Three-Dimensional N-Doped Carbon Nanotube/Graphene Composite Aerogel Anode to Develop High-Power Microbial Fuel Cell

Optimizing the structure of electrode materials is one of the most effective strategies for designing high-power microbial fuel cells(MFCs).However,electrode materials currently suffer from a series of shortcomings that limit the output of MFCs,such as high intrinsic resistance,poor electrolyte wettability,and low microbial load capacity.Here,a three-dimensional(3D)nitrogen-doped multiwalled carbon nanotube/graphene(N-MWCNT/GA)composite aerogel is synthesized as the anode for MFCs.Comparing nitrogen-doped GA,MWCNT/GA,and N-MWCNT/GA,the macroporous hydrophilic N-MWCNT/GA electrode with an average pore size of 4.24μm enables high-density loading of the microbes and facilitates extracellular electron transfer with low intrinsic resistance.Consequently,the hydrophilic surface of N-MWCNT can generate high charge mobility,enabling a high-power output performance of the MFC.In consequence,the MFC system based on N-MWCNT/GA anode exhibits a peak power density and output voltage of 2977.8 mW m^(−2)and 0.654 V,which are 1.83 times and 16.3%higher than those obtained with MWCNT/GA,respectively.These results demonstrate that 3D N-MWCNT/GA anodes can be developed for high-power MFCs in different environments by optimizing their chemical and microstructures.

Woody plant cell walls:Fundamentals and utilization

Cell walls in plants,particularly forest trees,are the major carbon sink of the terrestrial ecosystem.Chemical and biosynthetic features of plant cell walls were revealed early on,focusing mostly on herbaceous model species.Recent developments in genomics,transcriptomics,epigenomics,transgenesis,and associated analytical techniques are enabling novel insights into formation of woody cell walls.Here,we review multilevel regulation of cell wall biosynthesis in forest tree species.We highlight current approaches to engineering cell walls as potential feedstock for materials and energy and survey reported field tests of such engineered transgenic trees.We outline opportunities and challenges in future research to better understand cell type biogenesis for more efficient wood cell wall modification and utilization for biomaterials or for enhanced carbon capture and storage.

饲草作物基础生物学与生物育种

饲草作物在保障国家大粮食安全的重要性日渐突出,饲草产业的健康发展迫切需要系统布局饲草作物基础生物学研究和生物育种科技战略。本文综述了主要饲草作物的种类和生物学特性、基因组学和主要性状功能基因研究进展,分析了以设计“理想饲草”为目标的饲草生物育种需要深度解析饲草特化生物学性状形成的分子基础,饲草驯化性状的分子调控,并借鉴粮食作物驯化研究的前沿进展实现饲草作物的从头快速驯化。建议发挥我国在饲草基因组学和基因编辑等方面的领先优势,大力发展大数据、人工智能驱动的新技术和新理论,引领饲草作物基础生物学与生物育种领域的突破。

Systematic Full-Cycle Engineering Microbial Biofilms to Boost Electricity Production in Shewanella oneidensis

Electroactive biofilm plays a crucial rule in the electron transfer efficiency of microbial electrochemical systems(MES).However,the low ability to form biofilm and the low conductivity of the formed biofilm substantially limit the extracellular electron transfer rate of microbial cells to the electrode surfaces in MES.

The RLCK-VND6 module coordinates secondary cell wall formation and adaptive growth in rice

The orderly deposition of secondary cell wall(SCW)in plants is implicated in various biological programs and is precisely controlled.Although many positive and negative regulators of SCW have been documented,the molecular mechanisms underlying SCW formation coordinated with distinct cellular physiological processes during plant adaptive growth remain largely unclear.Here,we report the identification of Cellulose Synthase co-expressed Kinase1(CSK1),which encodes a receptor-like cytoplasmic kinase,as a negative regulator of SCW formation and its signaling cascade in rice.Transcriptome deep sequencing of developing internodes and genome-wide co-expression assays revealed that CSK1 is co-expressed with cellulose synthase genes and is responsive to various stress stimuli.The increased SCW thickness and vigorous vessel transport in csk1 indicate that CSK1 functions as a negative regulator of SCW biosynthesis.Through observation of green fluorescent protein-tagged CSK1 in rice protoplasts and stable transgenic plants,we found that CSK1 is localized in the nucleus and cytoplasm adjacent to the plasma membrane.Biochemical and molecular assays demonstrated that CSK1 phosphorylates VASCULAR-RELATED NAC-DOMAIN 6(VND6),a master SCW-associated transcription factor,in the nucleus,which reduces the transcription of a suite of SCW-related genes,thereby attenuating SCW accumulation.Consistently,genetic analyses show that CSK1 functions upstream of VND6 in regulating SCW formation.Interestingly,our physiological analyses revealed that CSK1 and VND6 are involved in abscisic acid-mediated regulation of cell growth and SCW deposition.Taken together,these results indicate that the CSK1-VND6 module is an important component of the SCW biosynthesis machinery,which coordinates SCW accumulation and adaptive growth in rice.Our study not only identifies a new regulator of SCW biosynthesis but also reveals a fine-tuned mechanism for precise control of SCW deposition,offering tools for rationally tailoring agronomic traits.

