Heritable Genetic Architecture of Dynamic Photoprotection and NPQ Kinetics in Field-Grown Sorghum

  • SorghumBase Team
  • 31 March 2026

Field evaluation of a large sorghum diversity panel revealed heritable, environmentally responsive variation in NPQ capacity and kinetics, and integrative genomic analyses identified polygenic candidate loci—many linked to redox regulation, stress signaling, and photosynthetic control—that provide targets for improving photoprotection and photosynthetic efficiency in C4 crops.

Keywords: NPQ, crop genomics, dynamic light, high‐throughput phenotyping, photoprotection, photosynthesis, sorghum

By revealing substantial, heritable variation in the kinetics of non-photochemical quenching in field-grown sorghum, this study suggests that, despite a complex underlying genetic architecture, breeding or modification aimed at improving dynamic photoprotection may represent a promising target for increasing photosynthetic efficiency and stress resilience in C₄ crops. – Vath

Optimizing non‐photochemical quenching (NPQ) to better match fluctuating light environments represents a promising strategy to improve photosynthetic efficiency in crops. Scientists from University of Cambridge, University of Arkansas, Cornell University, University of Nebraska-Lincoln, University of Illinois Urbana-Champaign and University of Essex evaluated a large, field‐grown sorghum diversity panel over two growing seasons, revealing substantial and heritable intraspecific variation in NPQ capacity and kinetics. Maximum NPQ values and dynamic parameters such as induction and relaxation rate constants exhibited medium‐to‐high heritability and significant interannual correlations, despite environmental plasticity driven by differences in irradiation and water availability. The 2017 season, characterized by higher cumulative radiation and lower early‐season precipitation, showed faster NPQ induction, slower relaxation, and elevated residual NPQ, consistent with a more strongly “primed” photoprotective state and greater photoinhibition. Notably, NPQ relaxation kinetics were positively correlated with PSII recovery rates and lower photoinhibition, indicating that the speed of NPQ modulation—rather than maximum NPQ amplitude—may be a stronger determinant of photoprotection under transient high light. Although environmental effects influenced trait distributions, accession rank order was largely maintained across years, supporting the use of genomic approaches to dissect genetic control and identify elite germplasm for breeding.

An ensemble strategy integrating genome‐wide association studies (GWAS), transcriptome‐wide association studies (TWAS), and fluorescence covariance analyses identified a complex, polygenic architecture underlying NPQ traits, with nearly 40 loci influencing multiple photoprotective and photochemical parameters. Candidate genes included orthologs associated with redox regulation, antioxidant metabolism, ATP synthase activation, strigolactone biosynthesis, cuticular wax formation, jasmonic acid pathways, and chloroplast lipocalin–mediated sustained NPQ. Many candidates contained predicted nonsynonymous substitutions, suggesting coding variation contributes to heritable phenotypic diversity, potentially reflecting adaptation to diverse climatic origins. The predominance of genes linked to stress response and photosynthetic control underscores the tight integration between redox homeostasis, energy dissipation, and dynamic photosynthetic regulation. These findings provide a high‐confidence set of targets for functional validation and genomic selection, supporting the feasibility of manipulating NPQ kinetics to enhance photosynthetic efficiency and stress resilience in sorghum and related C4 crops.

SorghumBase Examples: 

Figure 1: A Gene Ontology search for the term nonphotochemical quenching (NPQ) returns many results, but none for sorghum species. Despite this lack of ontology mapping, users can identify sorghum orthologs by selecting the Homology tab and expanding the Andropogoneae tab to see the phylogenetic tree. Alternatively they can select the Gene Tree | Orthologs button at the bottom of the Homology display to return a new results window with all orthologs to the rice protein.
Figure 2: An eFP browser display for SORBI_3003G418000, which the authors identified as being associated with multiple NPQ traits. The eFP browser shows the gene expression activity is higher on the upper portion of emerged leaves at 44 days after emergence (DAE), which approximately corresponds to when the authors sampled leaf tissues in the field trials.
Reference:

Vath RL, Fernandes SB, Monier B, Głowacka K, Walter J, Lipka AE, Ferguson J, Bernacchi CJ, Pederson T, Kromdijk J. High-Throughput Screen of NPQ in Sorghum Shows Highly Polygenic Architecture of Photoprotection. Plant Environ Interact. 2026 Jan 11;7(1):e70114. PMID: 41532032. doi: 10.1002/pei3.70114. Read more

 

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Sorghum field in Urbana (IL). Photo credit Johannes Kromdijk.
Chlorophyll fluorescence during NPQ induction for a set of sorghum leaf samples. Photo credit Johannes Kromdijk and Richard Vath.