植物の成長を調節する新たな仕組みを解明 －高収量・環境ストレス耐性品種の開発につながる可能性－

• Using AirID, we searched for a new factor that works in cooperation with the protein DELLA, which suppresses plant growth, and discovered the histone modification enzyme HAC1.
• DELLAとHAC1が協力して遺伝子の発現を調節し、植物の成長を制御していることを明らかにしました。
• 成長を抑える遺伝子「ERF2” and clarified the mechanism by which DELLA suppresses plant growth via ERF2.
• 本研究成果は、植物の成長や環境応答を制御する仕組みの理解を深めるものであり、将来的には収量性と環境ストレス耐性を兼ね備えた農作物の品種改良への応用が期待されます。

The research group of Associate Professor Jutaro Fukasawa, graduate student Hiroki Ando, and Professor Emeritus Yosuke Takahashi of the Graduate School of Integrated Life Sciences, Hiroshima University, is led by Associate Professor Akira Nozawa, Professor Tatsuya Sawazaki of the Ehime University Institute of Advanced Research Proteoscience Center, In collaboration with Professor Hidetaka Kosako of the Institute of Advanced Enzymology, Tokushima University, we discovered a new growth control mechanism in which the protein DELLA, which suppresses plant growth, works in cooperation with the histone acetyltransferase HAC1. In this study, we identified HAC1 as an interacting factor of DELLA, which is a suppressor of gibberellin signal transduction, and clarified the mechanism by which the GAF1-DELLA-HAC1 complex activates transcription of target genes through histone modification. In addition, growth suppressor genesERF2We discovered DELLA as a new GAF1 target gene and elucidated the mechanism by which DELLA suppresses plant growth through regulating its expression (Figure 1). This year marks the 100th anniversary of the discovery of gibberellins, and the results of this research reveal a new mechanism that will greatly advance our understanding of the growth control mechanism by gibberellins.
The results of this research were published in the international academic journal "The Plant Cell" on August 11, 2020 (Japan time).

掲載雑誌名：The Plant Cell
掲載日：2026年8月11日
タイトル：DELLA proteins interact with HAC1 and control plant growth via transcriptional regulation of the growth repressor geneERF2
著者：Hiroki Ando、Akira Nozawa、Hidetaka Kosako、Tatsuya Sawasaki、Yohsuke Takahashi、Jutarou Fukazawa
(Hiroshi Ando, ​​Akira Nozawa, Hidetaka Kosako, Tatsuya Sawazaki, Yosuke Takahashi, Jutaro Fukasawa)
DOI：10.1093/plcell/koag235

本研究は、以下のサポートを受けて実施されました。科学研究費補助金：23K05818、内藤記念科学奨励金・研究助成、大隅基礎科学創成財団・研究助成、愛媛大学プロテオサイエンスセンター共同利用・共同研究拠点 PRiME、徳島大学先端酵素学研究所　共同利用・共同研究拠点、JST次世代研究者挑戦的研究プログラム　JPMJSP2132

ジベレリン(GA)*1is a plant hormone that promotes plant germination, elongation, flowering, etc. GA was discovered by Eiichi Kurosawa in 1926, and was subsequently isolated and named by Teijiro Yabuta and others. DELLA, a plant-specific protein, in GA signaling※2acts as a major suppressor. It is known that when plants are exposed to environmental stress, the amount of GA in the body decreases, and DELLA accumulates, suppressing growth. So far, GAF1 has been identified as a transcription factor that interacts with DELLA, and the GAF1-DELLA complex is responsible for the transcription of target genes.*3を活性化することが報告されていました。しかし、DELLAがどのような分子機構によって転写を活性化するのかは明らかになっていませんでした。また、DELLAが蓄積した植物では成長が抑制されることから、GAF1-DELLA複合体の標的遺伝子には成長抑制に関わる因子が含まれていると考えられていました。本研究では、ジベレリン量が低下すると、DELLAとHAC1が結合し、ERF2遺伝子の発現を促進することで植物の成長が抑制されることを明らかにしました。

