PARENT SESSION
Poster Session #25: Mycorrhizal Fungi and Root Processes.
Tuesday, August 6. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC
98
Arbuscular mycorrhizal fungi affect fecundity of Mimulus guttatus when grown across a pH gradient.
Bunn, Rebecca1, McCauley, Ann*,1, Zabinski, Catherine1, 1 Montana State University, Bozeman, MT
ABSTRACT- The soils adjacent to thermal areas in Yellowstone National Park are characterized by sparse vegetation, a wide pH range, and rooting zone temperatures up to 57oC. Our research has shown that arbuscular mycorrhizae (AM) are present in these thermal soils, and that mycorrhizae increase plant fitness in soils with elevated temperature (40oC). The goal of this study was to evaluate the effectiveness of mycorrhizae in acidic, neutral, and alkaline environments in the greenhouse. The experimental objectives were: 1) to asses the effect of mycorrhizal relations on the fitness of Mimulus guttatus (yellow monkey flower) in soils amended with acidic (pH 3.5), neutral (pH 6.5) and alkaline (pH 9.5) solutions; and 2) to determine whether the source of the fungal community affects this relationship. Mycorrhizal treatments included a control, and addition of inoculum from one of 3 sources: thermal acidic soils, thermal alkaline soils, and non-thermal neutral soils. Plant fitness was measured as days to flowering and total number of flowers. Neither fungal source nor watering solution pH had a significant effect on days to flowering or total number of flowers; however, there was a nearly significant fungal source x pH interaction effect on the total number of flowers at 62 days (p = 0.078). Mimulus guttatus grown with the alkaline fungal community had more flowers at pH 3.5 and 9.5 than at pH 6.5. Conversely, M. guttatus grown with the non-thermal neutral fungal community had more flowers at pH 6.5, than at pH 3.5 or 9.5. These data suggest that AM fungi from more extreme environments are more beneficial to the host plant when grown under extreme conditions, and less beneficial when grown at a neutral pH. The change in function across environmental gradients may indicate that the fungal communities are composed of different species or of different ecotypes.
KEY WORDS: arbuscular mycorrhizal fungi, Mimulus guttatus, Yellowstone, thermal soils