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Peer-reviewedCC BY 4.0Frontiers in Plant Science

CRISPR/Cas9-mediated editing of SlALS1 enhances fruit sweetness in tomato

  • So Hee Yang1
  • Soon-Ki Han2
  • Yeonjong Koo1,3,4
4 affiliations
  1. 1Department of Agricultural Chemistry, Chonnam National University
  2. 2Department of Biological Sciences, Ajou University
  3. 3Institute of Environmentally-friendly Agriculture, Chonnam National University
  4. 4Institute of Plant Biomaterials and Biomedical Science, Chonnam National University
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Abstract

Fruit sweetness is a primary determinant of consumer preference and market value in tomato ( Solanum lycopersicum ), yet increasing sugar content without negatively affecting plant performance remains a major challenge in breeding programs. In this study, we targeted Acetolactate synthase 1 ( SlALS1 ), a key enzyme in branched-chain amino acids (BCAAs) biosynthesis, to investigate whether modulation of primary metabolism could enhance fruit sugar accumulation. Tomato contains two ALS homologs, SlALS1 and SlALS2 . Using CRISPR/Cas9-mediated genome editing, we generated SlALS1 knock-out lines in the Micro-Tom background. Loss of SlALS1 function led to a significant reduction in the levels of valine, leucine, and isoleucine in fruit tissues, confirming disruption of the BCAA biosynthetic pathway. Notably, soluble sugar content was markedly increased in the mutant lines, with glucose and fructose levels elevated by approximately 1.3-fold compared with wild-type fruits, resulting in a significantly higher Brix index. Metabolic profiling indicates that reduced BCAA biosynthesis may influence carbon allocation toward soluble sugar accumulation in fruit tissues, revealing an association between amino acid metabolism and carbohydrate accumulation during fruit development. Our findings demonstrate that precise editing of a central metabolic enzyme can enhance tomato fruit sweetness and suggest that SlALS1 may represent a promising target for genome editing aimed at improving fruit quality traits. However, further evaluation of agronomic traits, including plant growth and fruit yield, will be necessary to assess its potential for practical breeding applications.

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Cite

BibTeXRIS
BibTeX
@article{yang2026crisprcas9mediated,
  title = {{CRISPR/Cas9-mediated editing of SlALS1 enhances fruit sweetness in tomato}},
  author = {So Hee Yang and Soon-Ki Han and Yeonjong Koo},
  journal = {Frontiers in Plant Science},
  year = {2026},
  month = oct,
  doi = {10.3389/fpls.2026.1927332},
  url = {https://www.frontiersin.org/articles/10.3389/fpls.2026.1927332/full},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - CRISPR/Cas9-mediated editing of SlALS1 enhances fruit sweetness in tomato
AU  - So Hee Yang
AU  - Soon-Ki Han
AU  - Yeonjong Koo
PY  - 2026
DA  - 2026/10/08
JO  - Frontiers in Plant Science
DO  - 10.3389/fpls.2026.1927332
UR  - https://www.frontiersin.org/articles/10.3389/fpls.2026.1927332/full
AB  - Fruit sweetness is a primary determinant of consumer preference and market value in tomato ( Solanum lycopersicum ), yet increasing sugar content without negatively affecting plant performance remains a major challenge in breeding programs. In this study, we targeted Acetolactate synthase 1 ( SlALS1 ), a key enzyme in branched-chain amino acids (BCAAs) biosynthesis, to investigate whether modulation of primary metabolism could enhance fruit sugar accumulation. Tomato contains two ALS homologs, SlALS1 and SlALS2 . Using CRISPR/Cas9-mediated genome editing, we generated SlALS1 knock-out lines in the Micro-Tom background. Loss of SlALS1 function led to a significant reduction in the levels of valine, leucine, and isoleucine in fruit tissues, confirming disruption of the BCAA biosynthetic pathway. Notably, soluble sugar content was markedly increased in the mutant lines, with glucose and fructose levels elevated by approximately 1.3-fold compared with wild-type fruits, resulting in a significantly higher Brix index. Metabolic profiling indicates that reduced BCAA biosynthesis may influence carbon allocation toward soluble sugar accumulation in fruit tissues, revealing an association between amino acid metabolism and carbohydrate accumulation during fruit development. Our findings demonstrate that precise editing of a central metabolic enzyme can enhance tomato fruit sweetness and suggest that SlALS1 may represent a promising target for genome editing aimed at improving fruit quality traits. However, further evaluation of agronomic traits, including plant growth and fruit yield, will be necessary to assess its potential for practical breeding applications.
SN  - 1664-462X
ER  -