Monday, December 16, 2013

Travel Story: In Pursuit of the Bush Morning Glory

Ipomoea leptophylla
bush morning glory Ipomoea leptophylla
One reason I became a plant ecologist was that my ecology class professor at University of Michigan, Dr. William Benninghoff, left, as planned, in mid-semester. He did research in the arctic and seasons in the tundra don’t wait for anyone. Ah, I observed, ecologists travel!

I had a chance to experience that again this summer.

From Indiana University came Ph. D. student Wesley Beaulieu and Professor Keith Clay to collect morning glory seeds. Not just any morning glory but the bush morning glory Ipomoea leptophylla. Since I had studied the bush morning glory, I agreed to be the local guide.

morning glories
morning glories
The background is this: We have known for decades that morning glories, grasses and sedges are the only vascular plants with ergoline alkaloids. Ergoline alkaloids the group of compounds that include LSD (lysergic acid). Most, if not all, ergoline alkaloids cause symptoms from psychotic behavior and hallucinations to severe indigestion to relief of migraines in humans. It seemed logical that ergoline alkaloids evolved in morning glories to deter animals from eating them. Animals, including humans, learn very fast to avoid foods that upset their stomachs. ( LINK about single exposure food avoidance)

BUT in the early 2000s German researchers revealed that the ergoline alkaloids were not in the plant but in a fungus that was in the plant (see references). Keith Clay has been working on fungi living inside plants for many years, repeatedly surprising the scientific community by finding another case. His experiments have shown that it is frequently a mutualism: the plant benefits because the fungus is toxic to animals that would eat it, the fungus benefits because the plant provides it with a protected place to live, water and nutrients. (Example)

Wesley Beaulieu picked up the story for his thesis research. Not all morning glory species have ergoline alkaloids. So there are many questions about this sytstem. Why don't all species have it? When a species does, does every plant harbor fungus? In the same amount? In the same tissues?

Ipomoea pes-caprae
Ipomoea pes-caprae
To answer these questions required seeds collected across a broad area. With all the human rearrangement of the landscape, that can be surprisingly difficult. Previously Wes and Keith surveyed the beach morning glories, Ipomoea pes-caprae (called bayhops by USDA plants). They collected them on beaches from Florida to Texas. The project is in progress: plants need to be grown, chemistry studied, results tabulated and statistics analyzed. 

Good science requires replication. No matter what the results are from I. pes-caprae, with only that study, it is an isolated set of observations and difficult to generalize from. Generalizations—principles—are the goal of science.  

So Wes and Keith looked for a second chance to ask the same questions. The bush morning glory, Ipomoea leptophylla, is native to sandy grasslands from Texas and New Mexico to Montana. It is an ergoline-positive morning glory but from very different areas than I. pes-caprae and not closely related to I. pes-caprae. In these rangelands the plant is growing pretty much as it has for centuries. 

Wes and Keith flew to Denver on August 20, 2013. I met them in Wiggins, CO, an hour east  of Denver on Interstate 76. 

It was a fiercely hot summer day. When we drove through Brush, CO, an hour later, the bank thermometer said 102 (39C).

We didn't care -- we were botanists on the hunt.

gathering seeds from bush morning glory
Wes gathering seeds from a bush morning glory.
Can you spot a second plant?
Where there is sand in eastern Colorado there are often bush morning glories. June and July of 2013 had above average rainfall so the morning glories had flowered heavily. Being morning glories, the flowers open at dawn and close in the heat of the day. So that first afternoon the plants were hard to spot-- green lumps in the grassland.

bush morning glory
bush morning glory plant

We got better at seeing them.

Ipomoea leptophylla pods and seeds
bush morning glory pods and seeds

                          The seeds

It is not necessarily easy to gather seeds for a project. It is not just the heat or whatever the climate throws at you. It is also figuring out where to find the plant. Bush morning glories grow in eastern Colorado, but we checked a lot of pastures where they did not occur. You also have to go at the right time.  A week earlier most of the seeds would not have been mature (brown, ripe). A week or two later the seeds would have all fallen off the plant.

