The genome of Medicago polymorpha provides insights into its edibility and nutritional value as a vegetable and forage legume

Medicago polymorpha is a nutritious and palatable forage and vegetable plant that also fixes nitrogen.Here,we reveal the chromosome-scale genome sequence of M.polymorpha using an integrated approach including Illumina,PacBio and Hi-C technologies.We combined PacBio full-length RNA-seq,metabolomic analysis,structural anatomy analysis and related physiological indexes to elucidate the important agronomic traits of M.polymorpha for forage and vegetable usage.The assembled M.polymorpha genome consisted of 457.53Mb with a long scaffold N50 of 57.72Mb,and 92.92%(441.83Mb)of the assembly was assigned to seven pseudochromosomes.Comparative genomic analysis revealed that expansion and contraction of the photosynthesis and lignin biosynthetic gene families,respectively,led to enhancement of nutritious compounds and reduced lignin biosynthesis in M.polymorpha.In addition,we found that several positively selected nitrogen metabolism-related genes were responsible for crude protein biosynthesis.Notably,the metabolomic results revealed that a large number of flavonoids,vitamins,alkaloids,and terpenoids were enriched in M.polymorpha.These results imply that the decreased lignin content but relatively high nutrient content of M.polymorpha enhance its edibility and nutritional value as a forage and vegetable.Our genomic data provide a genetic basis that will accelerate functional genomic and breeding research on M.polymorpha as well as other Medicago and legume plants.

Techniques for detecting protein-protein interactions in living cells:principles, limitations, and recent progress

Detecting protein-protein interactions(PPIs) provides fundamental information for understanding biochemical processes such as the transduction of signals from one cellular location to another; however, traditional biochemical techniques cannot provide sufficient spatio-temporal information to elucidate these molecular interactions in living cells. Over the past decade, several new techniques have enabled the identification and characterization of PPIs. In this review, we summarize three main techniques for detecting PPIs in vivo, focusing on their basic principles and applications in biological studies. We place a special emphasis on their advantages and limitations, and, in particular, we introduced some uncommon new techniques, such as single-molecule FRET(smFRET), FRET-fluorescence lifetime imaging microscopy(FRET-FLIM), cytoskeleton-based assay for protein-protein interaction(CAPPI) and single-molecule protein proximity index(smPPI), highlighting recent improvements to the established techniques. We hope that this review will provide a valuable reference to enable researchers to select the most appropriate technique for detecting PPIs.

Mediator tail module subunits MED16 and MED25 differentially regulate abscisic acid signaling in Arabidopsis

MED25 has been implicated as a negative regulator of the abscisic acid(ABA)signaling pathway.However,it is unclear whether other Mediator subunits could associate with MED25 to participate in the ABA response.Here,we used affinity purification followed by mass spectrometry to uncover Mediator subunits that associate with MED25 in transgenic plants.We found that at least26 Mediator subunits,belonging to the head,middle,tail,and CDK8 kinase modules,were copurified with MED25 in vivo.Interestingly,the tail module subunit MED16 was identified to associate with MED25 under both mock and ABA treatments.We further showed that the disruption of MED16 led to reduced ABA sensitivity compared to the wild type.Transcriptomic analysis revealedthattheexpressionofseveral ABA-responsive genes was significantly lower in med16 than those in wild type.Furthermore,we discovered that MED16 may possibly compete with MED25 to interact with the key transcription factor ABA INSENSITIVE 5(ABI5)to positively regulate ABA signaling.Consistently,med16 and med25 mutants displayed opposite phenotypes in ABA response,cuticle permeability,and differential ABI5-mediated EM1 and EM6 expression.Together,our data indicate that MED16 and MED25 differentially regulate ABA signaling byantagonisticallyaffectingABI5-mediated transcription in Arabidopsis.

The blue light receptor CRY1 interacts with GID1 and DELLA proteins to repress gibberellin signaling and plant growth

Improvements in plant architecture,such as reduced plant height under high-density planting,are important for agricultural production.Light and gibberellin(GA)are essential external and internal cues that affect plant architecture.In this study,we characterize the direct interaction of distinct receptors that link light and GA signaling in Arabidopsis(Arabidopsis thaliana)and wheat(Triticum aestivum L.).We show that the light receptor CRY1 represses GA signaling through interaction with all five DELLA proteins and promotion of RGA protein accumulation in Arabidopsis.Genetic analysis shows that CRY1-mediated growth repression is achieved by means of the DELLA proteins.Interestingly,we find that CRY1 also directly interacts with the GA receptor GID1 to competitively inhibit the GID1-GAI interaction.We also show that overexpression of TaCRY1a reduces plant height and coleoptile growth in wheat and that TaCRY1a interacts with both TaGID1 and Rht1 to competitively attenuate the TaGID1-Rht1 interaction.Based on these findings,we propose that the photoreceptor CRY1 competitively inhibits the GID1-DELLA interaction,thereby stabilizing DELLA proteins and enhancing their repression of plant growth.

