Transcriptome analysis reveals dynamic changes in the salt stress response in Salix

Soil salinization is a serious ecological problem worldwide and information regarding the salt tolerance mechanisms of Salix is scarce.To elucidate the dynamic changes in the molecular mechanisms of Salix under salt stress,we generated gene expression profiles and examined changes in the expression of those genes.RNA-Seq was used to produce six cDNA libraries constructed from the leaves of Salix ×jiangsuensis CL‘J2345’treated with NaCl for 0,2,6,12,24 and 48 h.In total,249 million clean reads were assembled into 12,739 unigenes,all of which were clustered into 10 profiles based on their temporal expression patterns.KEGG analysis revealed that as an early defense response,the biosynthesis pathways of cutin,suberin and wax,which are involved in cell wall structure,were activated beginning at 2 h.The expression of secondary metabolism genes,including those involved in the phenylpropanoid,flavonoid,stilbenoid,diarylheptanoid and gingerol pathways,peaked at 6 h and 24 h;the upregulated genes were mainly involved in plant hormone pathways and beta-alanine,galactose and betalain metabolism.We identified roles of key phytohormones and found ETH to be the major signaling molecule activating TFs at 12 h;ETH,ABA,IAA and SA were the key molecules at 24 h.Moreover,we found that the upregulated genes were associated with elevated levels of amino acids,sucrose,inositol,stress proteins and ROS-scavenging enzymes,contributing to the maintenance of water balance.This research constitutes the first detailed analysis of salt stress-related mechanisms in Salix and identifies potential targets for genetic manipulation to improve yields.

Fabrication and Dealloying Behavior of Monolithic Nanoporous Copper Ribbons with Bimodal Channel Size Distributions

Monolithic nanoporous copper （NPC） ribbons with bimodal channel size distributions can be fabricated through chemical dealloying of Mg-32 Cu alloy in an acidic solution at room temperature. The microstructure of the as- dealloyed samples was characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis. These NPC ribbons are composed of interconnected large-sized channels （hundreds of nm） with highly porous channel walls （tens of nm）. Both large- and small-sized channels are open, bicontinuous, and interpenetrating. Additionally, it is the first time to find that the evolution process of porous structure along the thickness direction of samples during the dealloying is from the interior to exterior, which is just contrary to the coarsening process along the thickness direction during the post-dealloying. Meanwhile, the corresponding mechanism is discussed in detail.