An H3K9me2 demethylase encoded by Jumonji C domain-containing DT2 regulates drought tolerance in rice

Abstract Drought is a major environmental stress limiting global rice (Oryza sativa) production, emphasizing the vital requirement for understanding the genetic basis of drought tolerance. Here, we identified a Jumonji C (JmjC) domain-containing gene, DROUGHT TOLERANCE 2 (DT2), which encodes an H3K9me2 demethylase that regulates drought tolerance in rice. DT2 reduces the H3K9me2 methylation level at the bZIP transcription factor OsZIP26, thereby increasing its expression. OsZIP26 inhibits the abscisic acid (ABA) biosynthesis gene 9-CIS-EPOXYCAROTENOID DIOXYGENASE 2 (NCED2) by activating the basic helix–loop–helix (bHLH) transcription factor bHLH048. DT2 also interacts with the abscisic acid-stress–ripening-inducible 5 (ASR5) protein. ASR5 directly activates the expression of NCED2, and DT2 impairs the ASR5-mediated activation of NCED2. The suppression of NCED2 reduces endogenous ABA levels, resulting in weak drought tolerance in rice. In addition to identifying DT2 as a negative regulator of drought tolerance, our study highlights the role of this JmjC domain-containing protein in drought tolerance and its potential for breeding drought-tolerant rice cultivars.