Plant and tree "vaccination"

[Dave2002]

Since the announcement about ash die back recently, I wondered if trees can be vaccinated, and if they have any kind of immune system. Seems they don't have anything which works in quite the same way as animals, but they do have some defences.

This article is interesting - http://www.nature.com/nature/journal...ture05286.html

[doversoul1]

I suppose the problem of vaccinating trees is, unlike cattle, few people have vested interest. I have not read the article thoroughly but as it mentions the crop, I imagine this is more for the interest of forest industry (not sure about the term). I love the ash trees in my garden, dozens of them, and would be very sad if they died but I doubt if I could afford the time and cost of vaccinating them. Very worrying indeed.

How come we import ash trees?

[Pabmusic]

Part of the answer is contained in the article: "Plants ... lack mobile defender cells and a somatic adaptive immune system". In other words, no equivalent of white blood corpuscles, which can 'pick up' antibodies and deliver them anywhere in the organism. This would make anything like vaccination very difficult to achieve, since vaccination relies on the preservation of antibodies as a central resource. Presumably, it was too costly for evolution to develop a system for plants that was similar to that in animals (not that anything ever did a cost-analysis, of course)..

[umslopogaas]

I ought to be more confident in answering this question than I am, but I'll have a go. Plants do have chemical responses to infection. For example, pines react to infection by surrounding the infected tissue with a zone of substances called pinosylvins, which inhibit fungal growth and may seal off the infection. It would I think be possible to challenge (ie vaccinate) a tree with an attenuated strain, or maybe a related but non-pathogenic species and thereby build up levels of antagonistic chemicals. The problem, and the reason this isnt done, is as outlined in the above post. Plants do not have an equivalent of the mammalian circulatory system and have no equivalent means for distributing their antibody equivalents.

But ... I detect memories of school biology lessons ... plants have xylem, which conducts water up from the roots to the leaves, and phloem, which conducts soluble sugars from the leaves downwards to the roots. So actually plants do have a conducting system. Yes, but the reactions that produce antibody equivalents dont take place in those conducting systems, but in adjacent tissues, and there is no mechanism to gather them up and move them around in the xylem and phloem.

Given that there is no effective mechanism for redistribution, if you wanted to "vaccinate" a plant, you'd have to somehow cover it in sufficiently numerous "vaccination" sites to give adequate cover. On a large tree this would be thousands, and is completely impractical, even assuming the appropriate vaccine, and mechanism to deliver it, could be found.

No, I'm afraid we are going to have to get used to a lot less ash. On the brighter side, as mentioned before, I think DEFRA are right to be hopeful of finding a few resistant survivors among our genetically heterogeneous population, from which we can repopulate. And that, incidentally, is probably why we need to import ash trees: such selection for resistance would already have occurred on the continent and we could speed up recovery by importing resistant trees.

I'm a bit uneasy about that reply, but I'll offer it anyway. Time was when I had a shelf full of books to check details, but I've been retired now for five years, I sold off the texts and memories fade.

[amateur51]

I ought to be more confident in answering this question than I am, but I'll have a go. Plants do have chemical responses to infection. For example, pines react to infection by surrounding the infected tissue with a zone of substances called pinosylvins, which inhibit fungal growth and may seal off the infection. It would I think be possible to challenge (ie vaccinate) a tree with an attenuated strain, or maybe a related but non-pathogenic species and thereby build up levels of antagonistic chemicals. The problem, and the reason this isnt done, is as outlined in the above post. Plants do not have an equivalent of the mammalian circulatory system and have no equivalent means for distributing their antibody equivalents.

But ... I detect memories of school biology lessons ... plants have xylem, which conducts water up from the roots to the leaves, and phloem, which conducts soluble sugars from the leaves downwards to the roots. So actually plants do have a conducting system. Yes, but the reactions that produce antibody equivalents dont take place in those conducting systems, but in adjacent tissues, and there is no mechanism to gather them up and move them around in the xylem and phloem.

