Cooperative plants

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(HOST) If the earth is going to continue warming, commentator Ruth Page thinks that a recent discovery concerning a complex form of plant cooperation may turn out to have great value.

(PAGE) Put grass into soil heated to 149 degrees Fahrenheit, and it shrivels and dies. We can hardly blame it; 149 is really HOT. But a group of ecologists in Ardmore, Oklahoma, were surprised to discover at least one species of grass thriving at that temperature. They did some experiments to discover “how come.”

The question led them to a discovery unique in the annals of plant science so far, though they now suspect and hope – it may turn out to be fairly common.

The grass, with the fancy name Dichanthelium lanuginosum, accepts extreme heat because of a fungus that lives within it as a symbiont. (Symbiosis is a sort of buddyship between two living plants that live together, each giving something, and getting something, from the other, to promote the health of both).

Ecologists thought this symbiosis fully explained the success of the grass in hot temperatures. Experiments showed they were mistaken. When the grass and fungus grow separately, each can survive only to a hundred degrees; together they make it to a feverish 149. But they found out this only works when the fungus has a virus infecting it.

When experimenters inoculated the grass with a fungus that lacked the virus, both died in 149-degree soil. When they inoculated the fungus with the virus, the three had a successful partnership and they all throve. It was the need for THREE cooperators that appeared to be unusual.

Further work, possibly of interest to gardeners, showed the fungus with the virus was just as protective to tomato plants on which it was tested. Of course tomatoes and grass are quite distant relatives, so that led to a further suspicion. Maybe, ecologists figured, the virus affects some internal mechanism for heat tolerance that is common to many different plants.If they are right, this may be a vital piece of new information. Many climate specialists believe earth-warming is destined to continue for something like forty years even if we take steps immediately to control it (which so far the world has barely begun to do).

That could mean the better part of a human lifetime will be lived in a rapidly-warming climate. So we may be grateful to a virus-plant-fungus cooperative group.

There are many questions still to be asked. If the combo is helpful to a wide variety of food and other plants, might it possibly lead to one more way of coping with what could be a serious change in our planet’s climate?

Ruth Page has been following environmental issues for twenty years. She is a long time Vermont resident and currently lives in Shelburne.

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