Poplar as a model for dissecting early mycorrhizal signaling in woody perennials
K. COPE (1), M. Venkateshwaran (2), J. Maeda (3), C. Ma (4), S. Strauss (4), J. Ané (3) (1) University of Wisconsin–Madison, U.S.A.; (2) University of Wisconsin-Platteville, U.S.A.; (3) University of Wisconsin-Madison, U.S.A.; (4) Oregon State University, U.S.A.

Two ecologically and economically important mycorrhizal symbioses are arbuscular mycorrhizae (AM) and ectomycorrhizae (ECM). Significant advances have been made in elucidating the molecular mechanisms controlling mutual recognition between AM fungi and their host plants. In contrast, our understanding of these mechanisms in ECM associations is still limited. In AM associations, the fungus releases various signaling molecules that are recognized by the host plant, including lipo-chito-oligosaccharides (LCOs) and chito-oligosaccharides (COs). We hypothesized that similar signaling molecules are released by ECM fungi and that they too are perceived by plant roots leading to changes in root architecture and gene expression. We performed root hair deformation assays with Medicago truncatula and Vicia sativa to test for the presence of LCOs in the exudates of several ECM fungi. For all ECM fungal species tested, root hair deformations occurred similar to those induced by purified LCOs. We therefore tested the ability of various types of LCOs to regulate lateral root formation in hybrid poplar (Populus tremula x alba). Non-sulfated LCOs induced significantly more lateral roots per length of primary root compared to sulfated LCOs and the negative control. We therefore performed an RNA sequencing experiment on poplar roots treated with isolated fungal signals (LCOs and COs) as well as multiple ECM fungal exudates to identify similar transcriptomic responses. Some similarities existed between treatments thus suggesting a potential role for LCOs as signaling molecules in ECM associations.

Abstract Number: P2-19
Session Type: Poster