , andAvr9 , were also identified. The isolates further shared a core set of 13 chromosomes, but two accessory chromosomes were identified as well. Accessory chromosomes were significantly smaller in size, and one carried pseudogenized copies of two effector genes. Whole-genome alignments further revealed genomic islands of near-zero nucleotide diversity interspersed with islands of high nucleotide diversity that co-localized with repeat-rich regions. These regions were likely generated by RIP, which generally asymmetrically affected the genome ofC. fulvum .Conclusions Our results reveal new evolutionary aspects of the
C. fulvum genome and provide new insights on the importance of genomic structural variations in overcoming host resistance in fungal plant pathogens.
