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A research team led by Xu Qiutao and Zhang Jisen at Guangxi University（GXU） has recently reported new findings that shed light on how rice plants respond to drought at the epigenetic level. Their study, titled “Lysine β-hydroxybutyrylation as a drought-responsive epigenetic mark in rice,” has been published online in the international journal Cell Discovery. The research reveals that a specific histone modification—lysine β-hydroxybutyrylation (Kbhb)—plays an important regulatory role in enhancing drought tolerance in rice by activating the expression of drought-responsive genes.

Protein post-translational modifications are widely recognized as one of the key mechanisms governing cellular processes. In recent years, advances in mass spectrometry have enabled scientists to identify a growing range of such modifications beyond the classical ones such as acetylation and methylation. Among the newly discovered modifications are crotonylation and β-hydroxybutyrylation (Kbhb). While Kbhb has been extensively studied in animals, its biological functions in plants—particularly in relation to environmental stresses such as drought—have remained largely unexplored.

The GXU team found that drought stress triggers a significant increase in Kbhb modification levels in rice, including those occurring on histone proteins. Further analysis revealed that histone Kbhb is strongly associated with activating histone marks such as H3K4ac and H3K9ac, while showing weak or negative correlations with repressive marks like H3K9me2 and H3K9me3. This pattern suggests that Kbhb functions as an epigenetic signal linked to transcriptional activation.

To better understand how this modification influences gene activity under drought conditions, the researchers analyzed genome-wide changes in histone Kbhb during drought stress. Their results showed that drought exposure induces increased Kbhb modification at the chromatin regions of numerous genes. Integrating these data with RNA-seq analysis, the team identified 629 genes whose expression appears to be directly regulated by histone Kbhb modification. These include several well-known drought-responsive genes, such as SIPP2C1, HOX24, DIAT, and NF-YA76. The findings indicate that, under drought conditions, Kbhb modification promotes rice drought tolerance by activating the transcription of key stress-response genes.

Figure 1. Molecular mechanism by which histone β-hydroxybutyrylation regulates drought resistance in rice.

The study also explored how Kbhb modification itself is regulated during drought stress. Through screening for regulatory factors associated with Kbhb, the researchers identified the histone deacetylase HDA710 as a specific enzyme capable of removing Kbhb marks from histones. Both in vivo and in vitro biochemical experiments confirmed that HDA710 acts as a key negative regulator of this modification. Under drought conditions, loss of HDA710 function leads to the accumulation of Kbhb marks at drought-responsive gene loci, promoting transcriptional activation and ultimately enhancing the plant’s drought resistance.

By systematically elucidating the regulatory mechanism of Kbhb in rice under drought stress, this research expands current understanding of plant epigenetics and provides new theoretical insights that may support the future breeding of stress-resilient crop varieties.

This research was supported by several funding programs, including Guangxi Major Science and Technology Projects, the Bagui Young Talents Program, the Guangxi Outstanding Young Scientists Fund, and talent development initiatives of Guangxi University.