Antagonistic Interaction between Auxin and SA Signaling Pathways Regulates Bacterial Infection through Lateral Root in Arabidopsis.

Pathogen entry into host tissues is a critical and first step in infections. In plants, the lateral roots (LRs) are a potential entry and colonization site for pathogens. Here, using a GFP-labeled pathogenic bacterium Pseudomonas syringae pv. tomato strain DC3000 (Pto DC3000), we observe that virulent Pto DC3000 invades plants through emerged LRs in Arabidopsis. Pto DC3000 strongly induced LR formation, a process that was dependent on the AUXIN RESPONSE FACTOR7 (ARF7)/ARF19-LATERAL ORGAN BOUNDARIES-DOMAIN (LBD) regulatory module. We show that salicylic acid (SA) represses LR formation, and several mutants defective in SA signaling are also involved in Pto DC3000-induced LR development. Significantly, ARF7, a well-documented positive regulator of LR development, directly represses the transcription of PR1 and PR2 to promote LR development. This study indicates that ARF7-mediated auxin signaling antagonizes with SA signaling to control bacterial infection through the regulation of LR development.

High performance Li-ion sulfur batteries enabled by intercalation chemistry.

The unstable interface of lithium metal in high energy density Li sulfur (Li-S) batteries raises concerns of poor cycling, low efficiency and safety issues, which may be addressed by using intercalation types of anode. Herein, a new prototype of Li-ion sulfur battery with high performance has been demonstrated by coupling a graphite anode with a sulfur cathode (2 mA h cm(-2)) after successfully addressing the interface issue of graphite in an ether based electrolyte.

Porous spherical carbon/sulfur nanocomposites by aerosol-assisted synthesis: the effect of pore structure and morphology on their electrochemical performance as lithium/sulfur battery cathodes.

Porous spherical carbons (PSCs) with tunable pore structure (pore volume, pore size, and surface area) were prepared by an aerosol-assisted process. PSC/sulfur composites (PSC/S, S: ca.59 wt %) were then made and characterized as cathodes in lithium/sulfur batteries. The relationships between the electrochemical performance of PSC/S composites and their pore structure and particle morphology were systematically investigated. PSC/S composite cathodes with large pore volume (>2.81 cm(3)/g) and pore size (>5.10 nm) were found to exhibit superior electrochemical performance, likely due to better mass transport in the cathode. In addition, compared with irregularly shaped carbon/sulfur composite, the spherical shaped PSC/S composite showed better performance due to better electrical contact among the particles.

Coordination chemistry in magnesium battery electrolytes: how ligands affect their performance.

Magnesium battery is potentially a safe, cost-effective, and high energy density technology for large scale energy storage. However, the development of magnesium battery has been hindered by the limited performance and the lack of fundamental understandings of electrolytes. Here, we present a study in understanding coordination chemistry of Mg(BH4)2 in ethereal solvents. The O donor denticity, i.e. ligand strength of the ethereal solvents which act as ligands to form solvated Mg complexes, plays a significant role in enhancing coulombic efficiency of the corresponding solvated Mg complex electrolytes. A new electrolyte is developed based on Mg(BH4)2, diglyme and LiBH4. The preliminary electrochemical test results show that the new electrolyte demonstrates a close to 100% coulombic efficiency, no dendrite formation, and stable cycling performance for Mg plating/stripping and Mg insertion/de-insertion in a model cathode material Mo6S8 Chevrel phase.

Controllable synthesis of α- and ß-MnO(2): cationic effect on hydrothermal crystallization.

α- and ß-MnO(2) were controllably synthesized by hydrothermally treating amorphous MnO(2) obtained via a reaction between Mn(2+) and MnO(4)(-), and cationic effects on the hydrothermal crystallization of MnO(2) were investigated systematically. The crystallization is believed to proceed by a dissolution-recrystallization mechanism; i.e. amorphous MnO(2) dissolves first under hydrothermal conditions, then condenses to recrystallize, and the polymorphs formed are significantly affected by added cations such as K(+), NH(4)(+) and H(+) in the hydrothermal systems. The experimental results showed that K(+)/NH(4)(+) were in competition with H(+) to form polymorphs of α- and ß-MnO(2), i.e., higher relative K(+)/NH(4)(+) concentration favoured α-MnO(2), while higher relative H(+) concentration favoured ß-MnO(2).