Ever wondered how endophytes benefit the grass in which they live or how they affect the animals grazing on them?
Al Moorhead and Glenn Judson are here to fill in all the gaps; from just what endophytes are, what they mean to New Zealand, how they pass through generations of ryegrass and how they help with various pasture pests.
Endophytes are a vital tool in many farmers' toolboxes, so make sure to listen in!
“What that has highlighted is that endophyte has been a very special thing.”
Juddy In this particular episode Allister, what are we going to be talking about?
Al Well, Glenn, we're going to be discussing one of nature's wee gems, which is the natural relationship between a fungus called endophyte and perennial ryegrass or ryegrass. And you know, what we're going to cover is, you know, what is an endophyte? We're going to cover, you know, what are the critical advantages of having endophyte in different parts of the country and where it comes in. And we can discuss some of the types of endophytes that Agricom works with inside their genetics. And by the end of that, we'll probably touch on a couple of other quirks of having this relatively complicated system inside the New Zealand farming world. And I think that would cover us for what is quite a technical topic. We'll try to keep it at quite a high level.
Juddy Okay, cool. So I guess the first thing and we hear this a lot in terms of we were going to order seed and the discussion about endophyte comes up. Let's go really basic here and go what in fact, is an endophyte and what's the symbiotic relationship?
Juddy That’s the one. What relationship does it have with the plant?
Al Well, Glenn, it looks like ryegrass as it escaped from the last Ice Age travel right across Europe from what was a very small area where it survived and as it moved out across Europe, particularly around the Mediterranean, it obviously encountered more and more stressful situations, both in landscape types and dry areas and in different environments where there were a lot of different insect pressures. And it would appear at some point in some time a small fungus made it into ryegrass seed and found a pretty happy place to live. And in doing that, naturalised and ryegrass seed and formed a symbiotic relationship where, you know, I think you describe it really nicely, but that's basically where one thing lives with another thing which provides it with all its resources, but then it provides an advantage for its host. So it's a win-win situation.
Juddy Yeah. So so I guess what we're talking about here is this fungus, which the ryegrass plant hosts, gives it a place to live, supplies it with nutrients and the symbiosis. In return, this fungus is producing some alkaloids which give a level of protection against insect feeding and stressful situations, potentially even grazing by herbivores. So quite a strong, and you can see it from an evolutionary point of view, plants that are able to host these particular endophytes, probably have an advantage and as we move to stressful situations and we have more bugs and more grazing herbivores.
Al Absolutely. And so, you know, the history of endophyte in New Zealand fundamentally is that a lot of our seed came from the UK and the early days of planting our ryegrass landscape, and it would appear that we introduced only one endophyte. Now getting back to what is endophyte, though, is that is a small fungus that lives intercellular and the basal area of a ryegrass plant, and it carries out its life cycle by living in the basal area of the plant and as a ryegrass plant goes to its reproductive phase, puts up a seed and creates its seed the endophyte mobilises, travels up the steam and colonises the new generation of seed. Now it's a living organism and if the endophyte ever dies, it can never be reintroduced naturally. It can be, you know, we've discovered technology for inoculating plants that don't have endophyte and I'll explain that shortly. But the reality is it's a living organism, it is either in the plant or it's not. And when it's not, it cannot come in from any other way other than this natural process of moving from a fully infected plant up the stem into the new generation of seed and into the next cycle.
Juddy So just to clarify, it doesn't come through pollen?
Al It doesn't come through pollen, and it cannot move through the soil into the plant. So it's quite an important acknowledgement. It's a living combination and really has to be because of that. It's actually a little bit complicated in looking after it and making sure it does work properly, the biological system of it, moving into the seed, living in the seed, moving out into the next generation is actually a biological system that we have to work with quite closely in this day and age.
