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Miracle moss: add water and watch it grow; moss may have genes to make lawns and crops truly drought-tolerant.

A moss found throughout the United States may hold a gene that will give drought tolerance a new meaning for U.S. crops.

Agricultural Research Service molecular biologist Mel Oliver collects the moss from mountainous U.S. regions. He believes the key to improving economically important crops lies in the vast and relatively untapped gene pools of noncrop plants such as the lowly star moss, Tortula ruralis.

It grows throughout the world but is particularly abundant in North American wilderness areas.

Star moss' quick recovery from drought can be easily demonstrated. As soon as a few drops of water are poured on the dry moss, what once seemed a brown Brillo pad becomes a lush green mass of individual branches with starlike needles.

Viewed through an electron microscope, the dried moss shows massive cell damage. "And yet it somehow repairs most of this damage within minutes," Oliver says.

In the long term, Oliver envisions lawns, rangelands, and pastures that could do the same. "We're talking about using genetic engineering to create a grass that can approach the capability of the star moss to completely dry up, turn brown, and recover quickly when it rains," he says. But Oliver is no mere visionary. It's taken long hours at ARS' Cropping Systems Laboratory in Lubbock, Texas, to put him on the trail of the responsible moss genes.

Oliver reasons that clues to the drought-repair gene begin with those proteins that increase during the recovery period, after the moss has dried out and been remoistened. With two-dimensional electrophoresis--a protein separation technique that uses electrical current and an acrylamide gel--he has found 74 proteins that increase significantly within 2 hours of rewetting.

To find out which genes make these proteins, Oliver extracts RNA genetic material from moss tissue during its critical drought-recovery period. He uses this RNA to make DNA copies of all the genes active during this stage.

RNA and DNA are the biological vehicles for transmitting genetic or hereditary characteristics and for building proteins in plants and animals.

Oliver plans to use the DNA copies as probes to locate the specific star moss genes responsible for its quick drought recovery. But to do this, he must first isolate all the individual moss genes.

Then he will separate each DNA copy of interest into its two exactly matching--complementary--strands and radioactively label one of them. The labeled strands will be put into solutions to interact with separated, fixed, unlabeled strands of the star moss genes. The DNA copies will rewrap themselves around only their exact genetic counterparts. This will mark the locations of the genes responsible for making each of the 74 proteins found so far during the recovery of star moss from drought.

Oliver hopes that only a few gene clusters encode for the proteins involved in the repair process, because that will make it easier to transfer the genes into crops.

"We're one of a few plant laboratories looking at the gene pool of a wild organism," Oliver says. "It shows why it's so important to protect the genetic variation of plants and animals in remote parts of the world. In star moss alone, we might find genes that could make crops truly drought-tolerant, allowing them to survive severe desert-type drought and not just the mild moisture shortages crops are currently bred to survive."

Oliver is pleased that what was once an academic interest to him while teaching at the University of Calgary in Alberta, Canada, may now change forever the meaning of crop drought tolerance.--By Don Comis, ARS.

Mel Oliver is in the USDA-ARS Plant Stress and Water Conservation Research Unit, P.O. Box 215, Lubbock, TX 79401. Phone (806) 746-5353.
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Title Annotation:research by Mel Oliver
Author:Comis, Don
Publication:Agricultural Research
Date:Jun 1, 1992
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