Tomato SlPUB24 enhances resistance to Xanthomonas euvesicatoria pv. perforans race T3

Solanum lycopersicum var.cerasiforme accession PI 114490 has broad-spectrum resistance to bacterial spot caused by several species of Xanthomonas.Resistance is quantitatively inherited,and a common quantitative trait locus QTL-11B on chromosome 11 has been identified previously.In this study,the SlPub24 gene was characterized in QTL-11B.SlPub24 in PI 114490 was upregulated by infection with X.euvesicatoria pv.perforans race T3,but its transcription was low in the susceptible line OH 88119 whether or not it was infected by the pathogen.The differential expression of SlPub24 between PI 114490 and OH 88119 was due to great sequence variation in the promoter region.The promoter of SlPub24 in OH 88119 had very low activity and did not respond to pathogen infection.Transgenic lines of OH 88119 overexpressing SlPub24 isolated from PI 114490 showed significantly enhanced resistance,while mutants of Slpub24 generated by CRISPR/Cas9 editing showed more susceptibility to race T3 and to other races.The mutants also showed spontaneous cell death in leaves.The expression of the salicylic acid(SA)pathway gene phenylalanine ammonia-lyase(PAL)and signaling-related genes pathogenesis-related(PR1)and nonexpresser of PR1(NPR1)were influenced by SlPub24.The content of SA in tomato plants was consistent with the level of SlPub24 expression.Furthermore,SlPUB24 interacted with the cell wall protein SlCWP and could regulate the degradation of SlCWP.The expression levels of SlCWP and SlCWINV1,a cell wall invertase gene,showed opposite patterns during pathogen infection.The activity of SlCWINV1 was lower in mutants than in PI 114490.The results are discussed in terms of the roles of the abovementioned genes,and a potential model for SlPUB24-mediated resistance to bacterial spot is proposed.

草原健康、退化与恢复一体化评估:概念与方法

草原是我国面积最大的陆地生态系统,具有重要的水库、钱库、粮库、碳库功能,在生物多样性保护、气候和水的调节以及全球生物地球化学循环中发挥着关键作用,为人类提供了广泛的物质和非物质利益,特别是食物生产、水供应和调节、碳储存和气候减缓、授粉和文化服务[1~3].

Maghemite(γ-Fe_2O_3) nanoparticles enhance dissimilatory ferrihydrite reduction by Geobacter sulfurreducens: Impacts on iron mineralogical change and bacterial interactions

Microbially mediated bioreduction of iron oxyhydroxide plays an important role in the biogeochemical cycle of iron.Geobacter sulfurreducens is a representative dissimilatory ironreducing bacterium that assembles electrically conductive pili and cytochromes.The impact of supplementation withγ-Fe_2O_3 nanoparticles(NPs)(0.2 and 0.6 g)on the G.sulfurreducens-mediated reduction of ferrihydrite was investigated.In the overall performance of microbial ferrihydrite reduction mediated byγ-Fe_2O_3 NPs,stronger reduction was observed in the presence of direct contact withγ-Fe_2O_3 NPs than with indirect contact.Compared to the production of Fe(Ⅱ)derived from biotic modification with ferrihydrite alone,increases greater than 1.6-and 1.4-fold in the production of Fe(Ⅱ)were detected in the biotic modifications in which direct contact with 0.2 g and 0.6 gγ-Fe_2O_3 NPs,respectively,occurred.X-ray diffraction analysis indicated that magnetite was a unique representative iron mineral in ferrihydrite when active G.sulfurreducens cells were in direct contact withγ-Fe_2O_3 NPs.Because of the sorption of biogenic Fe(Ⅱ)ontoγ-Fe_2O_3 NPs instead of ferrihydrite,the addition ofγ-Fe_2O_3 NPs could also contribute to increased duration of ferrihydrite reduction by preventing ferrihydrite surface passivation.Additionally,electron microscopy analysis confirmed that the direct addition ofγ-Fe_2O_3 NPs stimulated the electrically conductive pili and cytochromes to stretch,facilitating long-range electron transfer between the cells and ferrihydrite.The obtained findings provide a more comprehensive understanding of the effects of iron oxide NPs on soil biogeochemistry.

Nano-sized Fe_2O_3/Fe_3O_4 facilitate anaerobic transformation of hexavalent chromium in soil–water systems

The purpose of this study is to investigate the effects of nano-sized or submicro Fe_2O_3/Fe_3O_4 on the bioreduction of hexavalent chromium（Cr（VI）） and to evaluate the effects of nano-sized Fe_2O_3/Fe_3O_4 on the microbial communities from the anaerobic flooding soil.The results indicated that the net decreases upon Cr（VI） concentration from biotic soil samples amended with nano-sized Fe_2O_3（317.1 ± 2.1 mg/L） and Fe_3O_4（324.0 ± 22.2 mg/L） within21 days,which were approximately 2-fold of Cr（VI） concentration released from blank control assays（117.1 ± 5.6 mg/L）.Furthermore,the results of denaturing gradient gel electrophoresis（DGGE） and high-throughput sequencing indicated a greater variety of microbes within the microbial community in amendments with nano-sized Fe_2O_3/Fe_3O_4 than the control assays.Especially,Proteobacteria occupied a predominant status on the phylum level within the indigenous microbial communities from chromium-contaminated soils.Besides,some partial decrease of soluble Cr（VI） in abiotic nano-sized Fe_2O_3/Fe_3O_4 amendments was responsible for the adsorption of nano-sized Fe_2O_3/Fe_3O_4 to soluble Cr（VI）.Hence,the presence of nano-sized Fe_2O_3/Fe_3O_4 could largely facilitate the mobilization and biotransformation of Cr（VI） from flooding soils by adsorption and bio-mediated processes.