Effector-triggered defence: A new concept in plant pathogen defence

In June, a team of Brassica researchers from the University of Hertfordshire proposed a new classification for a type of plant defence mechanism: effector-triggered defence (ETD).

Henrik Stotz is first author of the paper describing ETD, currently In Press in Trends in Plant Science. He explains, “In the same way that humans have developed immune responses against human disease pathogens, crops can be bred for resistance against disease pathogens, but we need to improve our understanding of effective resistance mechanisms within plants. Our research enhances the traditional understanding of the plant defence system and describes a new concept, which is how plants protect themselves against the pathogens that grow in the space outside plant cells (the apoplast) – a new concept called effector-triggered defence or ETD.”

Traditionally, plant pathogen defence is broken into two broad forms: pathogen-triggered immunity (PTI) and effector-triggered immunity (ETI). PTI is the first action the plant takes against a pathogen and is triggered when the pathogen lands on the plant. The pathogen releases molecules called effectors into the plant cells, which the plant recognises and reacts against. If the effectors are not recognised, the pathogen can spread with little resistance.

The team from Hertfordshire, led by Bruce Fitt, argue that one line of defence, R gene-mediated host resistance against fungal pathogens that grow in the space between cells, is not adequately explained by either mechanism.

Effector-triggered defence (ETD) is mediated by R genes encoding cell surface-bound receptor-like proteins that engage the receptor-like kinase SOBIR1 – an extracellular recognition. The response is host cell death after an extended period of endophytic pathogen growth. This is in contrast to ETI, in which detection of the pathogen occurs within cells and usually triggers fast host cell death.

ETD is described in Stotz et al. (In Press) Trends in Plant Science DOI: http://dx.doi.org/10.1016/j.tplants.2014.04.009

The quotes used in this article are from this BBSRC Press Release. This story was originally posted on the UK Brassica Research Community website.

 

ADAS Boxworth Open Day

Categories: guest blogger
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Published on: June 26, 2014

Charlotte White, crop physiologist at environmental and agricultural consultancy ADAS, reports from the ADAS Boxworth Open Day where science from ADAS is showcased alongside work funded by Defra and HGCA as well as private enterprises. It is a great opportunity for scientists, agronomists, farmers and seed/agrochemical representatives to network and discuss their needs and current work.

adas boxworth

On the 3rd of June ADAS Boxworth in Cambridgeshire opened its fields to welcome around 200 visitors. The rather wet morning, which made the behind the scenes setup soggy, dissipated in time for the mid-day opening and the afternoon was lovely and sunny. Visitors included farmers, agronomists, members of the seed and agrochemical industry, students and the farming press.

On arrival visitors were welcomed with a complementary hog roast and could register for BASIS and NRoSO points. At reception there was a demonstration of electrical weeding, which had a lot of interest, along with updates on the SCEPTRE project, the fertiliser value of anaerobic digestate and the HGCA stand. There were then two routes: wheat followed by oilseed rape or oilseed rape followed by wheat. The majority took the latter.

The oilseed rape field had a number of Defra, HGCA and commercially funded project demonstration plots. These included optimising seed rates/row widths, and the project I was demonstrating, which looks at precision applications of late foliar nitrogen fertiliser to increase yield and feed value of the rape-meal (CC: described in this UKBRC factsheet). Dr Steve Ellis spoke about pollen beetle thresholds and neonicotinoids, while Dr Faye Richie was on hand to answer questions on oilseed rape diseases relevant to this season and give updates on the latest findings from the pathology group. The industry variety and product demo plots appeared to have a high yield potential and formed the perfect environment to catch up with sponsors and collaborators. As you turned the corner in the field it was a surprise to find Ken Smith stood in a soil pit promoting good soil management on behalf of HGCA, a topic which always generates a lot of interest and gets people talking!

The wheat field was across the farm road and had a similar mix of government, levy and industry funded project demonstration plots, industry stands and variety and product plots. Prof Roger Sylvester-Bradley explained the yield enhancement network (YEN), an innovation competition to help growers break existing cereal yield records. The demonstration plots, testing ‘innovative ideas’ to maximise grain filling, included irrigation, reflective soil strips and plot cooling (if you are interested in entering the YEN competition, visit the website). The triticale demo plots also received a lot of attention and Dr Sarah Clarke and Dr Daniel Kindred were on hand to discuss the benefits of triticale – it out-yields wheat as a second cereal – and to promote the LearN project, which is using a novel on-farm approach to investigate nitrogen monitoring and management. Jonathan Blake was there to discuss the HGCA Fungicide Performance work, and had some interesting demonstration plots to show yellow rust and septoria tritici control. In addition to these and other interesting research demonstration plots, national ADAS experts in weed, pest and disease management were around to answer all manner of questions. Visitors were kept lingering long after the 4pm close.

For me, it was a long and invigorating day and great to talk to farmers and agronomists about their experiences with late application of foliar nitrogen and to provide an update on the latest project findings, as well as seeing what everyone else in ADAS has been working on. Don’t worry if you missed it, keep your eye out for flyers for future open days!

Image credit: Charlotte White

UK Brassica Research Community

Categories: Brassica
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Comments: 1 Comment
Published on: March 7, 2013

Brassica crops, which include oilseed rape, cabbage, and brussels sprouts, are major components of the UK arable agriculture and horticulture industries. The close relationship between Brassica and Arabidopsis provides exciting opportunities to translate fundamental science to impact by using it to understand and manipulate crop traits.

If you are interested in finding out more about Brassica research and the UK Brassica research community, come to the annual meeting of the UK Brassica Research Community at Rothamsted on 9 May 2013.

A successful UK brassica industry requires fundamental and applied scientists, breeders, and farmers to work together. The UKBRC provides a hub for them to do so. Everyone can catch up at the annual meetings, but for the rest of the year check out the UKBRC website and join the UKBRC mailing list to get news and find resources.

You can register for the event here, and see talks from previous meetings on the UKBRC website. If you currently work with Brassicas and would like to share your research at the meeting, contact Pierre Carion (pierre.carion@rothamsted.ac.uk) to find out more.

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