Given that there is no effective mechanism for redistribution, if you wanted to "vaccinate" a plant, you'd have to somehow cover it in sufficiently numerous "vaccination" sites to give adequate cover. On a large tree this would be thousands, and is completely impractical, even assuming the appropriate vaccine, and mechanism to deliver it, could be found.

No, I'm afraid we are going to have to get used to a lot less ash. On the brighter side, as mentioned before, I think DEFRA are right to be hopeful of finding a few resistant survivors among our genetically heterogeneous population, from which we can repopulate. And that, incidentally, is probably why we need to import ash trees: such selection for resistance would already have occurred on the continent and we could speed up recovery by importing resistant trees.

I'm a bit uneasy about that reply, but I'll offer it anyway. Time was when I had a shelf full of books to check details, but I've been retired now for five years, I sold off the texts and memories fade.

Many thanks for this, umslopogaas not least for resurrecting my memories of xylem and phloem - they are two cracking Scrabble words

[Pabmusic]

...No, I'm afraid we are going to have to get used to a lot less ash. On the brighter side, as mentioned before, I think DEFRA are right to be hopeful of finding a few resistant survivors among our genetically heterogeneous population, from which we can repopulate. And that, incidentally, is probably why we need to import ash trees: such selection for resistance would already have occurred on the continent and we could speed up recovery by importing resistant trees.

I'm a bit uneasy about that reply, but I'll offer it anyway. Time was when I had a shelf full of books to check details, but I've been retired now for five years, I sold off the texts and memories fade.

A really good post. Yes, there will almost certainly be survivors among the ash population, which should produce a resistant strain (with a little help from man) in a reasonable time. But none of us reading this will ever see again what we have grown up with.

[Dave2002]

There is a substance called Dutch Trig which is used to treat elm trees. The suppliers seem to call it a "vaccine" but whether it really is I couldn't say. However there does seem to be some evidence (or am I just being taken in by the hype?) that it works. http://www.dutchtrig.com/

[LeMartinPecheur]

There is a substance called Dutch Trig which is used to treat elm trees. The suppliers seem to call it a "vaccine" but whether it really is I couldn't say. However there does seem to be some evidence (or am I just being taken in by the hype?) that it works. http://www.dutchtrig.com/

How many elms have we got these days? Did resistant trees survive here in any numbers? Did any areas avoid infection?

[I have tried googling for this info but for some reason my system doesn't seem to be letting me this morning]

[Pabmusic]

How many elms have we got these days? Did resistant trees survive here in any numbers? Did any areas avoid infection? ...

I found this, which says 1 tree in 100,000 was immune, and that experiments are taking place to clone them (though why they don't just breed them, I don't understand).

http://www.dailymail.co.uk/sciencetech/article-2122617/Could-elm-trees-return-landscapes-Scientists-clone-1-100-000-trees-resist-Dutch-Elm-Disease.html

[Bryn]

This was last updated 4 years ago.

There is also the Dutch Elm Disease Management Area in Sussex.

[umslopogaas]

Many elms survive, but only as hedgerow trees. They get to a height of about twenty feet, which is the height at which the beetles which vector the disease fly. The beetles then find them, feed on the bark and infect the wood with the disease. The trees then die back, but suckers survive and grow back again.

There are some exotic elms which have resistance to the disease, but they dont look much like the native ones we have lost.

For a long time Brighton and Hove retained a lot of mature elms, because they are effectively an island, with the sea on one side and elm-free Downs on the other three. The Downs were too large for the beetles to cross, so the trees were not attacked. I think I heard that recently the disease had arrived, but it may be possible to eliminate it if they are ruthless about cutting out the infected trees, although in practice this may be difficult if the trees are privately owned.

That website for Dutch Trig is most interesting, they seem to have developed a kind of vaccine along the lines I suggested earlier. I hadnt previously heard of it. The strain of Verticillium albo-atrum is too attenuated to be pathogenic, although normally that fungus is a pathogen and does cause wilt. Incidentally the epithet "Dutch" is rather unfair on the Dutch, it sort of implies Dutch Elm Disease is their fault, but in fact its called "Dutch" because much of the early research on it was carried out in the Netherlands.

