AGAMOUS-LIKE67 Cooperates with the Histone Mark Reader EBS to Modulate Seed Germination under High Temperature.

Area of Science:

• Plant biology
• Molecular genetics
• Epigenetics

Background:

• Seed germination is crucial for plant establishment and regulated by environmental cues.
• High temperatures (HT) induce thermoinhibition, suppressing germination via hormonal changes (ABA/GA).
• The SOMNUS (SOM) protein is involved in thermoinhibition, but its regulatory mechanism is unclear.

Purpose of the Study:

• To elucidate the molecular mechanism by which SOM regulates seed germination under high temperatures.
• To identify key factors involved in SOM-mediated thermoinhibition.

Main Methods:

• Analysis of SOM promoter binding and trans-activation in Arabidopsis.
• Identification of transcription factors interacting with the SOM promoter.
• Chromatin immunoprecipitation (ChIP) to assess protein enrichment and histone modifications at the SOM locus.

Main Results:

• SOM activates its own expression by binding to its promoter.
• AGAMOUS-LIKE67 (AGL67) binds to CArG-boxes in the SOM promoter and mediates its activation under HT.
• AGL67 recruits EARLY BOLTING IN SHORT DAY (EBS), a histone mark reader, to the SOM promoter.
• The AGL67-EBS complex promotes H3K4me3 recognition and H4K5 acetylation, leading to SOM activation and germination inhibition under HT.

Conclusions:

• AGL67 and EBS form a complex that epigenetically activates SOM expression under high temperatures.
• This epigenetic activation of SOM is a key mechanism suppressing seed germination during heat stress.
• The findings reveal a novel regulatory pathway linking environmental signals to gene expression and plant development.