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Strigolactone (SL) is a plant hormone required for plant development. DWARF53 (D53) functions as a transcription repressor in SL signaling. However, the role of D53 in cotton (Gossypium hirsutum, Gh) fiber development remains unclear. Here, we identify that GhD53 suppresses fiber elongation by repressing transcription of GhFAD3 genes, which control linolenic acid (C18:3) biosynthesis. Mechanistically, GhD53 interacts with SL-related transcriptional activate factor (GhSLRF) to prevent its binding on Omega-3 fatty acid desaturase gene (GhFAD3) promoters, thereby inhibiting GhFAD3 transcription. Upon SL exposure, GhD53 is degraded and leads to GhSLRF activation. This activation further promotes GhFAD3 transcription, C18:3 biosynthesis, and fiber elongation. Our findings identify the molecular mechanism of how SL controls cell elongation via D53 and offer potential strategies to improve cotton quality through SL application. 

The starch metabolic network was investigated in relation to other metabolic processes by examining a mutant with altered single-gene expression of ATP citrate lyase (ACL), an enzyme responsible for generating cytosolic acetyl-CoA pool from citrate. Previous research has shown that transgenic antisense plants with reduced ACL activity accumulate abnormally enlarged starch granules. In this study, we explored the underlying molecular mechanisms linking cytosolic acetyl-CoA generation and starch metabolism under short-day photoperiods. We performed transcriptome and quantification of starch accumulation in the leaves of wild-type and antisense seedlings with reduced ACL activity. The antisense-ACLA mutant accumulated more starch than the wild type under short-day conditions. Zymogram analyses were conducted to compare the activities of starch-metabolizing enzymes with transcriptomic changes in the seedling. Differential expression between wild-type and antisense-ACLA plants was detected in genes implicated in starch and acetyl-CoA metabolism, and cell wall metabolism. These analyses revealed a strong correlation between the transcript levels of genes responsible for starch synthesis and degradation, reflecting coordinated regulation at the transcriptomic level. Furthermore, our data provide novel insights into the regulatory links between cytosolic acetyl-CoA metabolism and starch metabolic pathways. 

We demonstrate two synthetic single-cell systems that can be used to better understand how the acquisition of an orphan gene can affect complex phenotypes. The Arabidopsis orphan gene,Qua-Quine Starch(QQS) has been identified as a regulator of carbon (C) and nitrogen (N) partitioning across multiple plant species.QQSmodulates this important biotechnological trait by replacing NF-YB (Nuclear Factor Y, subunit B) in its interaction with NF-YC. In this study, we expand on these prior findings by developingChlamydomonas reinhardtiiandSaccharomyces cerevisiaestrains, to refactor the functional interactions between QQS and NF-Y subunits to affect modulations in C and N allocation. Expression ofQQSinC. reinhardtiimodulates C (i.e., starch) and N (i.e., protein) allocation by affecting interactions between NF-YC and NF-YB subunits. Studies inS. cerevisiaerevealed similar functional interactions between QQS and the NF-YC homolog (HAP5), modulating C (i.e., glycogen) and N (i.e., protein) allocation. However, inS. cerevisiaeboth the NF-YA (HAP2) and NF-YB (HAP3) homologs appear to have redundant functions to enable QQS and HAP5 to affect C and N allocation. The genetically tractable systems that developed herein exhibit the plasticity to modulate highly complex phenotypes. 

Summary Genome editing is a revolution in biotechnology for crop improvement with the final product lacking transgenes. However, most derived traits have been generated through edits that create gene knockouts.Our study pioneers a novel approach, utilizing gene editing to enhance gene expression by eliminating transcriptional repressor binding motifs.Building upon our prior research demonstrating the protein‐boosting effects of the transcription factor NF‐YC4, we identified conserved motifs targeted by RAV and WRKY repressors in theNF‐YC4promoters from rice (Oryza sativa) and soybean (Glycine max). Leveraging CRISPR/Cas9 technology, we deleted these motifs, resulting in reduced repressor binding and increasedNF‐YC4expression. This strategy led to increased protein content and reduced carbohydrate levels in the edited rice and soybean plants, with rice exhibiting up to a 68% increase in leaf protein and a 17% increase in seed protein, and soybean showing up to a 25% increase in leaf protein and an 11% increase in seed protein.Our findings provide a blueprint for enhancing gene expression through precise genomic deletions in noncoding sequences, promising improved agricultural productivity and nutritional quality.