I expect they've tried it on ash dieback, but since ash is a different species, the strain might not be attenuated enough (the host range of V. albo-atrum is very wide) and they will probably need to find a new strain.

[vinteuil]

A really good post. Yes, there will almost certainly be survivors among the ash population, which should produce a resistant strain (with a little help from man) in a reasonable time. But none of us reading this will ever see again what we have grown up with.

The great elms were very much a feature of the west Wilts landscape where I grew up; I still miss them very much when back in them parts.

I know the ash tree is important in numbers, and also significant culturally for its celtic and druidic resonances. But I have to confess that I'v never found it a particularly handsome tree (yes, appalling anthropocentric aesthetic judgment here, I know): so, sad, but - selfishly speaking - I won't miss them as much as I miss the elms...

[Lateralthinking1]

We have heard quite a bit about natural selection.

Can someone advise please how many times between, say, 1800 and the 1970s up to 95% of a certain kind of tree died from this kind of disease.

[Serial_Apologist]

We have heard quite a bit about natural selection.

Can someone advise please how many times between, say, 1800 and the 1970s up to 95% of a certain kind of tree died from this kind of disease.

Not in my case, Lat.

That said, I would imagine that scientists across disciplines should be investigating possible effects from global warming in this instance. Not much has been said or written as far as I know on such a connection - I imagine someone here would have referred to links. Species demise can be as much brought about by for example fungoid infections whose genesis could be ascribable to climate change - not just temperature rises, but shifts in prevailing wind directions leading to importations of infections "awaiting" suitable hosts, changes in humidity, and so on - and we know that temperature increases over the period since the Industrial Revolution have been unprecedented.

I'm only guessing here, mind!

[umslopogaas]

Lateralthinking1, there have certainly been many epidemics of introduced diseases in the last two hundred years, but not all diseases are fatal. One that is, and is devastating the Australian ecosystem, is Phytophthora cinnamomi. This kills not only eucalyptus, but much of the associated flora in eucalyptus forests. It is not thought to be native to Australia.

One that is not fatal, but serious and damaging is coffee rust (Hemileia vastatrix), which has now spread to all major coffee growing areas. Coffee is a high value crop and rust can be controlled by spraying, at a price.

A pest, rather than disease, which has now spread through most of the UK after arriving from the continent a few years ago, is horse-chestnut leaf miner, whose Latin name I have temporarily forgotten (Somethingorother ohridella). It isnt fatal, but it does make a mess of the leaves by the end of summer.

Cameraria ohridella, that's it.

And a disease we dont yet have, which would be serious and which the Forestry quarantine people are determined to exclude, is sweet chestnut blight (Cryphonectria parasitica). It has seriously damaged sweet chestnut in north America and much of Europe. Another is oak wilt (Ceratocystis fagacearum) which damages oaks in north America and would be potentially devastating if it got to the UK.

The story of the Dutch Elm Disease epidemic is quite interesting (well, to pathologists, anyway). Before the second war there was an outbreak of disease on elms, caused by what we now know was the fungus Ceratocystis ulmi (unless the taxonomists have changed the name, I sometimes think they change the names of fungi more often than they change their shirts). This was not terribly damaging, and by the time the war was over and people were looking at trees again, it ceased to cause any concern. Since we knew we had the pathogen already, we began importing elm logs from the USA (not sure why when we had plenty of elm of our own, but maybe the US material had some superior properties). We knew that there was elm disease in the USA, but since we thought we already had the same pathogen, no-one cared much about the bother of quarantine. As a result, the north American pathogen duly arrived in the UK on imported logs. Unfortunately, it turned out it wasnt the same pathogen, but a new and much more virulent one, which we had not encountered before. And that was pretty much the end of the elms as a feature of the landscape. The new pathogen was eventually named Ceratocystis novo-ulmi. You live and learn.

To answer the question, Sweet Chestnut Blight, Oak Wilt and Phytophthora cinnamomi have all caused serious or devastating damage.

Oh, and coffee rust wiped out the coffee in Sri Lanka in the 19th century, which is why they switched over to tea.