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Abstract Tolerance of chilling dictates the geographical distribution, establishment, and productivity of C4crops. Chilling reduces enzyme rate, limiting the sink for the absorbed light energy leading to the need for quick energy dissipation via non-photochemical quenching (NPQ). Here, we characterize NPQ upon chilling in threeMiscanthusaccessions representing diverse chilling tolerance in C4grasses. High chilling tolerant accessions accumulate substantial amounts of zeaxanthin during chilling nights in both field and growth chamber settings. Chilling-induced zeaxanthin accumulation in the dark enhances rate of NPQ induction by 66% in the following morning. Based on our data, the emerging ways for the unique regulation of NPQ include post-translational regulation of violaxanthin de-epoxidase (VDE), VDE cofactor accessibility, and absence of transcriptional upregulation of zeaxanthin conversion back to violaxanthin. In the future, more studies will be required to obtain further evidence for these ways contributions to the chilling-dark regulation of NPQ. Engineering dark accumulation of zeaxanthin will help improve crop chilling tolerance and promote sustainable production by allowing early spring planting to maximize the use of early-season soil moisture. Driving the engineered trait by chilling inducible promoter would ensure the minimization of a trade-off between photoprotection and photosynthesis efficiency.
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This content will become publicly available on December 26, 2025
Genetic Basis of Non‐Photochemical Quenching and Photosystem II Efficiency Responses to Chilling in the Biomass Crop Miscanthus
ABSTRACT Miscanthusholds a promise as a biocrop due to its high yield, perenniality and ability to grow on infertile soils. However, the current commercial biomass production ofMiscanthusis mostly limited to a single sterile triploid clone ofM.×giganteus. Nevertheless, parental species ofM.×giganteus, MiscanthussacchariflorusandMiscanthussinensiscontain vast genetic diversity for crop improvement. WithM. sacchariflorushaving a natural geographic distribution in cold‐temperate northeast China and eastern Russia, we hypothesised that it has substantial variation in physiological response to chilling. Using a semi‐high‐throughput method, we phenotyped 209M. sacchariflorusgenotypes belonging to six genetic groups for non‐photochemical quenching (NPQ) and photosystem II efficiency (ΦPSII) kinetics under warm and chilling treatments in three growing seasons. In response to the chilling treatment, all genetic groups exhibited an increase in NPQ induction rate indicating faster activation of NPQ in light. Notably, under chilling, the Korea/NE China/Russia 2x and N China 2x groups stood out for the highest NPQ rate in light and the highest steady‐state NPQ in light. This NPQ phenotype may contribute adaptation to chilling during bright, cold mornings of spring and early autumn in temperate climates, when faster NPQ would better protect from oxidative stress. Such enhanced adaptation could expand the growing season and thus productivity at a given location or expand the range of economically viable growing locations to higher latitudes and altitudes. A genome‐wide association study identified 126 unique SNPs associated with NPQ and ΦPSII traits. Among the identified candidate genes were enzymes involved in the ascorbate recycle and shikimate pathway, gamma‐aminobutyric acid and cation efflux transporters. Identifying natural variation and genes involved in NPQ and ΦPSII kinetics considerably enlarges the toolbox for breeding and/or engineeringMiscanthuswith optimised photosynthesis under warm and chilling conditions for sustainable feedstock production for bioenergy. Chilling affects the productivity and geographical distribution of most crops. Using a semi‐high‐throughput approach to investigate photosynthesis‐related traits, we characterised variation existing in the bioenergy cropMiscanthusunder chilling and warm conditions and identified potential genes associated with it. Under chilling, two genetic groups from the northern edge ofMiscanthusdistribution stood out for faster activation of photoprotection. This trait may contribute adaptation to chilling in temperate climates, when faster photoprotection would better defend from oxidative stress. Enhanced chilling adaptation could expand the growing season and thus productivity or enlarge the range of growing locations.
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- Award ID(s):
- 2142993
- PAR ID:
- 10574343
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- GCB Bioenergy
- Volume:
- 17
- Issue:
- 1
- ISSN:
- 1757-1693
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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