Juddy And I guess the other bit that's probably, and you're probably going to come to this, but to point this out is that we talk about endophyte as a singular thing. But actually, there are a number of different types of endophyte
Al And that's exactly what I was getting onto Glenn because when we got our original seed lines out of the UK, only one endophyte made it to New Zealand. And that endophyte we describe as a standard endophyte or traditional endophyte. And there's a few alkaloids in these plants and in this particular endophyte that colonised all of New Zealand up until the mid-90s, in every grassland in New Zealand, had the alkaloids peramine, loletrim b and ergovaline. And we will touch on what some of these different alkaloids mean later, but this is the discovery of endophyte in New Zealand is only as recent as the late 70s, early 80s, and it was almost by accident. And that's a story for another day with a slightly older person than myself, but it is really fascinating that is actually a recent discovery. And then for all the 80s and during the end of the 80s, there were discoveries that around the world, not all the endophytes were the same. And this was important because, in this old traditional standard endophyte, it's the same endophyte that still exists in the variety Nui. And it's part of its population, half of its seed mostly has no endophyte, but some of the seeds still have this particular style, and that is it creates some of those alkaloids, particularly loletrim b is a mammalian toxin and can create staggers, dags and a few things through the summer, with very high levels of ergovaline, create animal health and ill-thrift through the summertime. Now we faced this throughout all of New Zealand up until the mid-90s, but in the late 80s and mid-80s to late 80s, AgResearch particularly discovered that this was not the only endophyte that existed in ryegrass around the world, and they tracked a large number of different styles that produced different amounts of alkaloid. And the discovery of novel endophytes came about pretty much through the end of the early 1990s, with the first new endophyte being commercialised in 2000, which was AR1, which was the first what you would describe as fully animal safe endophyte and the alkaloids that only affected insects were the ones there and it didn't produce the alkaloids that affected the animals.
Juddy And I think I can remember the release of that and there was a lot of excitement around the fact that we now had an endophyte that provided some protection and we came later to discover that it wasn't full protection, but it gave partial protection to the plant, but actually almost none of the downsides of the standard endophyte from an animal perspective. So it was exciting in the fact that we now had a safe endophyte for animals.
Al And we did learn of things like you just said, you know, when you take out all the protection mechanisms from the animal, it means as a farmer you have to up your management because you have to now be careful with your grazing residuals. Whereas before the alkaloids and the base of the ryegrass plant were protecting the plant from you overgrazing with your animals, they started to stagger and therefore you stopped grazing so hard under dry conditions. Now, once that protection was removed, the onus came back onto you as a farmer and a farm manager to not overgraze your pasture, not overgraze your pasture during droughts or stress. And so that's where some of the AR1 endophyte in more stressful environments actually started to struggle with persistence because once we took away one of its true prediction mechanisms, it became all about you and your management. And individually, you know, as I've commonly said, as you know, I want to try and find as many combinations where we don't have to manage especially. But when it comes to overgrazing and stressful conditions, it's always been an advantage if the plant protected itself and when we remove that, it's up to you to protect the plant. And sometimes you're stressed and you don't always get it right, and therefore you overgraze and next thing, you're in a declining situation. So that was the emergence of novel endophytes. But the endophyte story is unique to New Zealand, and it's because we're an island and because we're an island, an island nation and quite remote, and most of these things are introduced, what has actually happened is the pasture pests that have come into New Zealand over time have absolutely thrived in our temperate environments. And this is the reason endophyte means more to New Zealand than virtually anywhere else in the world. One ryegrass is just that important to the New Zealand economy, it's worth I believe close to $14 billion of economic return to the New Zealand economy can be attributed to ryegrass based pastures and ryegrasses. So it is a really important species, however, because we're an island when the pasture pests have either the some of the native insects that have adapted to eating ryegrass really successfully or introduced pasture pests have come without their controls. Suddenly endophyte has become more important than New Zealand to anywhere else in the world and it's become really interesting.
Juddy So that's a really important point, I guess, if we look from a New Zealand centric point of view, you know, we've always had endophyte, whether that be standard endophyte or now with some of these novel endophytes. But actually, that's quite unique in the world and if we travel to other countries in terms of their agricultural industry endophyte is not something that they are familiar with.
