H3K9 demethylation-mediated transcriptional activation is required for male meiosis in Arabidopsis thaliana

Dimethylation at histone H3 lysine 9 (H3K9me2), a critical mark for heterochromatin formation and transcriptional silencing, is usually methylated at transposable elements and repetitive sequences but unmethylated at bodies of protein-coding genes. It is known that deposition of H3K9me2 is essential for proper prophase progression in both mammals and plants. Nevertheless, function of removing H3K9me2 for meiosis is unknown. In this study, we show that H3K9 demethylases, IBM1 and JMJ27, together regulate chromosome pairing and segregation in early meiosis, through protecting thousands of protein-coding genes from ectopic H3K9me2, including meiotic-essential genes. In addition to IBM1 and JMJ27, we also found that the cohesin complex cofactors Precocious Dissociation of Sisters 5 (PDS5s) regulate the expression of essential meiotic genes by interacting with H3K9 demethylases, acting downstream of H3K9 demethylation. Therefore, H3K9 demethylases and PDS5s coordinately regulate male meiosis through regulating the expression of meiotic-essential genes. These findings provide insights into a novel function of removing H3K9me2 for meiosis and deeper understanding of the H3K9 demethylation-mediated transcriptional activation pathway. We compared the transcriptomes and genome profiles of H3K9me2 for Col, ibm1, ibm1 jmj27, and pds5.