强化产电微生物与电极间电子传递速率的研究进展

产电微生物是微生物燃料电池、电解池和电合成等微生物电化学技术(Microbial electrochemical technologies,METs)的研究基础。产电微生物与电极界面间的胞外电子传递(Extracellular electron transfer,EET)效率低以及生物被膜形成能力弱限制了METs在有机物降解、电能生产、海水淡化、生物修复和生物传感等方面的应用。因此,强化产电微生物与电极界面间的相互作用是过去几年的主要研究热点。针对近年的研究,本文系统概述了通过改造产电微生物来增强微生物-电极间相互作用的各种策略,重点分析了这些策略的适用性和局限性,并展望了强化产电微生物-电极界面作用在微生物电化学技术利用方面的研究前景。

产电微生物的筛选方法研究进展

产电微生物是一类具有胞外电子转移能力的微生物,能够将有机物中储存的化学能转化为电能,其作为微生物电催化系统的催化剂,已经成为环境和能源领域的研究热点。但目前所发现的产电菌,产电机制有所差异,产电能力参差不齐,菌株的性能从根本上影响了其产电能力,其产电能力不足成为限制微生物燃料电池在工业上广泛应用的主要瓶颈。目前,通过理性设计或定向进化等改造方法,难以实现产电微生物在复杂多样环境中的广泛应用。通过定向筛选策略,建立一套快速、高效的筛选鉴定技术,挖掘环境中性能优异的产电微生物,是促进其广泛应用的有效途径。文中基于产电微生物的种类,总结回顾了现有的产电微生物的筛选鉴定方法,并对其研究前景进行了展望。

An Uncanonical CCCH-Tandem Zinc-Finger Protein Represses Secondary Wall Synthesis and Controls Mechanical Strength in Rice

Secondary walls, which represent the bulk of biomass, have a large impact on plant growth and adaptation to environments. Secondary wall synthesis is switched and regulated by a sophisticated signaling transduction network. However, there is limited understanding of these regulatory pathways. Here, we report that ILAl-interacting protein 4 （lIP4） can repress secondary wall synthesis, lIP4 is a phosphorylation sub- strate of an Raf-like MAPKKK, but its function is unknown. By generating lip4 mutants and relevant transgenic plants, we found that lesions in lIP4 enhance secondary wall formation. Gene expression and transactivation activity assays revealed that lIP4 negatively regulates the expression of MYB61 and CESAs but does not bind their promoters, lIP4 interacts with NAC29/NAC31, the upstream regulators of secondary wall synthesis, and suppresses the downstream regulatory pathways in plants. Mutagenesis analyses showed that phosphomimic UP4 proteins translocate from the nucleus to the cytoplasm, which releases interacting NACs and attenuates its repression function. Moreover, we revealed that liPs are evolutionarily conserved and share unreported CCCH motifs, referred to as uncanonical CCCH-tandem zinc-finger proteins. Collectively, our study provides mechanistic insights into the control of secondary wall synthesis and presents an opportunity for improving relevant agronomic traits in crops.

The plant cell wall: Biosynthesis, construction, and functions

The plant cell wall is composed of multiple biopolymers, representing one of the most complex structural networks in nature. Hundreds of genes are involved in building such a natural masterpiece. However, the plant cell wall is the least understood cellular structure in plants. Due to great progress in plant functional genomics,manyachievementshavebeenmadein uncovering cell wall biosynthesis, assembly, and architecture, as well as cell wall regulation and signaling. Such information has significantly advanced our understanding of the roles of the cell wall in many biological and physiological processes and has enhanced our utilization of cell wall materials. The use of cutting-edge technologies such as single-molecule imaging,nuclear magnetic resonance spectroscopy, and atomic force microscopy has provided much insight into the plant cell wall as an intricate nanoscale network, opening up unprecedented possibilities for cell wall research. In this review,we summarize the major advances made in understanding the cell wall in this era of functional genomics, including the latest findings on the biosynthesis, construction, and functions of the cell wall.