Al No, because the pests that have travelled to New Zealand have no natural biocontrols, but in their homelands, they have multiple controls, so they never form these massive populations that can devastate pasture. Whereas over here, when they have no natural control processes, they can build to levels pretty much unseen anywhere else in the world. And therefore, actually anything that provides an advantage to the plant is gold. Particularly when you're trying to develop a sort of resilient and persistent system. So I think that's a big driver to true success.
Juddy So we get to the point now where we've got this AR1 and we've got a complete animal safety as long as we are managing it well, we're able to get some persistence out of that. What happens next?
Al Well, from our perspective, another endophyte emerged in our world in the 90s and we didn't even know what was creating the changes in the plots. And this shows you how new endophyte is. But this endophyte existed. It had a new set of chemistry, we've mentioned alkaloids peramine, loletrim b, ergovaline, which are common pathways in a lot of the endophytes we work with. And the novel endophytes are of the same just sort of genetic base, and they just have pathways that don't complete and don't become the final alkaloid. But a completely new alkaloid emerged that we didn't know what it was to know what it meant. We didn't know a lot about it until plots in the 90s were starting to be seen in dry environments that were completely green. While all the rest of the plots and...
Juddy And really interesting, the fact that got overlooked was because a lot of the researchers were looking for those normal alkaloids.
Juddy Because it was low in those or had none of them, that plant was overlooked, whereas,
Al or we just didn't know what it meant.
Juddy Yeah, but in the plots when we started growing this, these were outstanding and so I guess that led to the discovery of some of these intermediate alkaloids, not the full pathway, but somehow
Al the epoxyjanthrims as a completely different alkaloid profile and so it's a completely different scenario. But the point being is AR37 emerged out of that discovery and that has a completely different alkaloid that protects itself in the plant, and it's a group of epoxyjanthrims. So the key really here is that’s what made the plot green. And it was the alkaloids that were there impacting a pasture pest that we didn't even acknowledge at that time. So here's an example where something as recent as the 90s, there is a pasture pest that feeds on the roots of ryegrasses that we weren't even acknowledging as a pasture pest.
Juddy And what's that?
Al It was called root aphid. So root aphid is a robber that robs the plant of energy like an aphid on a rose, aphid on your vegetables, aphids on your crops. It is sucking a plant under stress, and in this case, there are aphids in the roots of your pasture. And the reality is, it turned out the epoxyjanthrims were very good at protecting against root aphid, which creates this greening in summertime when aphids are obviously putting a lot of pressure on the root structures. So that leads really to the group of insects that endophytes can impact in New Zealand because, as I said, you can't talk about why endophytes are important without acknowledging New Zealand's really special for the very destructive pests for the survival of ryegrass. And so, for example, in the warmer winter environments of New Zealand, which the areas spreading, of course, with the slow climate change. But African black beetle has found a home in the north of New Zealand and slowly down the coasts of the west coast of the North Island and it's moving slowly into the Hawke's Bay and there are even small populations up in the Golden Bay area of the South Island and that pasture pest is quite devastating for the perenniality of ryegrass, partly because the only mechanism we have to protect the ryegrass is to have the alkaloids present that stop the female black beetle from staying in your paddock. So if it eats a leaf of a plant infected within the endophyte and the right endophytes with the right alkaloids that black beetle will say "I can't be here, this is not what I want to eat, I don't want to stay here" and it moves on. It goes and infests another paddock, possibly an annual ryegrass paddock or a paddock where the endophyte doesn't match the pest, in this case, African black beetle, and she is able to eat, but once she lays eggs in the paddock. No perennial ryegrass endophyte is able to protect the roots of perennial ryegrass from the very large lava that come and the larval phase of the black beetle. So it's a very devastating pest. The adult is quite devastating on establishing new pasture. But the larvae can wipe out anything. So the best mechanism we have is to tell the female to go away and go and find something to eat. There's a common theme here because that's a trait that endophyte does a lot. It tends to try to be a feeding deterrent
Juddy And therefore reduce the amount of egg that's being laid.
