Functional copy number variation in SQUALENE EPOXIDASE-LIKE genes affects photosystem II efficiency in Arabidopsis

Bezouw, R. v.; Nguyen, T.-P.; Hoang, N. V.; Vincenzi, E.; Velthoven, R. v.; Zhang, H.; Gao, Y.; Zhang, W.; Jacobi, R.; de Snoo, B. C.; Reyes Marquez, F.; Vasquez Catala, L.; Iqbal, M.; Jansen, S.; Mumm, R.; Harbinson, J.; Keurentjes, J. J. B.; Aarts, M. G. M.

doi:10.1101/2023.09.21.558849

bioRxiv · 10.1101/2023.09.21.558849

Functional copy number variation in SQUALENE EPOXIDASE-LIKE genes affects photosystem II efficiency in Arabidopsis

Bezouw, R. v.·Nguyen, T.-P.·Hoang, N. V.·Vincenzi, E.·Velthoven, R. v.·Zhang, H.·Gao, Y.·Zhang, W.·Jacobi, R.·de Snoo, B. C.·Reyes Marquez, F.·Vasquez Catala, L.·Iqbal, M.·Jansen, S.·Mumm, R.·Harbinson, J.·Keurentjes, J. J. B.·Aarts, M. G. M.

View original source ↗Export metadata ↓

Abstract

In this study, we found a single quantitative trait locus for photosystem II efficiency ({Phi}PSII) in the Arabidopsis Ler-0 x Col-0 recombinant inbred line population. This locus on chromosome 5 is caused by genetic variation in a cluster of tandemly repeated SQUALENE EPOXIDASE-LIKE (SQE-like) genes, with unknown function. We show the QTL is caused by variation in the SQE5, SQE6 and SQE7 genes affecting {Phi}PSII in a dose-dependent manner, due to a combination of functional copies. Col-0 carries only one functional copy, SQE5, while Ler-0 carries functional copies of SQE6 and SQE7. Overexpression of a functional copy of SQE6 enhances {Phi}PSII to exceed that of the Ler-0 parent in Arabidopsis, but does not affect {Phi}PSII in tobacco. Phylogenetic analysis of the SQE and SQE-likes in 135 plant species revealed that the SQE-likes are evolutionary confined to two sister families, the Cleomaceae and Brassicaceae, and diversified independently. The tandem cluster of four SQE-like genes in Arabidopsis is likely the result of two recent gene duplication events, one generating SQE5 from SQE4, the next one generating SQE6 and SQE7 from SQE5. The involvement of SQE-like genes in photosynthesis will open up new avenues to determine the function of these novel genes.

Explore related subjects

plant biology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Bezouw, R. v., Nguyen, T.-P., Hoang, N. V., Vincenzi, E., Velthoven, R. v., Zhang, H., Gao, Y., Zhang, W., Jacobi, R., de Snoo, B. C., Reyes Marquez, F., Vasquez Catala, L., Iqbal, M., Jansen, S., Mumm, R., Harbinson, J., Keurentjes, J. J. B., Aarts, M. G. M.. 2023-09-21. Functional copy number variation in SQUALENE EPOXIDASE-LIKE genes affects photosystem II efficiency in Arabidopsis. https://doi.org/10.1101/2023.09.21.558849

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

In-cell structural analysis reveals a distinctive chloroplast ribosome in Chlamydomonas reinhardtii

Chloroplast ribosomes synthesize plastid-encoded components of photosynthetic machinery, yet their structure and organization remain poorly understood. We combined cryo-focused ion beam milling, cryo-electron tomography and subtomogram averaging to determine native chloroplast ribosomes in Chlamydomonas reinhardtii. The 4.4-4.9 [A] structure revealed a large arch-like extension on the small subunit (SSU). Comparisons with bacterial and plant chloroplast ribosomes, supported by proteomics, AlphaFold3 predictions and a recent atomic model, indicate that the arch is formed by insertions and extensions in SSU proteins. Classification resolved active, thylakoid-associated ribosomes with density adjacent to the nascent peptide exit and an arch-moved state enriched among thylakoid-associated particles, with coordinated displacement of the arch and beak. Phylogenetic analysis revealed an evolutionary mosaic: the uS3c insertion is broadly distributed across Chlorophyceae, whereas the uS2c insertion, uS5c and PSRP7 are concentrated in Chlamydomonadales, with PSRP7 also in Sphaeropleales. Nuclear-encoded components were recruited stepwise onto a plastid-encoded scaffold, with all four under comparable purifying selection. These findings link a lineage-specific SSU extension to ribosome dynamics, thylakoid association and evolution, highlighting the value of in-cell structural analysis.

plant biology↗

bioRxiv2026

Implementation and calibration of the Vaganov-Shashkin model in the virtualRings R package

Process-based tree growth models provide a mechanistic framework for investigating how climate conditions regulate tree growth across daily to annual time scales. Yet, their broader application across species and environments is constrained by the limited accessibility in open-source environments and the difficulty of estimating physiological parameters that are rarely measured directly. Here, we present virtualRings, a new R package integrating the Vaganov-Shashkin model (VSM) and the RINGS3 models, and focus on the implementation and calibration of VSM. Using tree-ring width observations from seven Northern Hemisphere sites across various environmental conditions, we compared the traditional bootstrap-based calibration approach with the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). CMA-ES improved agreement between simulated and observed radial tree growth and provided an efficient approach for model parameter estimation. We further evaluated practical CMA-ES settings to balance computational cost and performance and discussed its potential limitations. The virtualRings package provides an open and reproducible platform for tree growth simulation, facilitating the application of important process-based models across species and environments and the investigation of how temperature and moisture constraints regulate daily tree-ring formation across spatial and temporal scales.

plant biology↗

bioRxiv2026

Timing of transient darkness shapes carbon-nitrogen metabolism and sugar signaling in sugarcane

Fluctuating light is common in field environments. Yet, the mechanisms by which C4 crops coordinate carbon and nitrogen metabolism during short-term carbon deprivation remain poorly understood. Here, we imposed transient darkness at different phases of the diel cycle to assess how the timing of light loss affects photosynthesis, carbohydrate turnover, amino acid dynamics, and sugar-sensing pathways in commercial sugarcane leaves. Early-day darkness significantly impaired photosynthetic induction and revealed a temporal disconnect between stomatal and metabolic limitations, whereas midday and late-day treatments caused temporary, time-specific disruptions in carbon assimilation. These shifts altered the balance between sucrose preservation and catabolic mobilization, leading to treatment-dependent changes in starch reserves and free amino acids. Core circadian components largely maintained their phase relationships, but their amplitudes varied across treatments, consistent with partial decoupling from carbon status. Darkness also reorganized energy signaling, with SnRK1 and DIN6 responses associated with greater declines in sucrose. Notably, trehalose-pathway transcripts showed marked changes in network connectivity, with ScTPSIIG consistently emerging as a highly connected candidate associated with photosynthetic performance, water-use traits, sugar sensing, and amino acid metabolism. Overall, these results indicate that the timing of carbon limitation and residual sucrose availability shape distinct metabolic responses, while trehalose metabolism provides a candidate regulatory layer coordinating carbon-nitrogen adjustment during the diel cycle, highlighting class II TPS proteins as targets for functional investigation of metabolic resilience in sugarcane.

plant biology↗