The Molecular Mechanisms Of Zinc Finger Protein Genes ZFP5、ZFP6and GIS3Control Epidermal Cell Development By Integrating Plant Hormone Signalings In Arabidopsis

Arabidopsis (Arabidopsis thaliana) trichome and root hair development is an excellent model system for studying cell development, cell differentiation and cell cycle. Our previous studies have shown that GLABROUS INFLORESCENCE STEMS (GIS) family genes, GIS, GLABROUS INFLORESCENCE STEMS2(GIS2) and ZINC FINGER PROTEIN8(ZFP8), control shoot maturation and epidermal cell fate by integrating gibberellins (GAs) and cytokinin signaling in Arabidopsis. Here, we show that three new C2H2zinc finger proteins, ZINC FINGER PROTEIN5(ZFP5), ZINC FINGER PROTEIN6(ZFP6), GLABROUS INFLORESCENCE STEMS3(GIS3) play important roles in controlling root hair and trichome cell development through cytokinin and GA signalings.1. Overexpression of ZFP5resulted in significantly more trichomes on carpels and other inflorescence organs than wild-type plants. zfp5loss-of-function mutant and RNAi lines exhibited reduced numbers of trichomes on sepals, cauline leaves, paraclades and main inflorescence stems in comparison to wild-type plants. Moreover, loss of ZFP5function resulted in shorter and fewer root hairs. More importantly, ZFP5mediated the regulation of trichome initiation by gibberellins. ZFP5gene expression was regulated by different plant hormones and nutrients. The molecular analyses suggested that ZFP5functions upstream of GIS, GIS2, ZFP8, and the key trichome initiation regulators GLABROUS1(GL1) and GLABROUS3(GL3). We further demonstrated that ZFP8was the direct target of ZFP5in controlling trichome cell differentiation, and CPC was the direct target of ZFP5in controlling root hair cell differentiation by using a steroid-inducible activation of ZFP5and ChIP experiment.2. Overexpression of ZFP6led to significantly more trichomes on carpels and other inflorescence organs than the control plants. zfp6loss-of-function mutants resulted in fewer trichomes on sepals and lateral branch in comparison to wild-type plants. Moreover, loss of ZFP6function resulted in shorter and less root hairs than their wild type control. ZFP6mediated the regulation of trichome initiation by gibberellins and regulated the development of root hair by cytokinins. The molecular analyses suggested that ZFP6functions upstream of ZFP5, GIS, GIS2, ZFP8, and the key trichome initiation regulators GLABROUS I (GLI) and GLABROUS3(GL3). 3. Overexpression of GIS3resulted in significantly more trichomes on carpels and other inflorescence organs than the control plants. gis3loss-of-function mutants showed a reduced number of trichomes on sepals, and paraclades in comparison to wild-type plants. It was found that GIS3also mediates the regulation of trichome initiation by gibberellins. The molecular analyses demonstrated that GIS3functioned upstream of ZFP6, ZFP5, GIS, GIS2. ZFP8, the key trichome initiation regulators GLABROUS1(GL1) and GLABROUS3(GL3).In summary, ZFP5、ZFP6and GIS3are major genes controlling the development of trichomes and root hairs. This study further supports that GIS family genes control the initiation and development of trichomes and root hairs by integrating hormonal signaling.