Al And so the other big pasture pest that is that and ARI, is a really good example of this is Argentine stem weevil. And the weevil itself can only destroy tiny seedlings and the adult weevil is a pest of establishing pasture. Once established, the adult weevil can't really damage, it's too small to damage the foliage enough of a perennial ryegrass plant to destroy it. However, it lays its eggs in the tillers of ryegrass plants. And that's why it's called Argentine stem weevil. The larvae tiller and bore through the tillers, and they actually kill the tillers. And of course, multiple leaves are formed from the tillers, and then they just die, basically. The central leaf turns brown, there's a hole in the bottom and it's physically chiselled out the inside. Technically, they need about four tillers to go through their life cycle.
Juddy And so while the adult is unlikely to be able to damage an establishing pasture
Al an established pasture,
Juddy so the larvae are certainly devastating, particularly to young pastures.
Al Yeah. So what's really interesting is AR1 is very good for Argentine stem weevil. It's not good for African black beetle, very good for Argentine stem weevil. However, AR37 has a different mechanism for Argentine stem weevil and it doesn't deter the female. So AR1 deters the female, she goes away and lays in a paddock of Italian ryegrass. AR37, she doesn't get deterred at all and she lays eggs in AR37 based pastures. However, the alkaloids that are cycling with AR37 kill the larvae so before they can physically damage the tiller as a young larva just emerging, trying to chew into it they are killed. So it's a really effective mechanism for absorbing a lot of eggs in a population and then killing the larvae. And it's quite a good integrated pest management almost for winding down Argentine stem weevil using the AR37 endophyte. Then we've got other insects that are big players, and one of them is porina. That is a native moth that flies into pastures with high cover, lays its eggs, and those caterpillars are developing through autumn into winter, and some of the late flights all the way in through to August/September. Now, no endophytes really protect against those to any degree other than AR37 and AR37 is not a complete protection against porina, but can protect very effectively against the flights that hatch in autumn and create damage in May and June. The alkaloids are still in high enough amounts in that late autumn phase when the larvae are small, that they are quite toxic to those larvae and it can really reduce the damage of porina in that window of time. However, some of those species of porina lay quite late. They hatch very late and the environment's much cooler and the alkaloid levels are lower and they are far less effective at controlling it. But as far as porina goes, AR37 is the most effective endophyte for controlling that insect pest. After that, it gets really tough because those three I've just described are the big three for truly destroying pasture. We've discussed the root aphid, which is just a robber of dry matter production at times of stress. So having resilience during times of stress is still highly attractive and that's what makes AR37 quite special in summer conditions. But one of the big ticket items that ryegrass has never been able to be tolerant of is the native New Zealand grass grub. And that is another very big ticket insect pest, which currently there are no perennial ryegrass based endophytes to tolerate that.
Juddy So, so just on that and probably just stretching a little bit outside endophyte, if you were in, you know, in the ryegrass/grass grub zones, what's something that you can do that might help that situation? Obviously, you said, there's nothing we can do in the endophytes. Is there anything that we can do in terms of maybe species selection or management? What are the, in terms of some hope in those grass grub zones?
Al Well, because we're talking about endophyte and perennial ryegrass, there's not actually a lot of hope. It's been definitely a massive target of the industry to find a solution in such a flexible species, a highly nutritious plant that grows in autumn and winter and can take a lot of different managements and is described as very, very user friendly. There's no easy answer to grass grub that's going to be solved in the short term by endophyte in perennial ryegrass. Glenn, to answer that, really, we are stepping out of this conversation and heading towards the world of tall fescue, particularly tall fescue and in recent times, Agricom has started commercialising a meadow fescue and meadow fescue has an endophyte that's moderately, you know, quite functional when it comes to grass grub, but meadow fescue itself is not a complete grass. It is probably not capable of being a driver of a farm system by itself, it only grows about seventy-five per cent of what a perennial ryegrass cane has got really weak shoulders through the winter it's dormant and it likes high fertility situations. There are other things that drive its success other than grass grub. So we've got some mechanisms there to go to. They have actually always been here and if someone's desperate enough to try tall fescue and in recent times, Agricom's been testing the tall fescue/meadow fescue mixes. And we believe, you know, they are an intermediate scenario where you've got resilient pastures that can be managed easier because meadow fescue is high quality and helps grazing management. They are a little bit of a solution, but not really in the ryegrass world. There's not a lot in that space.
