TY  - JOUR
AU  - Ye, Xiangyuan
AU  - Dong, Jianli
AU  - Wei, Shaobo
AU  - Li, Xia
AU  - Qian, Hongge
AU  - Zhou, Yujie
AU  - Gao, Yuan
AU  - Zhou, Yupeng
AU  - Cheng, Lin
AU  - Cheng, Long
AU  - Wang, Junyan
AU  - Wang, Liman
AU  - Xie, Chen
AU  - Li, Yefeng
AU  - Shang, Lianguang
AU  - Qian, Qian
AU  - Zhou, Wenbin
PY  - 2026
TI  - Rice fructokinases orchestrate carbon partitioning to regulate photosynthesis and sugar metabolism
JO  - The Crop Journal
SN  - 2095-5421
SP  - 710
EP  - 722
VL  - 14
IS  - 3
AB  - Fructokinases (FRKs) are key regulators in carbohydrate metabolism and plant development. However, their specific functions in crop photosynthesis and sugar metabolism remain unclear. In this study, we identified three rice FRKs (OsFRK1, OsFRK2, and OsFRK3), investigating their catalytic activities, expression pattern, and subcellular localization. OsFRK1 and OsFRK2 localized to the cytosol, whereas OsFRK3 localized to chloroplasts, indicating spatially distinct functions. Using CRISPR/Cas9, we generated single mutants (osfrk1, osfrk2, osfrk3) and a double mutant osfrk1×osfrk2 deficient in both cytosolic OsFRKs. All mutants showed significantly reduced plant height, biomass, and grain yield under field conditions. At the physiological level, OsFRK mutants displayed markedly reduced OsFRK enzyme activity, accompanied by impaired photosynthetic efficiency, excessive starch and fructose accumulation in leaves, and elevated sucrose and fructose levels in grains. Loss function of OsFRKs also triggered metabolic compensation in source leaves, including elevated activities of sucrose-degradation enzymes and hexokinase. Additionally, haplotype analysis identified elite alleles of OsFRKs: FRK1C (higher panicle number), FRK2C (greater 1000-grain weight), and FRK3A (higher panicle number). Cultivars carrying the combined haplotypes (FRK1C–FRK2C–FRK3A) exhibited higher grain yields than other genotype combinations. Together, these findings revealed cytosolic and chloroplastic OsFRKs in regulating rice photosynthesis, sugar allocation, and yield formation, and highlighted the elite OsFRK haplotypes as valuable genetic resources for future rice improvement.
UR  - https://doi.org/10.1016/j.cj.2025.12.002
DO  - 10.1016/j.cj.2025.12.002