Dr. Laura Junker-Frohn

Previous research
I received my PhD in 2016 from the University of Toronto, Canada, for my studies about photoprotective isoprenoids as indicators for stress responses in forest trees, focusing on intraspecific variation of photosynthesis and photoprotective mechanisms of Douglas-fir under abiotic stress conditions. As part of the DFG-funded DougAdapt project, I related my work on photosynthetic gas exchange, chlorophyll fluorescence and photosynthetic pigments to analyses of transcriptomes, volatile isoprenoid emissions, isotope signatures, wood properties and tree growth. In addition, I developed a side project investigating physiological changes in senescing sugar maple leaves, linking the decay of the photosynthetic apparatus during senescence with changes in the spectral reflectance and color representation in digital images, using photosynthetic pigments as optical indicators.

In 2015, I started my first Postdoc at the Forschungszentrum Jülich GmbH, investigating the bioeconomy potential of residual tomato plant biomass for the extraction of secondary metabolites with industrial relevance in the project InducTomE. In this project, I studied the induction of the secondary metabolism of tomato plants in response to different abiotic stresses, and developed a mobile plant imaging device for the fast and inexpensive phenotyping of plant stress responses.

In the project OG Precision Horticulture (2017-2020), I investigated the effect of aphid infestation on spectral properties of lettuce plants (don't try: there is none). The project aimed to develop a non-invasive method for early detection of aphid infested lettuce plants as prerequisite for the selective spraying of infested lettuce plants. Hoewever, diverse experiments under controlled and field conditions could not reveal local or systemic changes of plants' spectral reflectance.

The project OPTIKO (2020-2022), studied the potential of UAV-based RGB- and multispectral images of cauliflower fields to identify heterogeneities in plant development and predict harvest dates using machine learning algorithms. This project was the first one, which I designed and successfully applied for funding, together with a great consortium. The combination of low-cost UAV-based RGB/ multispectral cameras with novel machine learning algorithms has the potential to contribute to the digitalization of agriculture - data analysis is still ongoing.

Publications PhD Laura Junker-Frohn

Peer-reviewed publications

Lu W, Zeng Y, Vilfan N, Huang J, Van Wittenberghe S, He Y, Gao Y, Junker-Frohn LV,  Su W, Liu Q, Siegmann B, Hao D: Characterizing leaf-scale fluorescence emission with spectral invariants. (Accepted with minor revisions by Remote Sensing of Environment)

Quiros-Vargas J, Siegmann B, Bendig J, Junker-Frohn LV, Jedmowski C, Herrera D, Rascher U: Remote sensing of solar induced chlorophyll fluorescence (2024). In T. Prassad (Ed.), Remote Sensing Handbook (2nd ed., Vol. III). CRC Press

Jollet D, Junker-Frohn LV, Meyer-Lüpken T, Steier A, Müller-Linow M (2023): A new computer vision workflow to assess yield quality traits in bush bean (Phaseolus vulgaris). Smart Agricultural Technology 5: 100306

Kierdorf J, Junker-Frohn LV, Delaney M, Donoso Olave M, Burkart A, Jaenicke H, Muller O, Rascher U, Roscher R: GrowliFlower (2022): An image time series dataset for GROWth analysis of cauLIFLOWER. Journal of Field Robotics 40 173–192

Reimer JJ, Thiele B, Biermann RT, Junker-Frohn LV, Wiese-Klinkenberg A, Usadel B, Wormit A (2021): Tomato leaves under stress: a comparison of stress response to mild abiotic stress between a cultivated and a wild tomato species. Plant Molecular Biology 107: 177–206

Ruett M, Junker-Frohn LV, Siegmann B, Ellenberger J, Jaenicke H, Whitney C, Luedeling E, Tiede-Arlt P, Rascher U (2021): Hyperspectral imaging for high-throughput vitality monitoring in ornamental plant production. Scientia horticulturae 291: 1105461 (data available on figshare)

Drees L, Junker-Frohn LV, Kierdorf J, Roscher R (2021): Temporal prediction and evaluation of Brassica growth in the field using conditional generative adversarial networks. Computers and Electronics in Agriculture 190: 106415

