GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE322nnn/GSE322771/primaryOK200TranscriptomicsArabidopsis thalianaExpression profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE322771GEOGSEfalseA host-co-opted Harbinger transposase engages multiple trihelix DNA-binding factors and controls pleiotropic phenotypesTransposase domestication is a recurring theme in eukaryotic genome evolution, yet it remains unresolved whether transposase-derived proteins can be co-opted to assemble multi-partner regulatory modules with phenotypic consequences. Here we show that a PIF/Harbinger-derived protein, HDP3, associates with multiple trihelix DNA-binding factors across tissues in Arabidopsis thaliana, and that these associations are modulated by abscisic acid (ABA). Genetic studies indicate that HDP3 and a representative trihelix partner act together in promoting germination and intersect with ABA signaling to influence seedling establishment, but diverge in their contributions to leaf development and flowering time. Transcriptome profiling reveals largely overlapping regulatory effects with concordant transcriptional directionality for both induced and repressed gene sets, while highlighting a notable exception at FLOWERING LOCUS C consistent with differential timing of the vegetative-to-reproductive transition. Together, these findings suggest that HDP3 supports context-dependent transcriptional outputs – likely via dynamic partnering with these trihelix factors – thereby contributing to pleiotropic developmental outcomes.2026/08/08GSE322771GSM9558146GSM9558148GSM9558147GSM955814926208322771Arabidopsis thaliana