Stress Monitoring in Plants via Chlorophyll Fluorescence...

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Stress Monitoring in Plants via Chlorophyll Fluorescence and Plant Pigment AnalysisMTV Workshop, 202011 March 2020, 11:05 am

L. A. Finney, P. J. Skrodzki, M. Burger, J. Nees, and I. JovanovicDepartment of Nuclear Engineering and Radiological Sciences, University of Michigan, 48109

Gerard Mourou Center for Ultrafast Optical Sciences, University of Michigan, 48109

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Team members and collaborators

MTV TeamUniversity of Michigan

L. A. Finney P. J. Skrodzki Dr. M. Burger Prof. I. Jovanovic

J. Nees

Van Vlack Laboratory for Instrumentation

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Mission relevance: remote, rapid detection of nonproliferation-relevant materials

Laser-based methods excite characteristic emissions that enable rapid, remote characterization of the makeup of any target.

Airborne laser scanning over extended distances may be used to track emissions and environmental contamination in order to detect undeclared nuclear activities such as uranium enrichment.

EPFL

S. Kemp, Sci. Glob. Sec. 16, 115 (2008)

DOE

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One potential method to monitor enrichmentactivities is through plants’ optical properties

Chlorophyll fluorescence imaging has been used extensively for large scale monitoring of CO2 uptake and circulation for climate change assessment.

We want to use laser excitation to understand plants’ response to other stresses, such as exposure to uranium in environments where solar-induced fluorescence is weak.

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The objective is to characterize spectral changesin response to stress for remote monitoring

Absorption spectroscopy Ultrafast fluorescence spectroscopy

detectorpigmentsamplelight

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We exposed pachira aquatica (Money Tree)to three different environmental conditions

Control2x 150 mL Dis. H2O

No water Pb(NO3)2(aq) 1000 ppm 2x 150 mL

Control 1 Control 2Heavy metal contaminant

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Plant pigments can be extracted using polar solvents1) Boil leaf to open pores

2) Move leaf to 50 mL of isopropanol and add beaker to hot water bath

3) Let sit for ~30 min, until pigments are extracted

4) Transfer solution to cuvette for analysis

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The absorption spectrum consists of several different pigments that contribute to plant health

Lichtenthaler, Methods in Enzymology: Chlorophylls and Carotenoids, 148, p. 350-382(1987).

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Absorption spectroscopy provides information on how pigments change under stress

detector(%T à A)

pigmentsamplelight

Healthy - pre-stress

Days after 2nd exposureexposure condition 1 2

Chl a:Chl b Chl:Car Chl a:Chl b Chl:CarControl 1 (watered) 7.23 3.14 2.68 4.93

Control 2 (unwatered) 3.16 5.22 3.42 4.87

Pb watered 5.08 2.93 3.29 4.31

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We use ultrafast laser excitation for time-resolved fluorescence decay measurements

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Time evolution of both peaks can reveal information about the response to different stresses

T675:T720Pre-stress 1.3

Day after 2nd exposureexposure condition 1 2

T675:T720 T675:T720control (watered) 1.0 1.0

control (unwatered) 0.9 1.1Pb watered 1.3 1.0

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Absorption and fluorescence are promising for measuring the plant responses to different environments

Control 1 Control 2Heavy metal contaminant

More samples per day per exposure and systematic study are needed for confirmation.

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Future work: systematic study including uranium stress

Uranyl nitrate (UO2(NO3)2) salt sample from UNLV – will be used for uranium exposure in soil of plants

Drought Control(watered)

Leadcontaminated

Uraniumcontaminated

We are currently growing spinach (spinacia oleracea) for a systematic study to distinguish uranium exposure from other stresses.

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Impact: Development of remote, in-situ environmental monitoring for identification of nuclear nonproliferation relevant materials

J. Walsworth, U.S. Plant took subaru on new journey, web (2018).

https://www.thinplytechnology.com/markets/uav-drones

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MTV impact: National lab collaborations and internships

Collaboration:Dr. D. Weisz

Through CVT I did an internship at LLNL last summer as a Seaborg Institute summer intern.

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The Consortium for Monitoring, Technology, and Verification would like to thank the NNSA and DOE for the continued support of these research activities.

This work was funded by the Consortium for Monitoring, Technology, and Verification under Department of Energy National Nuclear Security Administration award number DE-NA0003920

Acknowledgements

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Backup slides

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Decay constant provide information about quenching and efficiency of different photosystems in the plant

Baker, Annu. Rev. Plant Biol., 113, 89(2008).

Buschmann, Photosyn. Res., 92, 261(2007).

PSII reaction center called P680 (primarily fluoresces at 680 nm)PSI reaction center called P735 (primarily fluoresces at 735 nm)

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Pigment ratios

Days after exposureexposure condition 1 2

ChlA:ChlB Chl:Car ChlA:ChlB Chl:CarControl

(watered) 7.23±0.18 3.14±0.01 2.68±0.13 4.93±0.15

Control (unwatered) 3.16±0.05 5.22±0.02 3.42±0.06 4.87±0.03

Pb watered 5.08±0.15 2.93±0.02 3.29±0.10 4.31±0.07

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Time decay constants

T675:T720 errorPre-stress 1.3 0.4

Day after exposureexposure condition 1 2

T675:T720 error T675:T720 errorcontrol (watered) 1.0 0.2 1.0 0.1

control (unwatered) 0.9 0.4 1.1 0.1

Pb watered 1.3 0.6 1.0 0.1

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Absorption spectra recordedfor the 3 plant environments

Control 1 (watered)

Control 2 (unwatered)

Pb(NO3)2(aq) 1000 ppm 2 x 150 mL

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