Siegmann B, Cendrero-Mateo MP, Cogliati S, Damm A, Gamon J, Herrera D, Jedmowski C, Junker-Frohn LV, Kraska T, Muller O, Rademske P, van der Tol C, Quiros-Vargas J, Yang P, Rascher U (2021): Downscaling of far-red solar-induced chlorophyll fluorescence of different crops from canopy to leaf level using a diurnal data set acquired by the airborne imaging spectrometer HyPlant. Remote sensing of Environment 264: 112609

Genzel F, Dicke MD, Neuwohner A, Thiele B, Wormit A, Putz A, Junker-Frohn LV, Usadel B, Wormit A, Wiese-Klinkenberg (2021): Impact of moderate cold and high salt stress on the accumulation of antioxidant flavonoids in leaves of two contrasting Capsicum cultivars. Journal of Agricultural and Food Chemistry 69 (23): 6431–6443.

Junker-Frohn LV, Lueck M, Schmittgen S, Wensing J, Carraresi L, Thiele B, Groher T, Reimer JJ, Bröring S, Noga G, Jupke A, Schurr U, Usadel B, Wiese-Klinkenberg A, Wormit A (2019): Tomato’s green gold: Bioeconomy potential of residual leaf biomass as a novel source for secondary metabolites. ACS Omega 4: 19071−19080.

Junker-Frohn LV, Kleiber A, Jansen K, Gessler A, Kreuzwieser J, Ensminger I (2019): Differences in isoprenoid-mediated energy dissipation pathways between coastal and interior Douglas-fir seedlings in response to drought. Tree physiology 39 (10): 1750–1766.

Duan Q, Kleiber A, Jansen K, Junker-Frohn LV, Kammerer B, Han G, Zimmer I, Rennenberg H, Schnitzler JP, Ensminger I, Gessler A, Kreuzwieser J (2019): Effects of elevated growth temperature and enhanced atmospheric vapour pressure deficit on needle and root terpenoid contents of two Douglas fir provenances. Environmental and Experimental Botany 166: 103819.

Du B, Kreuzwieser J, Dannenmann M, Kleiber A, Eiblmeier M, Junker LV, Jansen K, Ensminger I, Gessler A, Kohnle U, Rennenberg H, Wildhagen H (2018): Foliar nitrogen metabolism of adult Douglas fir trees is affected by soil water availability and varies little among provenances. PLOS ONE 13 (3): e0194684.

Kleiber A, Duan Q, Jansen K, Junker LV, Kammerer B, Rennenberg H, Ensminger I, Gessler A, Kreuzwieser J (2017): Drought effects on root and needle terpenoid content of a coastal and an interior Douglas fir provenance. Tree physiology 37 (12): 1648–1658.

Junker LV, Kleiber A, Jansen K, Wildhagen H, Hess M, Kayler Z, Kammerer B, Schnitzler JP, Kreuzwieser J, Gessler A, Ensminger I (2017): Variation in short-term and long-term responses of photosynthesis and isoprenoid-mediated photoprotection to soil water availability in four Douglas-fir provenances. Scientific reports 7 : 40145.

Junker LV and Ensminger I (2016): Fast detection of leaf pigments and isoprenoids for ecophysiological studies, plant phenotyping and validating remote-sensing of vegetation. Physiologia Plantarum 158 (4): 369–381.

Hess M, Wildhagen H, Junker LV, Ensminger I (2016): Transcriptome responses to temperature, water availability and photoperiod are conserved among mature trees of two divergent Douglas-fir provenances from a coastal and an interior habitat. BMC Genomics 17: 682.

Junker LV and Ensminger I (2016): Relationship between leaf optical properties, chlorophyll fluorescence and pigment changes in senescing Acer saccharum leaves. Tree Physiology 36 (6): 694-711.

Fréchette E, Wong CYS, Junker LV, Chang CY and Ensminger I (2015): Zeaxanthin-independent energy quenching and alternative electron sinks cause a decoupling of the relation between the photochemical reflectance index (PRI) and photosynthesis in an evergreen conifer during spring. Journal of Experimental Botany 66 (22): 7309-7323.

Du B, Jansen K, Junker LV, Eiblmeier M, Kreuzwieser J, Gessler A, Ensminger I, Rennenberg H (2014): Elevated temperature differently affects foliar nitrogen partitioning in diverse Douglas fir provenances. Tree physiology 34 (10): 1090-1101