Constructing a high-density linkage map for Gossypium hirsutum × Gossypium barbadense and identifying QTLs for lint percentage

To introgress the good fiber quality and yield from Gossypium barbadense into a commercial Upland cotton variety, a high‐density simple sequence repeat （SSR） genetic linkage map was developed from a BC1F1 population of Gossypium hirsutum × Gossypium barbadense. The map com-prised 2,292 loci and covered 5115.16 centiMorgan （cM） of the cotton AD genome, with an average marker interval of 2.23 cM. Of the marker order for 1,577 common loci on this new map, 90.36% agrees well with the marker order on the D genome sequence genetic map. Compared with five pub-lished high‐density SSR genetic maps, 53.14% of marker loci were newly discovered in this map. Twenty‐six quantitative trait loci （QTLs） for lint percentage （LP） were identified on nine chromosomes. Nine stable or common QTLs could be used for marker‐assisted selection. Fifty percent of the QTLs were from G. barbadense and increased LP by 1.07%–2.41%. These results indicated that the map could be used for screening chromosome substitution segments from G. barbadense in the Upland cotton background, identifying QTLs or genes from G. barbadense, and further developing the gene pyramiding effect for improving fiber yield and quality.

Phenylpropanoid Derivatives Are Essential Components of Sporopollenin in Vascular Plants

The outer wall of pollen and spores,namely the exine,is composed of sporopollenin,which is highly resistant to chemical reagents and enzymes.In this study,we demonstrated that phenylpropanoid pathway derivatives are essential components of sporopollenin in seed plants.Spectral analyses showed that the autofluorescence of Lilium and Arabidopsis sporopollenin is similar to that of lignin.Thioacidolysis and NMR analyses of pollen from Lilium and Cryptomeria further revealed that the sporopollenin of seed plants contains phenylpropanoid derivatives,including p-hydroxybenzoate(p-BA),p-coumarate(p-CA),ferulate(FA),and lignin guaiacyl(G)units.The phenylpropanoid pathway is expressed in the tapetum in Arabidopsis,consistent with the fact that the sporopollenin precursor originates from the tapetum.Further germination and comet assays showed that this pathway plays an important role in protection of pollen against UV radiation.In the pteridophyte plant species Ophioglossum vulgatum and Lycopodium clavata,phenylpropanoid derivatives including p-BA and p-CA were also detected,but G units were not.Taken together,our results indicate that phenylpropanoid derivatives are essential for sporopollenin synthesis in vascular plants.In addition,sporopollenin autofluorescence spectra of bryophytes,such as Physcomitrella and Haplocladium,exhibit distinct characteristics compared with those of vascular plants,indicating the diversity of sporopollenin among land plants.

Engineering Shewanella carassii, a newly isolated exoelectrogen from activated sludge, to enhance methyl orange degradation and bioelectricity harvest

Electroactive microorganisms(EAMs)play important roles in biogeochemical redox processes and have been of great interest in the fields of energy recovery,waste treatment,and environmental remediation.However,the currently identified EAMs are difficult to be widely used in complex and diverse environments,due to the existence of poor electron transfer capability,weak environmental adaptability,and difficulty with engineering modifications,etc.Therefore,rapid and efficient screening of high performance EAMs from environments is an effective strategy to facilitate applications of microbial fuel cells(MFCs).In this study,to achieve efficient degradation of methyl orange(MO)by MFC and electricity harvest,a more efficient exoelectrogen Shewanella carassii-D5 that belongs to Shewanella spp.was first isolated from activated sludge by WO_(3) nanocluster probe technique.Physiological properties experiments confirmed that S.carassii-D5 is a Gram-negative strain with rounded colonies and smooth,slightly reddish surface,which could survive in media containing lactate at 30℃.Moreover,we found that S.carassii-D5 exhibited remarkable MO degradation ability,which could degrade 66%of MO within 72 h,1.7 times higher than that of Shewanella oneidensis MR-1.Electrochemical measurements showed that MFCs inoculated with S.carassii-D5 could generate a maximum power density of 704.6 mW/m^(2),which was 5.6 times higher than that of S.oneidensis MR-1.Further investigation of the extracellular electron transfer(EET)mechanism found that S.carassii-D5 strain had high level of c-type cytochromes and strong biofilm formation ability compared with S.oneidensis MR-1,thus facilitating direct EET.Therefore,to enhance indirect electron transfer and MO degradation capacity,a synthetic gene cluster ribADEHC encoding riboflavin synthesis pathway from Bacillus subtilis was heterologously expressed in S.carassii-D5,increasing riboflavin yield from 1.9 to 9.0 mg/g DCW with 1286.3 mW/m^(2) power density output in lactate fed-MFCs.Furthermore,results showed that the high EET rate endowed a faster degradation efficient of MO from 66%to 86%with a maximum power density of 192.3 mW/m^(2),which was 1.3 and 1.6 times higher than that of S.carassii-D5,respectively.Our research suggests that screening and engineering high-efficient EAMs from sludge is a feasible strategy in treating organic pollutants.

