Understanding plant infection to protect key crops

The latest research from Professor Paul Birch and colleagues has discovered details of how major crop pathogens cause infection. This could provide new ways to control significant diseases that threaten food security.

The work was led by researchers at the School of Life Sciences, University of Dundee and the James Hutton Institute. It focussed on disease-causing oomycete pathogens, such as Phytophthora infestans, the cause of potato late blight. To establish disease, P. infestans delivers virulence proteins called “RxLR” effectors into living plant cells. RxLR effectors target host proteins and processes and manipulate them to suppress plant immunity.

“A key question addressed in our work is: are RxLR effectors taken up into plant host cells by clathrin-mediated endocytosis (CME)?” explained Professor Paul Birch, Head of the Division of Plant Sciences, School of Life Sciences based at the James Hutton Institute.

“We explored whether CME is involved in RxLR effector uptake in two ways. First, we silenced key host components involved in CME and found that both P. infestans infection and RxLR effector delivery into host cells were reduced. Secondly, we immunopurified endosomal vesicles from plant cells during infection and found that RxLR effectors, but not “apoplastic” effectors that function outside of plant cells, were associated with the purified endosomes. This work represents a breakthrough in our understanding of how these RXLR effectors from oomycete plant pathogens enter host cells.”

This research is published in the latest issue of The Plant Cell in conjunction with a second paper from a research group from Kansas State University, showing that fungal effectors are also taken into plant cells via endocytosis. Their work focussed on the fungus Magnaporthe oryzae, the number one pathogen of rice. The journal has selected these two studies for an ‘In brief’ article which summaries both break throughs Knock, knock, who’s there? Two studies provide new insights into the translocation of pathogen effectors into plant cells | The Plant Cell | Oxford Academic (oup.com).

Together, these studies indicate that by understanding how the effectors enter the plant cell, through hijacking host machinery, new avenues to try to control major diseases that threaten food security may be found for important crops.

The research in Dundee was funded by the European Research Council (ERC), but is also supported by Syngenta, who look for new ways to target and prevent diseases such as late blight.