Silencing GmWRKY33B genes leads to reduced disease resistance in soybean / 生物工程学报

The WRKYs are a group of plant-specific transcription factors that play important roles in defense responses. In this study, we silenced 2 GmWRKY33B homologous genes using a bean pod mosaic virus (BPMV) vector carrying a single fragment from the conserved region of the GmWRKY33B genes. Silencing GmWRKY33B did not result in morphological changes. However, significantly reduced resistances to Pseudomonas syringae pv. glycinea (Psg) and soybean mosaic virus (SMV) were observed in the GmWRKY33B-silenced plants, indicating a positive role of the GmWRKY33B genes in disease resistance. Kinase assay showed that silencing the GmWRKY33B genes significantly reduced the activation of GmMPK6, but not GmMPK3, in response to flg22 treatment. Reverse transcriptase PCR (RT-PCR) analysis of the genes encoding prenyltransferases (PTs), which are the key enzymes in the biosynthesis of glyceollin, showed that the Psg-induced expression of these genes was significantly reduced in the GmWRKY33B-silenced plants compared with the BPMV-0 empty vector plants, which correlated with the presence of the W-boxes in the promoter regions of these genes. Taken together, our results suggest that GmWRKY33Bs are involved in soybean immunity through regulating the activation of the kinase activity of GmMPK6 as well as through regulating the expression of the key genes encoding the biosynthesis of glyceollins.

Self-standing Li1.2Mn0.6Ni0.2O2/graphene membrane as a binder-free cathode for Li-ion batteries.

Lithium-rich transition-metal layered oxides (LROs), such as Li1.2Mn0.6Ni0.2O2, are promising cathode materials for application in Li-ion batteries, but the low initial coulombic efficiency, severe voltage fade and poor rate performance of the LROs restrict their commercial application. Herein, a self-standing Li1.2Mn0.6Ni0.2O2/graphene membrane was synthesized as a binder-free cathode for Li-ion batteries. Integrating the graphene membrane with Li1.2Mn0.6Ni0.2O2 forming a Li1.2Mn0.6Ni0.2O2/graphene structure significantly increases the surface areas and pore volumes of the cathode, as well as the reversibility of oxygen redox during the charge-discharge process. The initial discharge capacity of the Li1.2Mn0.6Ni0.2O2/graphene membrane is ∼270 mA h g-1 (∼240 mA h g-1 for Li1.2Mn0.6Ni0.2O2) and its initial coulombic efficiency is 90% (72% for Li1.2Mn0.6Ni0.2O2) at a current density of 40 mA g-1. The capacity retention of the Li1.2Mn0.6Ni0.2O2/graphene membrane remains at 88% at 40 mA g-1 after 80 cycles, and the rate performance is largely improved compared with that of the pristine Li1.2Mn0.6Ni0.2O2. The improved performance of the Li1.2Mn0.6Ni0.2O2/graphene membrane is ascribed to the lower charge-transfer resistance and solid electrolyte interphase resistance of the Li1.2Mn0.6Ni0.2O2/graphene membrane compared to that of Li1.2Mn0.6Ni0.2O2. Moreover, the lithium ion diffusion of the Li1.2Mn0.6Ni0.2O2/graphene membrane is enhanced by three orders of magnitude compared to that of Li1.2Mn0.6Ni0.2O2. This work may provide a new avenue to improve the electrochemical performance of LROs through tuning the oxygen redox progress during cycling.