Ash fight back

In the Summer of '76, I spent a few consecutive weeks being a spare wheel in a h u g e field near Arnhem in Nederland Centraal. The Effectives a) planted the field in a randomized pattern of multiple plots each containing 20 genetically identical potato plants b) sprayed the entire field with a uniform fog of late blight Phytophthora infestans spores c) scored each plant {1 to 10}[bloboprev 3rd para] according to how robust was its defense against this not-really-a-fungus scourge . . . after 3, 6 and 10 days. The data, its coding and analysis on a mainframe computer the size of a walk-in closet was an expensive undertaking but it was hoped and expected that the experiment would identify potato cultivars that could be used in subsequent crosses to generate [holy grail] blight-resistant spuds for Europe and the world.

50 years on there is a similar problem with ash die-back where Fraxinus excelsior that wonderful source of hurleys, axe handles, furniture and firewood is on the ropes from being attacked by Hymenoscyphus fraxineus, an ascomycete fungus: characteristic diamond-shaped lesions [R]. Now Dheeraj Rathore of Teagasc has written an RTE Brainstorm describing the fight back by his team at AshForFuture. A key element of that project is to document the variability of response to H. fraxineus among 1,000 genetically variable Irish ash trees. Same principle as my 1976 Potato Summer except that the trial field is in Lithuania where apparently Hymenoscyphus fraxineus spores are on the wind as thick as porridge. Preliminary results indicate that 1% - 3% of the trees are robustly fighting the fungus and remain symptom free. That sort of basic science, data-gathering, infrastructural effort is one boring but necessary requirement for lurching towards an effective solution.

One difference between potato and ash is that the generation time is much much longer in the latter. By the time a trad tree-breeder has done the second back-cross they've been given a clock and sent into retirement. It is timely that, since 1976, science has leapt forward in developing techniques to speed the process of developing designer crops which are vigorous & productive and resistant to a particular disease. Back in 2021, I suggested that anti-microbial peptides AMPs might be the tool to knock ash dieback on the head. That's possibly a case of to a hammer everything looks like a nail having spent 20 years of my research career hunting AMPs in the forests and prairies of genomic sequences.

Our crunching through genomes looking for novel AMPs is another far-from-the-coal-face infrastructural plank to make a functional edifice for fighting disease. Heck we didn't even wear lab-coats while driving our computers. The way forward is clear in theory. All they need to do is sequence the chunks of the ash-genome which are known to carry clusters of plant defensin genes and cross-check the variation against the dieback resistance score. The complete Fraxinus genome has been sequenced multiple times.

By a small-world Irish coincidence, it turns out that me and Dheeraj Rathore are besties co-authors on a paper documenting another genetic tool which can fast-track the delivery of specific genes into specific plants to boost their utility . . .

Years ago, alphaproteobacteria of the genus Agrobacterium were found to be capable of inserting particular genes into a wide variety of plant species. [whoooot GMO alert] Harnessing that ability sure did speed up the process of generating crop plants with enhanced cold-tolerance, disease-resistance and nutritional quality. Teagasc had been developing a different species of alphaproteobacteria called Ensifer adhaerens to carry out gene transfers independent of highly commercialized proprietary Agrobacterium systems. Rathore et al. 2015 was part of young Dheeraj's PhD thesis and my contribution was to supervise an even younger final year undergraduate in a project looking for antibiotic resistance genes in the genome sequence of Ensifer adhaerens.

All the lego bricks are there, still all in a jumble, but GMO ash trees resistant to H. fraxineus are a lot more solid for some science than woolly impractical wishful thinking. What can I do? You can find healthy-looking ash trees in the hedgerows across Ireland and grass them up to the lads at AshForFuture. I know that, come Summer, some of our own many ash will be greener and leafier than others on the same stretch of ditch.