Abstract Detail

Symbioses: Plant, Animal, and Microbe Interactions

Arnold, A. Elizabeth [1], Gallery, Rachel [2], Baltrus, David [1].

Endohyphal bacteria modulate saprotrophy by endophytic fungi in vitro and under field conditions.

Endohyphal bacteria (EHB) are increasingly recognized for modulating the phenotypes of plant-symbiotic fungi under diverse conditions. We examined the influence of facultative EHB on plant tissue degradation and substrate use by fungal strains isolated as foliar endophytes with saprotrophic life phases, with a special focus on the production of plant cell wall degrading enzymes. We first produced strains of the focal fungi with and without EHB. We then assayed the activity of these EHB+ and EHB- clones in parallel. In vitro assays demonstrated that EHB increased cellulase and ligninase activity relative to fungi without bacterial symbionts. In some cases EHB enhanced fungal growth on media with only cellulose or indulin as nutrient sources. Strains with EHB consistently grew more rapidly on dried leaf tissue than strains without EHB, and fungal growth was consistent with mass loss from plant tissue over time. Biolog characterization revealed that EHB altered the breadth and efficiency of use of diverse carbon substrates. Finally, a field litter experiment revealed that observations of mass loss, enzyme activity, and tissue degradation observed in vitro scaled readily to natural environments, but in a context-dependent manner. These results highlight the capacity of EHB to modulate ecological modes of plant-associated fungi, with potential implications for evolutionary dynamics of major clades of plant-symbiotic and saprotrophic fungi.

1 - University of Arizona, School of Plant Sciences, Tucson, AZ, 85721, USA
2 - University of Arizona, School of Natural Resources and the Environment, Tucson, AZ, 85721, USA

none specified

Presentation Type: Oral Paper
Number: 0004
Abstract ID:1067
Candidate for Awards:None

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