|Redman, R - U.S. GEOLOGICAL SOCIETY|
|Roossinck, M - NOBLE FOUNDATION|
|Maher, S - NOBLE FOUNDATION|
|Andrews, Q - NOBLE FOUNDATION|
|Rodriguez, R - U.S. GEOLOGICAL SOCIETY|
Submitted to: Symbiosis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 15, 2002
Publication Date: May 2, 2002
Interpretive Summary: A non-pathogenic mutant of a pathogenic fungus (Colletotrichum magna) was inoculated into watermelons and tomatos for a field study. This mutant (Path-1) had been previously shown to enhance growth and drought tolerance in laboratory conditions. To test the effect in the field mutant inoculated plants were compared to control, uninfected plants for growth and yield throughout a complete growing season in Oklahoma field plots. The Path-1 infected plants produced greater watermelon yields, improved tomato growth and was not transmitted to uncolonized plants. These results indicate that there is no metabolic costs associated with the symbiosis and that the symbiosis is maintained in the field conditions.
Technical Abstract: Path-1 is a UV-induced non-pathogenic mutant of a virulent Colletotrichum magna isolate that establishes mutualistic symbioses with cucurbit and tomato species. Under laboratory conditions, this mutualism results in plant growth enhancement, drought tolerance, and disease protection against fungal pathogens. This study focuses on the efficacy of this symbiosis and the symbiotic lifestyle expressed by path-1 in the absence of disease stress. The effects of colonization by path-1 on fruit yields and growth was measured in filed plots with four cucurbit species including four watermelon cultivars, and two tomato cultivars, over four growing seasons. The persistence of the symbiosis, extent of colonization and path-1 transmission were also assessed. Yields from path-1 infected plants were equivalent to or greater than yields from non-inoculated control plants and path-1 systemically colonized plants throughout each growing season. Path-1 also increased the growth rates of tomato plants and was not transmitted to uncolonized plants. The results indicate that there are no metabolic costs of this symbiosis and the symbiosis is maintained under field conditions.