Furthermore, there is a bruchid beetle that lays eggs in bush morning glory flowers and its larvae consume the seeds from the inside. Sometimes 10 of 10 seeds have a beetle developing inside. (The bruchid is Megacerus discoidus, a rather pretty beetle, actually link). So you collect an insect, when what you wanted a live plant seed. 

But Wes and Keith perservered, collecting extra seeds in order to be sure they got some without beetles. 

And we were all buoyed by new observations. For example, Wes discovered that you can see the fungus on the leaf surface. I had observed in 1980s that cattle don’t eat bush morning glory leaves if they can avoid it. No wonder! if there are so many fungal cells that the leaves are grayish. Wes and Keith started collecting 2 or 3 leaves from each plant sampled to compare leaf fungi as well as seed fungi. 

Moon rise over the prairie
Moon rise over the prairie
It took darkness to end our collecting day.
Wes Beaulieu and Keith Clay
Wes Beaulieu and Keith Clay 
Indiana University
successful bush morning glory hunters

I sent them off northward across western Nebraska, having done my job as local guide.

What fun! The Colorado and Nebraska bush morning glories, just weeds along the road most of the time and to most people, are now contributing to better understanding of the distribution of fungi and plants, of fungi in plants, and complex relations between very different organisms. 

Ipomoea leptophylla pod and seeds
Ipomoea leptophylla
pod and seeds

One final note:  For me, this is a clear, specific example that what we know changes in biology. In ways we would never predict. I personally studied the bush morning glory for about a decade and in doing so thought a lot about where it lives and how it grows. I knew about the ergoline alkaloids in it, but that it is really a fungus that has the alkaloids--that was totally unexpected. It makes me rethink my ideas about the plant. And so the scientific understanding of nature evolves.

Comments and corrections welcome.

Relevant References

Ahimsa-Müller, M.A., A. Markert, S. Hellwig, V. Knoop, U. Steiner, C. Drewke and E. Leisner. 2007. Clavicipitaceous fungi associated with ergoline alkaloid-containing Convolvulaceae. Journal of Natural Products. 70: 1955-1960.
Beaulieu, W. T., D. G. Panaccione, C. S. Hazekamp, M.C. McKee, K. L. Ryan and K. Clay. 2019. Differential allocation of seed-borne ergot alkaloids during early ontogeny of morning glories (Convolvulaceae). Journal of Chemical Ecology 39:919-930.
Clay, K. and G.P. Cheplick. 1989. Effect of ergot alkaloids from fungal endophyte-infected grasses on fall army worm (Spodoptera frugiperda). Journal of Chemical Ecology. 14: 169-182.
Clay, K., J. Holah and JA Rudgers. 2005. Herbivores cause a rapid increase in hereditary symbiosis and alter plant community composition. American Naturalist. 160:S99-S127.
Clay, K, S. Marks, and G. P. Cheplick 1993. Effects of insect herbivory and fungal endophyte infection on competitive interactions among grasses. Ecology 74:1767–1777.
Kucht, S., J. Gross, Y. Hussein, T. Grothe, U. Keller, S. Basar, WA König, U. Steiner and E. Leistner. 2004. Elimination of ergoline alkaloids following treatment of Ipomoea asarifolia (Convolvulaceae) with fungicides. Planta. 219: 619-625.

 Kathy Keeler, A Wandering Botanist
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  1. How did you know where to look? Do Ecologists in Plant Sciences have reference maps of what soils/what plants?

  2. Yes, but they are rarely detailed enough. That's why I was the local guide. I made it much easier to recognize the plant and know where to look. (Bush morning glory leaves remind me of French-cut green beans in color and shape, it likes sandy soils, especially on a slope.)

  3. I’m trying to learn all I can about Bush morning glory. I am a retired horticulture professional with botany background. I now live in the Sandhill region of Nebraska. So far, I only know of two plants, about 25 miles separated. Question is why so few and how genetically related if this disparate. Ideas? References to read? Thank so much.