A Cys2His2 Zinc Finger Transcription Factor Positively Modulates Salt Stress in .

Zinc finger proteins (ZFPs) are widely involved in plant growth and abiotic stress responses, however, few of these proteins have been functionally characterized in tree species. In this study, we cloned and characterized the gene encoding a C2H2-type ZFP from . is a transcription factor localized in the nucleus, with a transcription activation domain located at the N-terminus. was predominantly expressed in stems and was induced by salt. We generated transgenic birch lines displaying overexpression (OE) or RNAi silencing (Ri) of and exposed these along with wild-type birch seedlings to salinity. Phenotypic and physiological parameters such as superoxide dismutase, peroxisome, HO content, proline content, water loss rate, and malondialdehyde content were examined. Overexpression of in birch conferred increased salt tolerance. Chromatin immunoprecipitation-qPCR and RNA-seq showed that BpSZA1 binds to the GAGA-motif in the promoter of downstream target genes including , , , and to activate their transcription. also participates in abscisic acid (ABA) biosynthesis, proline biosynthesis, and the ABA/jasmonic acid pathway to enhance the salt stress of .