Lignin is an integral part of secondary cell walls in plants and plays important roles in maintaining the strength of stems, enhancing transport ability of stems, and providing resistance to multiple stresses. Lignin biosynthesis has become one of the hotspots in molecular forest biology research. The AP1 transcription factor plays important roles in plant flower development. However, in this study, suppression of BpAP1 altered the transcription profiles of white birch and RNA-seq was used to find that suppression of BpAP1 changed the expression of lignin pathway-related genes; C4H/CYP73A, POD were down-regulated and HCT, CCoAOMT, REF1 and CAD were up-regulated. Cell walls of the suppressed transgenic birch were significantly thinner than the wild type of birch, and BpAP1- repressed birch contained less lignin. In addition to regulation of floral development, BpAP1 might play a role in regulating the expression of genes in lignin biosynthesis of birch. This study could provide a new insight into the function of AP1 genes in woody species.

Trehalose is a non-reducing disaccharide with high stability and strong water absorption properties that can improve the resistance of organisms to various abiotic stresses. Trehalose-6-phosphate synthase (TPS) plays important roles in trehalose metabolism and signaling. In this study, the full-length cDNA of ThTPS was cloned from Tamarix hispida Willd. A phylogenetic tree including ThTPS and 11 AtTPS genes from Arabidopsis indicated that the ThTPS protein had a close evolutionary relationship with AtTPS7. However, the function of AtTPS7 has not been determined. To analyze the abiotic stress tolerance function of ThTPS, the expression of ThTPS in T. hispida under salt and drought stress and JA, ABA and GA3 hormone stimulation was monitored by qRT-PCR. The results show that ThTPS expression was clearly induced by all five of these treatments at one or more times, and salt stress caused particularly strong induction of ThTPS in the roots of T. hispida. The ThTPS gene was transiently overexpressed in T. hispida. Both physiological indexes and staining results showed that ThTPS gene overexpression increased salt and osmotic stress tolerance in T. hispida. Overall, the ThTPS gene can respond to abiotic stresses such as salt and drought, and its overexpression can significantly improve salt and osmotic tolerance. These findings establish a foundation to better understand the responses of TPS genes to abiotic stress in plants.