Abstract
Hosts and pathogens typically engage in an evolutionary arms race. This also applies to phytopathogenic powdery mildew fungi, which can rapidly overcome plant resistance and perform host jumps. Using experimental evolution, we show that the powdery mildew pathogen Blumeria graminis f.sp. hordei is capable of breaking the agriculturally important broad-spectrum resistance conditioned by barley loss-of-function mlo mutants. Partial mlo virulence is associated with a distinctive pattern of adaptive mutations, including small-sized (8-40 kb) deletions, one of which likely affects spore morphology. The detected mutational spectrum comprises the same loci in at least two independent mlo-virulent isolates, indicating convergent multigenic evolution. This work highlights the dynamic genome evolution of an obligate biotrophic plant pathogen with a transposonenriched genome.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Abbreviations
- Bgh
- Blumeria graminis f.sp. hordei
- bp
- base pair
- dpi
- days postinoculation
- hpi
- hours post-inoculation
- LINE
- long interspersed nuclear element
- LTR
- long terminal repeat
- Mla
- Mildew resistance locus a
- Mlo
- Mildew resistance locus O
- MMEJ
- Microhomology-mediated end joining
- NHEJ
- Non-homologous end joining
- PCA
- principal component analysis
- PCR
- polymerase chain reaction
- PEN1/2/3
- PENETRATION1/2/3
- RH
- relative humidity
- RNA-seq
- RNA-sequencing
- Ror1/Ror2
- Required for mlo-specified resistance1/2
- qRT-PCR
- quantitative reverse transcriptase-polymerase chain reaction