Juddy But I think it's important to discuss that because I think you're right in terms of the ryegrass space, it's likely we're going to have to get outside of the ryegrass species to really have any hope in terms of even going partially on the way to combatting...
Al And there'll be a lot of industry people listening and farmers that are listening today that know they get grass grub every year and know that some time in their careers, they've been told that fescues are one of the solutions to more resilience in a grass grub environment. But ryegrass is so easy. So we like to bag them and we like to do all this but you still don't want to change your system enough to move to probably a more resilient species in those systems. So it is a bit of a call out for people to just be aware that we can talk about grass grub as this really difficult problem. But it's not so difficult that I want to make my farm system complicated by using something more resilient. So yeah, I suppose that's a little bit of a call out in that discussion. But more importantly, we're trying to clarify here that there's nothing simple as a solution when it comes to ryegrass.
Juddy Absolutely. And I guess we could pull the discussion sort of together and now think about this from a farm systems point of view and say, let's have a discussion about the difference in endophytes that we've talked about and in how we might use them and different parts of the country and under different grazing or different farm systems. So how do we go in the Upper North Island, for example?
Al Well, for starters, you know, we see AR37 in our portfolio as our premium endophyte. It's the endophyte that gives more resilience to grass in literally every location in the country. However, you know, AR37 is not perfect in its own right, and therefore there's still a place for AR1 in finishing systems with stock that are susceptible to stagger risk profiles or high-value stock in that space. However, as you look across the country, wherever you have black beetle and light friable soils, AR1 is quite a risk profile because black beetle adults can eat AR1 and lay eggs with an AR1 pasture. On heavy soils, you can almost get away from it, but on lighter soils of the Waikato and parts of Northland, African black beetle really limits the use of AR1 in those environments. AR37 is a really well-suited endophyte to the north. As you drift south into colder environments where African black beetle is not around as much, then you start to ask the question about your stock classes, your belief in resilience, and you want to put more of the, you know, more of the resilience from having a stronger endophyte? Or do you want to have a lamb finishing pasture where you don't even want to think about may I get staggers one year in five, which is a little bit of the risk profile with an AR37. So AR37 singular risk really is the potential for staggers, relative to the history of ryegrass staggers is in the country, it's very minor and in all my experience to date, the only occasions I've seen staggers be really effective on people's farms is under extreme stress where the pasture is staying green. It is the target pasture to be grazing because it is the most resilient, but because the stress is so high all the white clover has disappeared from the pasture. And by the time we get to have the discussion around a stagger event, you tend to find it's mostly a pure stand, never sown as a pure stand, but because of the stresses of the environment, have ended up a pure stand. So we don't tend to see staggers in AR37 ever occur when you're in a diverse mixture, be it with chicory, plantain, cocksfoot and the clovers. However, as I've just described, many of the clovers get stripped out during stress and so if you're in a hot, dry environment like the Wairarapa in a drought time, Hawke's Bay, North Canterbury quite regularly by the time you get to the point where you may one day see a singular paddock create a problem, you may find that there's literally nothing growing in that paddock apart from the ryegrass, and it is the greenest paddock on your farm. Therefore, you're putting the animals on the most successful paddock on your farm, and that's where the risk profile can be. But all in all, in that same situation, AR1 may just die. Because you'll be overgrazing it in the same stressful environment and overgrazing it to such a point that it may not recover. And that's what we found in the early 2000s, when that was first introduced. Soon, as the North Canterbury's of the world got droughts, AR1 pastures resilience came into real question because they were being overgrazed quite intensively.
Juddy So in summer safe, high rainfall areas, you know, parts of Southland. You know, there was a thought previously that there was no need for endophyte...
Juddy Down there...
