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The III International Symposium on Mycorrhizal symbiosis
South America
24th – 30th August 2023
My PhD project is based around investigating the interactions of mycorrhizal fungi with soft fruit, with a focus on their impacts on plant pathogens, especially Phytophthora spp. I am very grateful for the BSPP in funding this opportunity for me to meet and learn from such a range of mycorrhiza experts and researchers.
This conference was in a fantastic location; the event was split between two sites operated by different organisations, SINCHI and Universidad Nacional de Colombia, both of which run research groups in the Colombian town of Leticia, on the shores of the Amazon River, surrounded by rainforest. Leticia connects with the Brazilian town of Tabatinga, with neither town connected to the rest of the country by road; the river also marks the Peruvian border. All three currencies are freely used in the area, making expenses tricky to calculate!
The conference included an optional practical/theory course from Thursday to Saturday, starting with a collecting trip into two different forest types. The first area was white sand forest, a low fertility area with widely spaced short shrubby trees, easily accessed from the road, while the second area, regularly inundated, was more like the traditional image of the Amazon rainforest with tall trees and dense vegetation. This second site was over three hours trek away, with no trails for almost the last hour. The primary goal of this trip was to collect roots and soil from two distinct morphotypes of an indigenous tree to characterise their root endophytes. Taking samples was tricky, as the roots formed a dense mat covering the soil and it was very hard to identify which root was from which tree. We also collected roots from other unidentified trees nearby – a botanist accompanied the group, but identifying such tall trees when all the leaves are high in the canopy, especially in such a diverse area, is not a simple task. The trees sampled from were marked so they could be relocated later, in case the trees could not be identified from the samples. Very different from the field sites I’ve sampled from before!
Despite the temperature reaching over 35°C, high humidity, and the unwanted attention of a species of large, sneaky, and very persistent biting fly, the trip was an amazing experience, especially as we were accompanied by a group of local ecological experts happy to answer questions. We were all too exhausted when we got back to Leticia to even get the ice creams we’d been longing for all day.
The next two days were in the lab, sorting the samples we’d collected and learning imaging and identification techniques. The first day was dedicated to ectomycorrhizal fungi; how to select the most likely candidates and prepare slides. Almost all of this was new to me, as my main focus is on endomycorrhizas, which we looked at on day 2, clearing and staining the roots. We found some great samples, including one sample with both endo and ecto mycorrhizas visible in the same segment, something which is not supposed to happen!
After a Sunday break, the conference started on Monday morning. As a way of lowering the barrier to entry for early career researchers, while slides were all presented in English, talks were given in a choice of English, Spanish or Portuguese. While this did mean that some talks were difficult for me to understand with my limited Spanish, it also meant a lot of people – especially students – were able to attend and present who would otherwise not have been able to. A common theme during the conference was increasing access to the research community for those from less wealthy areas and backgrounds and how this gap in access leads to gaps in research.
Discussing my poster at the conferenceMost attendees were based in South America, with some from Europe or North America and a few from elsewhere. The talks were very varied, including some thought-provoking local data presented by Clara Peña Venegas, based at SINCHI, demonstrating how prediction models and generalisations from temperate regions do not always apply to the tropics. A few other researchers were also looking at mycorrhiza-pathogen interactions, which was especially interesting to me due to the relevance to my project.
One of the more interesting talks for me was by Bala Chaudhary on developing a framework for AMF (arbuscular mycorrhizal fungi) spore functional traits, with the goal of creating a prediction model for fungus traits; one of the major issues in using mycorrhizas in the field currently is their variability and unpredictability. This issue was highlighted by several presenters from a team led by Ian Sanders, who also gave a talk remotely, reporting on a large project investigating AMF impacts on cassava. Spores produced by asexual reproduction in AMF can vary considerably in their effects; this is hypothesised to be due to the multinucleate nature of the fungi resulting in different nucleus populations in different spores. In the cassava study, different single spore offspring of the same AMF parent had impacts on crop yield varying from none to an increase of 180%, with the effects being repeated in multiple years in the same site, apparently independent of phosphate addition. However, which isolates caused increases differed between sites, with these impacts not currently predictable.
Attending this event was an amazing opportunity, and a fantastic experience, especially as a first year PhD student attending my first research conference!
Hazel Marsden
The James Hutton Institute and the University of Warwick
TOP IMAGE: The typical inundated forest floor; easy to find roots, hard to trace them
