C2H2 Zinc Finger Proteins GIS2 and ZFP8 Regulate Trichome Development via Hormone Signaling in Arabidopsis.

Trichomes are specialized epidermal structures that protect plants from environmental stresses, regulated by transcription factors integrating hormonal and environmental cues. This study investigates the roles of two C2H2 zinc finger proteins, GIS2 and ZFP8, in regulating trichome patterning in Arabidopsis thaliana. Using dexamethasone-inducible overexpression lines, transcriptomic profiling, and chromatin immunoprecipitation, we identified 142 GIS2- and 138 ZFP8-associated candidate genes involved in sterol metabolism, senescence, and stress responses. GIS2 positively and directly regulated the expression of SQE5, linked to sterol biosynthesis and drought tolerance, and repressed SEN1, a senescence marker associated with abscisic acid and phosphate signaling. ZFP8 modulated stress-related target genes, including PR-4 and SPL15, with partial functional overlap between GIS family members. Spatially, GIS2 functions in inflorescence trichomes via integrating gibberellin-cytokinin pathways, while ZFP8 influences leaf trichomes through cytokinin and abscisic acid signal. Gibberellin treatment stabilized GIS2 protein and induced SQE5 expression, whereas SEN1 repression was gibberellin-independent. Chromatin immunoprecipitation and DEX-CHX experiment confirmed GIS2 binding to SQE5 and SEN1 promoters at conserved C2H2 motifs. These findings highlight hormone-mediated transcriptional regulation of trichome development by GIS2 and ZFP8, offering mechanistic insight into signal integration. The results provide a foundation for future crop improvement strategies targeting trichome-associated stress resilience.