Al I mean, the standard endophyte created a real problem that was blamed for so many different things and it was quite negative. I mean, you don't have an endophyte that can contribute to an animal outcome called summer ill thrift without not being great. So the move away from endophyte and endophyte is a dirty word really, really rolled out of the 80s and the 90s. So it is a big deal that if you didn't think you needed endophyte, you shouldn't have it, which we killed the endophytes within our seed, which meant that the plants that were growing were growing without the natural relationship with the endophytic fungus, and these were called low endophyte or nil endophyte plants. And there are few parts of the country that can actually tolerate that today, the West Coast of the South Island and definitely some parts of Southland without question still use quite a large amount of low endophyte pasture. However, the risk profile has just been emerging constantly as we all experience these warmer winter conditions, including the South, believe it or not. But the reality is that as releasing pasture pest and pest cycles into areas you weren't expecting. And so, for example, Argentine stem weevil, which devastates low endophyte pasture - destroys it - can be there one minute, literally gone the next, is moving further into different parts of Southland now. Likewise, on the coast, you have pockets of different insects that actually can colonise and do become destructive. So what we were perceived to be safe, with more knowledge we recognise that some of the losses and some of the damage are because we haven't got protection. So AR1 for the south is quite a successful endophyte. And it's a good choice endophyte. But then also in the same climates, you've just described porina as another one of those pasture pests, so therefore you've got the AR37 even in an area that is not the stem weevil that's the primary, but porina could be your target and AR37 is a good endophyte for that.
Juddy So I guess if we were looking at kind of at a high level, the choice of endophyte that you make is really dependent not only on the system that you're driving from an animal point of view, but probably more importantly about the pests that you are going to encounter and the way that they control those in terms of making the, you know..?
Al Absolutely. And that's exactly right. And that's why being aware acknowledging what you're experiencing and listening to people when they say your pasture has just died because of this. Well, what endophytes could I have done that could have made that more resilient? Knowing your farm fit for the style of endophyte, like, for example, a classic statement we would make is you do not put AR37 endophyte behind deer fencing because the risk of staggers with deer is so much more complicated and so much worse. So we do not recommend AR37 for deer and then logically, that's an absolute choice of AR1, which is an animal safe endophyte for that particular stock class. So they are the sort of processes we go through and just because a deer fence, for example, has no deer behind it today, once you plant a perennial pasture, you want to make sure you've really recognised that you're unlikely to see it restocked at a later date and create a problem. So as an industry person or a farmer, you need to think about not just now about what may be going on in the future.
Juddy Excellent. Oh, well, listen, I'm off to check my deer. I got a few out in the back paddock so I might just go and make sure that they are all in the upright position.
Al Well, that's good Juddy but just before you go, I'll just summarise what we have just covered. And basically, you know, when we look at what endophyte means to New Zealand, New Zealand is quite a special place. We've identified that when a lot of insects arrived in New Zealand, they didn't bring their natural predators or parasites that control their populations. So in our temperament environment, most of them have thrived. What that has highlighted is that endophyte has been a very special thing. Once it was discovered for New Zealand pastoral systems, particularly based on ryegrass, we identified this as a living fungus that has evolved with ryegrass to give it advantages in stressful conditions. And we've identified how that passes on through the generations via the seed and that it's a living organism that we must look after for it to be there in the seed in the future and colonise future plants. We've discussed those insects we found in New Zealand to be quite damaging and destructive...
Juddy And I actually found that that was a really good summary of the key pasture pests and how those different endophytes affect those.
Al Yes, and some of them are quite regional. And then we've also just touched on a few of the farm systems and regional spread of what you might consider when you're discussing and looking at endophytes in your pasture. All I can say is that it is an awesome symbiotic relationship and it would be so cool in ag classes around the country if this sort of relationship was discussed because it is very interesting as well. So that would sum up that topic really nicely. That was done at quite a high level, a lot more detail behind all of that, as I assume some of you may have picked up on, but hopefully that gave some interesting insight into what endophytes is in New Zealand ryegrass pastures.
Juddy Thanks Al, see you next time.
Al See you Juddy.