Phosphate (Pi) stress-responsive transcription factors PdeWRKY6 and PdeWRKY65 regulate the expression of PdePHT1;9 to modulate tissue Pi concentration in poplar.

Phosphorus (P) is an important nutrient for plants. Here, we identify a WRKY transcription factor (TF) in poplar (Populus deltoides × Populus euramericana) (PdeWRKY65) that modulates tissue phosphate (Pi) concentrations in poplar. PdeWRKY65 overexpression (OE) transgenic lines showed reduced shoot Pi concentrations under both low and normal Pi availabilities, while PdeWRKY65 reduced expression (RE) lines showed the opposite phenotype. A gene encoding a Pi transporter (PHT), PdePHT1;9, was identified as the direct downstream target of PdeWRKY65 by RNA sequencing (RNA-Seq). The negative regulation of PdePHT1;9 expression by PdeWRKY65 was confirmed by DNA-protein interaction assays, including yeast one-hybrid (Y1H), electrophoretic mobility shift assay (EMSA), co-expression of the promoters of PdePHT1;9 and PdeWRKY65 in tobacco (Nicotiana benthamiana) leaves, and chromatin immunoprecipitation-quantitative PCR. A second WRKY TF, PdeWRKY6, was subsequently identified and confirmed to positively regulate the expression of PdePHT1;9 by DNA-protein interaction assays. PdePHT1;9 and PdeWRKY6 OE and RE poplar transgenic lines were used to confirm their positive regulation of shoot Pi concentrations, under both normal and low Pi availabilities. No interaction between PdeWRKY6 and PdeWRKY65 was observed at the DNA or protein levels. Collectively, these data suggest that the low Pi-responsive TFs PdeWRKY6 and PdeWRKY65 independently regulate the expression of PHT1;9 to modulate tissue Pi concentrations in poplar.

Exploration of the Hepatoprotective Effect and Mechanism of Swertia mussotii Franch in an Acute Liver Injury Rat Model.

BACKGROUND AND OBJECTIVE: Swertia mussotii Franch, also known as "Zangyinchen", is one of a Tibetan traditional herb used for treatment of liver diseases over thousands of years at Qinghai-Tibet Plateau, has been confirmed to be hepatoprotective. However, the underlying mechanism is largely unknown. MATERIALS AND METHODS: In this study, we evaluated the effect of S. mussotii treatment in a carbon tetrachloride-induced acute liver injury rat model by examining the serum alanine aminotransferase, aspartate aminotransferase, total bilirubin levels and performing histological observations of the liver tissues. Meanwhile, the metabolomics analysis was used to explore the molecular mechanism of S. mussotii treatment by high performance liquid chromatography tandem mass spectrometry. RESULTS: The results showed that S. mussotii treatment could effectively improve the serum alanine aminotransferase, aspartate aminotransferase, total bilirubin in acute liver injury rat model. Histological observation showed that S. mussotii treatment could effectively alleviate liver injury. Moreover, the metabolomics analysis showed that S. mussotii treatment could normalize the levels of many fatty acid metabolism related metabolites. And the results of pathway analysis showed that these metabolites significantly enriched in fatty acid biosynthesis pathway (myristic acid, dodecanoic acid and capric acid) and linoleic acid metabolism pathway (13-OxoODE). CONCLUSION: The results indicated that S. mussotii treatment could significantly improve acute liver injury through affecting the pathways related to lipid metabolism.