High-throughput phenotyping unlocks drought secrets in Norway spruce
image: (a) Principal component analysis (PCA) of metabolic profiles of studied provenances at different time points. Note the differences between treatments and time along PC1 and provenance differences on PC2. (b) Total phenolics (sum of 1021 features) contents in well-watered (WW) and drought-stressed (D) samples at four different time points. Asterisks indicate significant differences between treatments at respective time points assessed by t-test. P-values ∗ = P<0.05; ∗∗=P < 0.01; ∗∗∗ = P < 0.001. Error bars indicate the standard error of means. (n=3 technical replicates derived from the pool of 19–24 individuals per provenance, treatment, and time point). (c) Hierarchal cluster analysis of identified and annotated 43 phenolics compounds. (d) PCA of transcript profiles. (e) Venn diagram exhibits the number of shared and unique differentially expressed genes (DEG) (FDR <0.05) between provenances. The bar plots below the Venn diagram represent number of up-and downregulated DEG in each provenance with respect to well-watered seedlings. (f) Heatmap of DEG of ABA biosynthesis, signaling and photosynthesis pathways. The bold letters indicate significance for D1 exclusively in P2. For clarity only a subset of genes is shown from these pathways. A complete list is provided in Table S7.
Credit: The authors
Their findings highlight multilayered physiological, molecular, and metabolic adjustments that differentiate provenances and lay the foundation for identifying resilient populations better suited for future climates.
Drought is rapidly emerging as one of the most critical threats to Europe’s forests, accelerating tree mortality and undermining ecosystem services. For Norway spruce (Picea abies Karst L.)—which provides nearly half of Europe’s forest economic value—reduced summer precipitation already constrains growth and survival. Traditional provenance trials, based on measuring tree height and diameter, are slow, labor-intensive, and cover limited sites, making them unsuitable for the scale and urgency of current challenges. Rapid, non-invasive technologies that can capture multiple physiological traits in thousands of seedlings simultaneously are urgently needed. By combining multisensor imaging with “omics” tools, researchers can now move beyond basic growth measures to uncover the underlying biochemical and genetic mechanisms of drought tolerance.
A study (DOI: 10.1016/j.plaphe.2025.100037) published in Plant Phenomics on 31 March 2025 by Carlos Trujillo-Moya’s team, Austrian Research Centre for Forests BFW - Department of Forest Growth,
In this study, researchers employed a high-throughput phenotyping (HTPP) approach integrated with multisensor imaging—including RGB, 3D scanning, chlorophyll fluorescence (CHLF), and hyperspectral sensors (VNIR, SWIR)—to examine drought responses in two climatically contrasting Norway spruce provenances (P1 and P2) over a 21-day drought period. This method generated 56 traits capturing growth, photosynthesis, water status, and vegetation indices. Principal component analysis revealed that drought treatment accounted for the largest variance, driven by changes in PSII efficiency, growth, and tissue water content, while temporal progression of stress highlighted early photoprotective responses (non-photochemical quenching) and later PSII damage. Provenance-specific differences emerged, with P1 showing earlier activation of photoprotection and P2 exhibiting stronger declines in growth and photosynthetic efficiency, indicating distinct drought sensitivities. RGB imaging and 3D scanning confirmed growth inhibition under drought, with P2 more severely affected, and 3D measurements strongly correlated with manual assessments, validating their accuracy. CHLF imaging provided additional insight by distinguishing early and late drought stages, offering physiological explanations for observed growth reductions. Hyperspectral reflectance further revealed shifts in pigment and water status, with P1 showing earlier and stronger spectral changes, while vegetation indices like NDVI correlated with pigments such as zeaxanthin and β-carotene. Hormonal profiling demonstrated time-dependent increases in ABA, cytokinins, and auxin, linked to stomatal regulation and stress acclimation, with stronger hormonal fluctuations in P1. Metabolomics identified increases in zeaxanthin, lutein, α-tocopherol, and phenolics as protective metabolites, while transcriptomics revealed thousands of differentially expressed genes, with P2 showing a higher number and stronger downregulation of photosynthetic machinery, suggesting greater vulnerability. Finally, stem anatomical analyses showed significant reductions in xylem and phloem tissues under drought, with P2 again more affected, aligning with phenotypic data. Together, these results demonstrate that the multisensor HTPP approach effectively captures treatment, temporal, and genetic components of drought responses, offering a powerful framework to screen and identify resilient Norway spruce provenances.
This work establishes a robust, scalable framework for forestry research and breeding. By integrating imaging platforms with metabolomics and transcriptomics, scientists can identify early-stage physiological markers that predict long-term drought resilience. Such insights will help forest managers and breeders accelerate the selection of provenances with superior drought tolerance, strengthening Europe’s forestry sector against climate change. Beyond spruce, the methodology can be adapted to other tree species, closing the gap between genotype and phenotype in forest science.
###
References
DOI
Original URL
https://doi.org/10.1016/j.plaphe.2025.100037
Funding information
Financial support was provided by the Austrian Research Promotion Agency (FFG) and grant Nu. 2021–0.382.292 (project: climate smart forests: provenance selection and planting method_AP2) with funds from the departmental research program through dafne.at with resources from the Federal Ministry of Agriculture, Regions, and Water Management. The Federal Ministry supports applied, problem-oriented, and practice-oriented research within the competence area of the department. We acknowledge The Austrian Research Promotion Agency (FFG) - R&D Infrastructure Funding Programme - PHENOPlant project #870446″ for the PHENOPlant research infrastructure. The Vienna BioCenter Core Facilities (VBCF) Plant Sciences Facility acknowledges funding from the Austrian Federal Ministry of Education, Science & Research; and the City of Vienna. Further support was provided by the Austrian Science Funds FWF, projects P32203-B “Legacy effects after summer and winter drought” and DOC 171 “The future of mountain forests”.
About Plant Phenomics
Plant Phenomics is dedicated to publishing novel research that will advance all aspects of plant phenotyping from the cell to the plant population levels using innovative combinations of sensor systems and data analytics. Plant Phenomics aims also to connect phenomics to other science domains, such as genomics, genetics, physiology, molecular biology, bioinformatics, statistics, mathematics, and computer sciences. Plant Phenomics should thus contribute to advance plant sciences and agriculture/forestry/horticulture by addressing key scientific challenges in the area of plant phenomics.