[Enviro-lunch] Spring 2022 Enviro-lunch starting next Monday (1/31)

[Kyungjin Min]

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Welcome back all,



The first seminar by Mariela Garcia Arrendondo at the University of
Massachusetts-Amherst will be presented next Monday (1/31).  Please
join us between 12-1 pm (pacific) via zoom.



https://ucmerced.zoom.us/j/175736103



Title: A Glimpse Underground: Sensing Functionally Distinct Microsites
within the Rhizosphere

Abstract: Understanding the dynamics and vulnerability of mineral-organic
interactions is critical for projecting climate change impacts on soil
fertility and carbon storage. Plant roots and associated microbes release
an array of reactive rhizodeposits, potentially both forming and disrupting
protective mineral-organic associations (MOAs) in the surrounding soil. But
our ability to measure and predict the impact of rhizodeposits on the
dynamics of MOAs in the rhizosphere remains limited. Here, we combined an
innovative use of a diverse series of micro(bio)sensors into a succession
of experiments to assess the fate of MOAs within dynamic, biogeochemically
distinct microenvironments in the rhizosphere. We then combined this
in-situ micro(bio)sensors approach with mass spectrometry to follow the
impact of single roots on the dynamics of protective iron (Fe)-organic
matter associations.

Continuous, high-resolution monitoring of growing and maturing Avena sativa
roots from collection of microdialysis, micro-electrode, and
micro(bio)sensor measurements revealed dramatic changes along transects,
from root tip to uptake zone, and mature suberized zones. Root tips showed
a sharp decline in pH and redox potential as well as a concurrent increase
in microbial activity, Fe and DOC concentrations. As roots matured,
microbial activity decreased while pH and redox potential recovered
followed by a decline in Fe and DOC concentrations. Metabolite analysis via
tandem mass spectrometry (LC-FT-ICR-MS) shows a progression of functionally
distinct rhizodeposits such as organic acids, amino acids, and lipids from
root tips to more mature zones. These changes in microenvironment
conditions along the root axis hold the potential for disrupting protective
Fe-organic matter associations.

Our results suggest that the fate of MOAs in the rhizosphere depends, in
part, on the distinct nature of transient microenvironments emerging around
different root segments. Our micro(bio)sensor approach provides the unique
ability to systematically assess the dynamic interplay between roots,
microbes, and minerals within these microenvironments. Future development
and application of this combination of micro(bio)sensors can further
provide us with insight into the role of roots in soil carbon storage and
nutrient acquisition.
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Bio: Mariela is originally from Fort Worth, TX and joined the Keiluweit lab
in Fall of 2016 after finishing her undergrad at Cornell University. Her BS
was in Science of Earth Systems, which she concluded with an honors thesis
in soil organic matter regeneration on desertified grassland soils. She was
awarded a Spaulding-Smith Fellowship and a National Science Foundation
Graduate Research Program fellowship for her research at UMass Amherst
aimed to further our understanding of the mechanisms induced at the
rhizosphere between soil minerals and plant roots and their associated
microbes. Specifically, how rhizosphere processes can drive mineral-organic
association vulnerability in soils and their potential for carbon storage.
Mariela also co-founded an initiative during her time at UMass, BRiDGE,
which aims to increase the representation and visibility of early career
scientists from underrepresented groups in departmental seminars to help
combat attrition of underrepresented graduate students. She has worked on
the Board of Advisors at the Eagle Eye Institute in Holyoke, MA where her
outreach focuses on connecting middle school students with soils while
taking them on soil hikes to learn about soil health and the local food
systems. Mariela firmly believes that none of our environmental solutions
will be effective if we continue to lack the voices of those most affected
by a changing climate. In the future, she would like to work as a soil
scientist either advising policy or developing projects focused on bridging
the gap between environmental research in soil biogeochemistry and its
application (e.g., sustainable land development, remediation). During her
free time, she enjoys cooking, gardening, and painting.


Sincerely,

co-host: KJ Min & Manisha Dolui

faculty coordinator: Asmeret Asefaw Berhe


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Spring 2022 Enviro-lunch schedule
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