Rab-H_1b is essential for trafficking of cellulose synthase and for hypocotyl growth in Arabidopsis thaliana

Ceil-wall deposition of cellulose microfibrils is essential for plant growth and development. In plant cells, cellulose synthesis is accomplished by cellulose synthase complexes located in the plasma membrane. Trafficking of the complex between endomembrane compartments and the plasma membrane is vital for cellulose biosynthesis; however, the mechanism for this process is not well understood. We here report that, in Arabidopsis thaliana, Rab-H1b, a Golgi-localized small GTPase, participates in the trafficking of CELLULOSE SYNTHASE 6 （CESA6） to the plasma membrane. Loss of Rab-Hlb function resulted in altered distribution and motility of CESA6 in the plasma membrane and reduced cellulose content. Seedlings with this defect exhibited short, fragile etiolated hypocotyls.Exocytosis of CESA6 was impaired in rab-Mb cells, and endocytosis in mutant cells was significantly reduced as well. We further observed accumulation of vesicles around an abnormal Golgi apparatus having an increased number of cisternae in rab-Mb cells, suggesting a defect in cisternal homeostasis caused by Rab-Hlb loss function. Our findings link Rab GTPases to cellulose biosynthesis, during hypo- cotyl growth, and suggest Rab-Hlb is crucial for modulating the trafficking of cellulose synthase complexes between endomembrane compartments and the plasma membrane and for maintaining Golgi organization and morphology.

A solid-state nanopore-based single-molecule approach for label-free characterization of plant polysaccharides

Polysaccharides are important biomacromolecules existing in all plants,most of which are integrated into a fibrillar structure called the cell wall.In the absence of an effective methodology for polysaccharide analysis that arises from compositional heterogeneity and structural flexibility,our knowledge of cell wall architecture and function is greatly constrained.Here,we develop a single-molecule approach for identifying plant polysaccharides with acetylated modification levels.We designed a solid-state nanopore sensor supported by a free-standing SiNx membrane in fluidic cells.This device was able to detect cell wall polysaccharide xylans at concentrations as low as 5 ng/mL and discriminate xylans with hyperacetylated and unacetylated modifications.We further demonstrated the capability of this method in distinguishing arabinoxylan and glucuronoxylan in monocot and dicot plants.Combining the data for categorizing polysaccharide mixtures,our study establishes a single-molecule platformfor polysaccharide analysis,opening a new avenue for understanding cell wall structures,and expanding polysaccharide applications.

Engineering Shewanella-re duce d graphene oxide aerogel biohybrid to efficiently synthesize Au nanoparticles

Biosynthesizing Au nanoparticles(AuNPs)from gold-bearing scraps provides a sustainable method to meet the urgent demand for AuNPs.However,it remains challenging to efficiently biosynthesize AuNPs of which the diameter is less than 10 nm from a trace amount of Au^(3+)concentration at the level of tens ppm.Here,we constructed an exoelectrogenic cell(eCell)-conductive reduced-graphene-oxide aero-gel(rGA)biohybrid by assembling Shewanella sp.S1(SS1)as living biocatalyst and rGA as conductive ad-sorbent,in which Au^(3+)at trace concentrations would be enriched by the adsorption of rGA and reduced to AuNPs through the extracellular electron transfer(EET)of SS1.To regulate the size of the synthe-sized AuNPs to 10 nm,the strain SS1 was engineered to enhance its EET,resulting in strain RS2(pYYD-P tac-ribADEHC&pHG13-P_(bad)-omcC in SS1).Strain RS2 was further assembled with rGA to construct the RS2-rGA biohybrid,which could synthesize AuNPs with the size of 7.62±2.82 nm from 60 ppm Au^(3+)so-lution.The eCell-rGA biohybrid integrated Au^(3+)adsorption and reduction,which enabled AuNPs biosyn-thesis from a trace amount of Au^(3+).Thus,the required Au^(3+)ions concentration was reduced by one or two orders of magnitude compared with conventional methods of AuNPs biosynthesis.Our work devel-oped an AuNPs size regulation technology via engineering eCell’s EET with synthetic biology methods,providing a feasible approach to synthesize AuNPs with controllable size from trace level of gold ions.