Professor Kenji Miura in the Institute of Life and Environmental Sciences at the University of Tsukuba, and Team Director Motoaki Seki at the RIKEN Center for Sustainable Resource Science, announced that spraying ethanol during tomato cultivation confers heat stress tolerance and improves sugar content and vitamin C content. This cultivation method using inexpensive ethanol is expected to contribute to food production. The results were published in Scientific Reports on September 12.
In recent years, heat stress caused by climate change has seriously affected crop growth and yield. Challenges include the time and cost required for practical application of selective breeding and genetic modification technologies that enhance heat tolerance.
The research group had previously demonstrated that the tomato mutant phyA, which lacks phytochrome A, one of the photoreceptors, exhibits better heat stress tolerance during the vegetative growth stage compared with the wild type. However, this tolerance was not fully expressed during the reproductive growth stage, presenting a challenge for maintaining fruit quality.
Therefore, in this study, the researchers focused on ethanol spraying, which had been reported to enhance tolerance to environmental stresses such as drought and salt damage, as a method to strengthen heat stress tolerance. They verified its effectiveness.
The cultivation environment consisted of harsh heat stress conditions in a summer greenhouse (approximately 50℃ during the day and 30℃ at night) and a closed cultivation room maintained at 37℃. Ethanol was sprayed regularly once a week during cultivation of the tomato phyA mutant. As a comparison, the plant growth regulator 4-CPA (4-chlorophenoxy acetic acid, a synthetic auxin), which is effective for heat stress tolerance, was also used.
Tomatoes sprayed with ethanol or 4-CPA showed increased plant height and stem thickness compared with untreated tomatoes and maintained overall healthy growth. Furthermore, sugar content (Brix) and vitamin C contents increased.
Analysis revealed that ethanol spraying enhanced the expression of genes encoding heat shock proteins and antioxidant enzyme genes (enzymes that detoxify reactive oxygen species generated within cells).
The expression of genes involved in plant hormone signal transduction, such as auxin and gibberellin, was also promoted. The function of these genes is believed to have brought about growth promotion and fruit quality improvement.
Miura commented: "This is the result of joint research with RIKEN. The effect of ethanol spraying increasing heat tolerance and sugar content is expected to be enhanced for the hot summers we have been experiencing recently. Since the ethanol concentration used is not high, it seems like it will be easy to use."
Journal Information
Publication: Scientific Reports
Title: Application of 4-CPA or ethanol enhances plant growth and fruit quality of phyA mutant under heat stress
DOI: 10.1038/s41598-025-17929-8
This article has been translated by JST with permission from The Science News Ltd. (https://sci-news.co.jp/). Unauthorized reproduction of the article and photographs is prohibited.