Mutation Turns Friend to Foe

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Mutation turns friend to foe, as described in ScienceNOW 29 Mar 2006. Many plants and fungi share a symbiotic relationship that enhances the life of both, but some fungi are very destructive of plants. A group of scientists led by Barry Scott, a plant ecologist at Massey University in Palmerston North New Zealand studied a fungus named Epichloe that lives in ryegrass plants. As the ryegrass leaves grow the fungus sends out strands called hyphae which live between the cells in the leaves. When the leaves stop growing the hyphae stop growing and the fungus helps the plant acquire more nutrients so it can grow more vigorously and survive dry spells. If the fungus continues to grow after the leaves stop growing it stunts the growth of the plant and will eventually kill it.

Scott’s team made 220 mutant Epichloe fungi and found one that had hyphae that grew unchecked. The mutation in this fungus had knocked out a gene whose function was to produce molecules called free radicals. In the normal grass-fungus relationship the plant stimulated the fungus to produce free radicals when the leaves stopped growing. The free radicals inhibit the growth of the hyphae, thus keeping the plant and fungus growth even. Without them the mutant fungus kept on growing and damaged the plant.

Free radicals are normally considered to be dangerous to living cells, but this case shows they can be put to good use if kept under control. Christopher Schardi, a plant physiologist at University of Kentucky commented that there are probably many genes involved in keeping plants and fungi in a right relationship and this study gives some suggestions for further research in plant-fungi associations.

Editorial Comment: Many fungi have been found to enhance plant growth and it seems that just about all plants have a symbiotic relationship with fungi. It was only after the fungus had a gene damaged, i.e. lost some useful information, that it started harming the plant, because it was unable to respond to the growth limiting signals from the plant. Creation Research predicts that gene studies of other disease causing fungi will reveal that the disease process is due to mutation in the genes regulating growth, just like this case, and fungal diseases will provide good evidence that the world has gone from created perfection to degeneration, just as the Bible describes. (Ref. pathogenesis, mycology, parasitism, prediction)

Evidence News 12 April 2006