Characterization of a Homeodomain-Leucine Zipper Gene 12: Gene Silencing in Pepper and Arabidopsis-Based Overexpression During Abiotic Stress

Homeodomain-Leucine Zipper (HD-Zip) proteins are important ubiquitous and diverse molecular chaperones in plants. We characterized a gene CaATHB-12 derived from HD-Zip I subfamily which was intensively induced by exogenous abscisic acid (ABA), salt, and mannitol applications in a pepper cultivar. Efficient gene silencing lines were created from pepper, and stable heterologous overexpression lines were created from Arabidopsis to achieve a comprehensive exploration of gene function. The functional study of CaATHB-12 in pepper increased plant sensitivity to ABA stress, while the over-expressing CaATHB-12 in Arabidopsis lines revealed that tolerance to ABA, salt, and mannitol stresses was decreased. Furthermore, CaATHB-12 plays a fundamental role in elevating the tolerance to these stresses through the increased expression of other stress related genes, increasing the activities of antioxidant enzymes and scavenging the reactive oxygen species. The studied functions of the CaATHB-12 gene may provide some insights in exquisite molecular detail by pursuing signal transduction mechanisms that converge on gene expression patterns.