Photosynthesis: Genetic Strategies Adopted to Gain Higher Efficiency.

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.

A Systemic View of Carbohydrate Metabolism in Rice to Facilitate Productivity.

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.

Heat stress transcription factor OsSPL7 plays a critical role in reactive oxygen species balance and stress responses in rice.

The rice spotted leaf gene, OsSPL7, induces lesion mimic (LM) spots under heat stress. Herein, we provide several lines of evidence elucidating the importance of OsSPL7 in maintaining reactive oxygen species (ROS) balance via the regulation of downstream gene expression. osspl7 knockout (spl7ko) mutants showed LM and growth retardation. Transgenic rice lines strongly overexpressing OsSPL7 (SPL7OX-S) exhibited LM accompanied by accumulated H2O2, whereas moderate expressers of OsSPL7 (SPL7OX-M) did not, and neither of them exhibited severe growth defects. Transient expression of OsSPL7-GFP in rice protoplasts indicated that OsSPL7 localizes predominantly in the nucleus. Transcriptional activity assay suggested its function as a transcriptional activator in rice. Disease evaluation showed that both SPL7OX and spl7ko enhanced resistance to Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae, the causal agents of blast and blight diseases in rice, respectively. Additionally, SPL7OX enhanced tolerance to cold stress, whereas spl7ko showed a phenotype opposite to the overexpression lines. RNA sequencing analyses identified four major groups of differentially expressed genes associated with LM, pathogen resistance, LM-pathogen resistance, and potential direct targets of OsSPL7. Collectively, our results suggest that OsSPL7 plays a critical role in plant growth and balancing ROS during biotic and abiotic stress.