"Mycorrhizal Symbioses in Forests: What do DNA and Fungal Isolation tell us?" by Dr. A. Kevin G. DJOTAN

Abstract:

Arbuscular mycorrhizal fungi (AMF) simultaneously inhabit the soil and the roots of their host plants, enhancing plant nutrient uptake in exchange for photosynthetically derived carbohydrates. Because of this mutualism, AMF represent promising bioinoculants for cultivating healthy plants in healthy soils. Despite their importance, the diversity and ecology of AMF in forest ecosystems remain largely understudied. To address this gap, a pilot study was first conducted to establish a reliable method for assessing AMF communities in both the roots and surrounding soil of specific host tree species. This approach was then applied in an intensive, long-term investigation of AMF diversity and ecology in forests, using Cryptomeria japonica and Chamaecyparis obtusa (Cupressaceae)—the two most widely planted tree species in Japan—as hosts.

Prior to this work, their primary AMF symbionts were poorly understood. The study recovered 2,155 operational taxonomic units (OTUs)—a molecular unit used to estimate microbial diversity—from root and soil samples. In the roots alone, 134 major OTUs (≥1% relative abundance) and 34 dominant OTUs (≥10% relative abundance) were identified, belonging to Dominikia, Glomus, Microkamienskia, Rhizophagus, Sclerocystis, and several unidentified AMF taxa. Overall, the data showed taxon-specific patterns of root and soil exploration, suggested possible intra-radical competition or complementarity among AMF, revealed seasonal and spatial shifts between root and soil communities, and indicated microhabitat-driven transitions of AMF to neighboring herbaceous plants.

In the upcoming seminar, I will first discuss these molecular findings with an emphasis on contrasts between DNA-based data and bioresources availability. I will then present several current research directions, including the isolation and characterization of unknown AMF “dark taxa” and their associated bacteria in forest ecosystems, the relationship between AMF cohabitation and functions, and the first discoveries and cultures of bacteria inhabiting AMF spores (AMF endospore bacteria). The seminar will conclude with a discussion on the need to establish AMF bioresources and to explore dark AMF taxa, highlighting how such efforts can support a wide range of applications.

Biography:

Kevin, who will soon join the Microbial and Ecosystem Ecology Unit, is a JSPS postdoctoral researcher currently based at Mie University in Japan. His work centers on developing living culture collections of arbuscular mycorrhizal fungi (AMF) and advancing understanding of their biology, diversity, ecology, functions, and taxonomy. He earned his Ph.D. and M.Sc. in forest sciences at the University of Tokyo, specializing in mycology and mycorrhizal symbiosis, following professional Bachelor’s and Master’s degrees in forestry and forest management from the University of Abomey-Calavi. In addition to his academic training, he has gained expertise in biodiversity informatics, ecological niche modeling, programming for data processing, geographic information systems, and mapping. Outside of research, Kevin enjoys photography, international development, and intercultural exchange.

Zoom Link: https://oist.zoom.us/j/98313690426?pwd=I1BT177QSPFD3CI81bkcY7XgEQIJCm.1
Meeting ID: 983 1369 0426
Passcode: 771130