CitRWP
directly activates
CsDAZ3
to promote somatic embryogenesis in
Citrus
Yin Zhou, Xietian Song, Nan Wang, Zhen Cao, Siqi Zhang, Zongzhou Xie, Lijun Chai, Xiaomeng Wu, Qiang Xu, Junli Ye, Fei Zhang, Xiuxin Deng Summary
Somatic embryogenesis (SE) serves as an ideal model for studying plant cell totipotency and embryonic development mechanisms, yet the transcriptional and epigenetic regulation underlying this process remains poorly characterized.
We found that citrus nucellar polyembryony (a form of apomixis) gene, RWP‐RK domain‐containing transcription factor (
CitRWP)
is highly expressed in embryogenic callus with strong SE capacity, and its expression is constantly upregulated during SE induction. Overexpression of
CitRWP
induced spontaneous somatic embryo formation in a citrus variety that is resistant to SE bypass exogenous inducer. Suppression of
CitRWP
expression by RNA interference (RNAi) impairs SE capacity. Integrated RNA‐seq and Chromatin immunoprecipitation sequencing (ChIP‐seq) analyses combined with molecular assays revealed that CitRWP directly binds to the
DUO1‐ACTIVATED ZINC FINGER 3
(
CsDAZ3)
promoter and activates its transcription. Overexpression of
CsDAZ3
significantly enhanced SE capacity.
Comparative analysis of ChIP‐seq and ATAC‐seq (Assay for Transposase‐Accessible Chromatin using sequencing) datasets demonstrated that CitRWP is capable of binding to regions of low chromatin accessibility. CitRWP binds to a condensed chromatin site in the
CsDAZ3
promoter and promotes increased local chromatin accessibility at the
CsDAZ3
locus.
Our findings delineate a novel regulatory framework for citrus SE, highlighting that
CitRWP
coordinates transcriptional regulation with chromatin remodeling. This research provides insights into plant cell reprogramming and provides pivotal molecular targets for optimizing breeding protocols by modulating SE.