Researchers at Michigan Tech are transferring altered genes into fungi that facilitate the flow of nutrients through tree roots to help trees protect themselves against disease and insects.

Using "doctored" genes to impart desired characteristics into fungi that live symbiotically with tree roots can ultimately help trees grow faster and live healthier lives, according to Project Leader Dr. Gopi Podila, a molecular biologist in Michigan Tech's Department of Biological Sciences.

"Ectomycorrhizal (on top of the root) fungi provide a major network in the soil for making nutrients available to tree root systems," explains Podila. " By breaking down minerals locked up by acidic soils caused by the decomposition of needles, leaves, and other forest litter, fungi facilitate the passage of those nutrients from the soil to the tree. The fungus, in turn, draws food from the tree, enhancing its own survival. Another benefit of this symbiotic relationship is that the fungus can grow wider and deeper into the soil--and this greatly increases the outreach of the tree in its search for essential minerals."

Podila says that normally when you try to put a fungus on a plant, the two try to kill one another, but fortunately this mutually beneficial relationship has evolved in nature over the course of millions of years. "One of the things we want to determine," he says, "is how they communicate with one another--how do they each let the other know that they are friendly." He says the process is a long one.

"It's almost like a courtship. The fungus gradually approaches the tree root system and this can take as long as three or four months. And even then, the fungus is 'turned on' only to specific host signals. The fungus prepares itself to form the association with the host plant by expressing specific symbiosis-related genes. These genes are turned on by the right plant signals, and this process is controlled by DNA sequences called 'promoters.' These promot
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Contact: Dr. Gopi Podila
gkpodila@mtu.edu
906-487-3068
Michigan Technological University
23-Apr-2000