Tracking effector delivery in Irish famine potato pathogen

Pathogenic microbes interfere with the host cellular and physiological processes to promote infection. This interaction is monitored by pathogen molecules called effectors that either act in intercellular space or enter the host cells. Mechanisms underlying the uptake of these effectors are not fully understood. Oomycete effectors including domain-specific RXLR effectors have provided insights into effector biology over last decade. Even though oomycete effectors have been thoroughly studied as compared to fungal effectors, there has been no clear experimental evidence of their delivery through a particular infectious structure as was shown for effectors of the fungal pathogen M. oryzae several years ago. Now, Wang et al. have clearly shown experimental evidence of RXLR effector delivery through haustoria into plant cells. The authors have traced the localization of a predicted cytoplasmic effector by live-cell imaging using a transgenic strain of pathogen delivering fluorescent-tag fused effector as well as free GFP to track the hyphal growth. This has provided a clear experimental confirmation of RXLR effectors being delivered through haustoria. However, how the effector translocation step occurs still remains elusive and whether the RXLR motif drives translocation remains to be resolved. (Summary by Amey Redkar) New Phytol. 10.1111/nph.14696/full