本研究では、近位依存性ビオチン化酵素AirIDを用いて、DELLAタンパク質との相互作用因子を探索し、ヒストンアセチル基転移酵素HAC1を新たなDELLA相互作用因子として同定しました(図2)。HAC1がGAF1-DELLA複合体による転写活性化に関与しているのかを調べるため、hac1変異体におけるGAF1複合体標的遺伝子の発現量を解析した結果、野生型植物と比較してhac1変異体ではDELLA蓄積時に観察されるGAF1標的遺伝子の発現量増加が抑制されていました。さらに、HAC1抗体、およびヒストンH3のアセチル基を認識する抗体を用いたChIP(クロマチン免疫沈降)解析*4Therefore, HAC1 is recruited to the promoters of GAF1 target genes in a DELLA accumulation-dependent manner, and is associated with acetylation modification of histone H3.*5It was revealed that this was promoted (Figure 3).
Accumulation of DELLA promotes the expression of GAF1 target genes while suppressing plant growth. Based on this, it was thought that some of the GAF1 target genes contain factors that suppress growth. As a result of searching for new target genes in this study, transcription factorsETHYLENE RESPONSE FACTOR2(ERF2) was identified as a novel GAF1 target gene.ERF2We used CRISPR-Cas9 genome editing technology to investigate whether this gene functions as a growth-suppressing gene.erf2deletion mutants andERF2We created an overexpressor and observed the phenotype.erf2欠損変異体は野生型植物と比べて成長が促進され、ERF2過剰発現体は成長が抑制されたことから、ERF2が成長抑制遺伝子として機能することを明らかにしました(図4)。さらに、ERF2の発現制御も、他のGAF1標的遺伝子と同様に、DELLA-HAC1を介したヒストンのアセチル化修飾が関与することを明らかにしました。
These results suggest that the GAF1-DELLA-HAC1 ternary complex is formed during DELLA accumulation, and is a growth-suppressing gene through histone acetylation modification.ERF2It was revealed that GAF1 suppresses plant growth by promoting the transcription of GAF1 target genes, including .

Since the DELLA protein is a factor that is widely conserved in land plants, it is possible that similar growth control mechanisms exist not only in Arabidopsis, the model plant used in this study, but also in many agricultural crops. During the Green Revolution that occurred in the 1960s, the yield of grains such as rice and wheat was dramatically improved through the breeding of semi-dwarf varieties that utilized mutations in genes involved in gibberellin (GA) signal transduction, which greatly contributed to the increase in global food production. To date, we have shown that the GAF1-DELLA complex is involved in GA biosynthesis and the regulation of flowering by GA, but the new regulatory mechanism of the DELLA protein revealed in this study may provide a new molecular basis for more precisely controlling plant growth and environmental responses. In the future, if a similar mechanism is clarified in agricultural crops, it is expected that it will be applied to sustainable agriculture, such as the breeding of new varieties that have both high yield and environmental stress resistance.

※1 ジベレリン(GA)
植物の発芽、伸長成長、花成などを促進する植物ホルモン。

*2 DELLA protein
緑の革命で利用された半矮性化の原因遺伝子の1つ。GA信号伝達の抑制因子であり、植物の成長を抑制する「ブレーキ役」として機能します。GAが合成されるとDELLAタンパク質が分解され、成長のブレーキが解除されることで植物の成長が促進される。植物の成長を調節する中心的な因子として知られている。

*3 Transcription
The process of copying genetic information recorded in DNA to RNA. Proteins are synthesized based on the transcribed RNA.

*4 ChIP (chromatin immunoprecipitation) analysis
An experiment that uses an antibody against a target protein to verify whether the protein binds to the promoter or coding region of the target gene. It can be clarified whether the target protein binds to the target region directly or by forming a complex in vivo.

*5 Histone acetylation modification
Histones are proteins that wrap DNA and store it inside the nucleus. When an acetyl group is attached to a specific amino acid (lysine) in histones, DNA becomes looser, making it easier to read genetic information and thus increasing transcription.