Horizontal gene transfer drives adaptive colonization of apple trees by the fungal pathogen Valsa mali.

Zhiyuan Yin,Baitao Zhu,Lili Huang,Hao Feng

doi:10.1038/srep33129

Zhiyuan Yin, Baitao Zhu + Show 2 more

Open Access

https://doi.org/10.1038/srep33129

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Abstract

Horizontal gene transfer (HGT) often has strong benefits for fungi. In a study of samples from apple canker in Shaanxi Province, China, diverse microbes, along with the necrotrophic pathogen Valsa mali, were found to colonize the apple bark, thus providing ample opportunity for HGT to occur. In the present study, we identified 32 HGT events in V. mali by combining phyletic distribution-based methods with phylogenetic analyses. Most of these HGTs were from bacteria, whereas several others were from eukaryotes. Three HGTs putatively functioned in competition with actinomycetes, some of which showed a significant inhibitory effect on V. mali. Three HGTs that were probably involved in nitrogen uptake were also identified. Ten HGTs were thought to be involved in pathogenicity because they were related to known virulence factors, including cell wall-degrading enzymes and candidate effector proteins. HGT14, together with HGT32, was shown to contribute to bleomycin resistance of V. mali.These results suggest that HGT drives the adaptive evolution of V. mali. The HGTs identified here provide new clues for unveiling the adaptation mechanisms and virulence determinants of V. mali.

Highlights

By combing phyletic distribution-based methods and phylogenetic analyses, we identified 32 Horizontal gene transfer (HGT) events in the apple canker pathogen V. mali
Most of these HGTs were of bacterial origin, and several were of eukaryotic origin
Three HGTs putatively functioned in competition with actinomycetes some of which showed a significant inhibitory effect on V. mali

Summary

Introduction

345 candidates were identified by HGT-Finer, and 32 HGT genes were verified by phylogenetic analyses, manual checking and another phyletic distribution-based method, DarkHorse[14] (Table 1, Supplementary Files). Transcriptomes of V. mali during infection of apple bark, reported by us previously[19], were used to identify HGTs potentially involved in pathogenicity. Six HGTs were strongly upregulated during infection (Table 2), suggesting a potential role in V. mali-apple interaction.

Results

Conclusion