The global challenge of feeding an ever-increasing population to maintain food security requires novel approaches to increase crop yields. Photosynthesis, the fundamental energy and material basis for plant life on Earth, is highly responsive to environmental conditions. Evaluating the operational status of the photosynthetic mechanism provides insights into plants’ capacity to adapt to their surroundings. Despite immense effort, photosynthesis still falls short of its theoretical maximum efficiency, indicating significant potential for improvement. In this review, we provide background information on the various genetic aspects of photosynthesis, explain its complexity, and survey relevant genetic engineering approaches employed to improve the efficiency of photosynthesis. We discuss the latest success stories of gene-editing tools like CRISPR-Cas9 and synthetic biology in achieving precise refinements in targeted photosynthesis pathways, such as the Calvin-Benson cycle, electron transport chain, and photorespiration. We also discuss the genetic markers crucial for mitigating the impact of rapidly changing environmental conditions, such as extreme temperatures or drought, on photosynthesis and growth. This review aims to pinpoint optimization opportunities for photosynthesis, discuss recent advancements, and address the challenges in improving this critical process, fostering a globally food-secure future through sustainable food crop production.

Sucrose functions as a signaling molecule in several metabolic pathways as well as in various developmental processes. However, the molecular mechanisms by which sucrose regulates these processes remain largely unknown. In the present study, we demonstrate that sucrose promotes flowering by mediating the stability of a regulatory protein that represses flowering in rice. Exogenous application of sucrose promoted flowering by inducing florigen gene expression. Reduction of sucrose levels in the phloem through genetic modifications, such as the overexpression of the vacuolar invertase OsVIN2 or the mutation of OsSUT2, a sucrose transporter, delayed flowering. Analysis of relative transcript levels of floral regulatory genes showed that sucrose activated Ehd1 upstream of the florigen, with no significant effect on the expression of other upstream genes. Examination of protein stability after sucrose treatment of major floral repressors revealed that the Ghd7 protein was specifically degraded. The Ghd7 protein interacted with the E3 ligase IPA INTERACTING PROTEIN1 (IPI1), and sucrose‐induced K48‐linked polyubiquitination of Ghd7 via IPI1, leading to protein degradation. Mutants defective in IPI1 delayed flowering, confirming its role in modulating proteins involved in flowering. We conclude that sucrose acts as a signaling molecule to induce flowering by promoting Ghd7 degradation via IPI1.

Carbohydrate metabolism is an important biochemical process related to developmental growth and yield-related traits. Due to global climate change and rapid population growth, increasing rice yield has become vital. To understand whole carbohydrate metabolism pathways and find related clues for enhancing yield, genes in whole carbohydrate metabolism pathways were systemically dissected using meta-transcriptome data. This study identified 866 carbohydrate genes from the MapMan toolkit and the Kyoto Encyclopedia of Genes and Genomes database split into 11 clusters of different anatomical expression profiles. Analysis of functionally characterized carbohydrate genes revealed that source activity and eating quality are the most well-known functions, and they each have a strong correlation with tissue-preferred clusters. To verify the transcriptomic dissection, three pollen-preferred cluster genes were used and found downregulated in the gori mutant. Finally, we summarized carbohydrate metabolism as a conceptual model in gene clusters associated with morphological traits. This systemic analysis not only provided new insights to improve rice yield but also proposed novel tissue-preferred carbohydrate genes for future research.

Cell wall invertases (CINs) establish sucrose gradients between source and sink tissues, essential for the allocation of photoassimilates. Rice possesses nine CIN genes, among which OsCIN1 and OsCIN2 have been reported as key regulators of sink strength. To test whether increasing CIN activity enhances grain yield, we generated OsCIN1 overexpression lines in rice driven by the CaMV 35S promoter. Subcellular localization analysis of OsCIN1–GFP confirmed its apoplastic localization. OsCIN1 promoter::GUS analyses verified expression in vascular tissues and revealed predominant signals in the ovular vascular and lateral stylar vascular traces during seed development. Although CIN activity was markedly elevated throughout the plant, the resulting phenotypes were unexpected. Sugar profiling of flag leaves at the flowering stage showed almost complete sucrose depletion in the overexpression (OX) lines, accompanied by increased hexose and starch accumulation. Under field conditions, OsCIN1 OX plants exhibited ~50% fewer tillers and a lower 1000-grain weight relative to wild type (WT), resulting in reduced productivity. Ectopic expression of OsCIN1 disrupted the sucrose concentration gradient, weakened carbon partitioning to sink tissues, and impaired key agronomic traits. Collectively, sugar flux is governed by the spatiotemporal patterning of CINs, highlighting that precise spatial and temporal control of CIN activity is required to increase yield.