铁电突触器件及其应用的研究进展

类脑计算是后摩尔时代集成电路发展的重要方向,开发能够模拟理想突触行为的人工突触器件是构建神经元-突触-神经元连接方式的类脑计算芯片的关键.铁电薄膜材料具有独特的非易失性极化,极化的可塑性与生物突触的可塑性十分类似,因此铁电突触器件近年来受到了广泛关注.本文从器件突触功能模拟和类脑计算应用两个方面对铁电突触器件的研究进展进行了综述.结果表明,铁电突触器件具有两端和三端两种典型结构.除了能有效模拟生物突触功能,铁电突触器件还具有结构简单、功耗低、稳定性高、开关比大及编程速度快等优点.在应用层面,基于铁电突触的神经网络在图像识别方面的研究取得了一系列进展.此外铁电突触还被应用于触觉和视觉仿生.虽然取得了丰富的研究进展,但铁电突触器件目前仍停留在原理的提出和实验验证阶段,在突触性能调控机理、可靠性评价标准、阵列结构优化设计、高密度集成工艺、神经形态计算架构设计、新颖应用场景拓展等方面的研究都存在不小的挑战,这些也是未来铁电突触研究所要聚焦的方向.

Facile synthesis and electrochemical properties of layered Li[Ni1/3Mn1/3Co1/3]O2 as cathode materials for lithium-ion batteries

A layered oxide Li[Ni1/3Mn1/3Co1/3]O2 was synthesized by an oxalate co- precipitation method. The morphology, structural and composition of the as-papered samples synthesized at different calcination temperatures were investigated. The results indicate that calcination temperature of the sample at 850℃ can improve the integrity of structural significantly. The effect of calcination temperature varying from 750℃ to 950℃ on the electrochemical performance of Li[Ni1/3Mn1/3Co1/3]O2, cathode material of lithiumion batteries, has been investigated. The results show that Li[Ni1/3Mn1/3Co1/3]O2 calcined at 850℃ possesses a higher capacity retention and better rate capability than other samples. The reversible capacity is up to 178.6 mA.h.g-1, and the discharge capacity still remains 176.3 mA-h.g-1 after 30 cycles. Moreover, our strategy provides a simple and highly versatile route in fabricating cathode materials for lithium-ion batteries.

The Jasmine(Jasminum sambac)Genome Provides Insight into the Biosynthesis of Flower Fragrances and Jasmonates

Jasminum sambac(jasmine flower),a world-renowned plant appreciated for its exceptional flower fragrance,is of cultural and economic importance.However,the genetic basis of its fragrance is largely unknown.Here,we present the first de novo genome assembly of J.sambac with 550.12 Mb(scaffold N50=40.10 Mb)assembled into 13 pseudochromosomes.Terpene synthase(TPS)genes associated with flower fragrance are considerably amplified in the form of gene clusters through tandem duplications in the genome.Gene clusters within the salicylic acid/benzoic acid/theobromine(SABATH)and benzylalcohol O-acetyltransferase/anthocyanin O-hydroxycinnamoyltransferases/anthranilate N-hydroxycinnamoyl/benzoyltransferase/deacetylvindoline 4-O-acetyltransferase(BAHD)superfamilies were identified to be related to the biosynthesis of phenylpropanoid/benzenoid compounds.Several key genes involved in jasmonate biosynthesis were duplicated,causing an increase in copy numbers.In addition,multi-omics analyses identified various aromatic compounds and many genes involved in fragrance biosynthesis pathways.Furthermore,the roles of JsTPS3 in b-ocimene biosynthesis,as well as JsAOC1 and JsAOS in jasmonic acid biosynthesis,were functionally validated.The genome assembled in this study for J.sambac offers a basic genetic resource for studying floral scent and jasmonate biosynthesis,and provides a foundation for functional genomic research and variety improvements in Jasminum.

An Effective and Inducible System of TAL Effector-Mediated Transcriptional Repression in Arabidopsis

Dear Editor,Gene regulation in model organisms is critical for gene function analysis and is thus essential for human health and agricultural production. Therefore, several molecular tools have been developed to regulate gene expression at the transcriptional and post-transcriptional levels. In recent years, the transcription activator-like effector （TALE）, which is predominantly found in Xanthomonas.

Molecular mechanism analysis of ZmRL6 positively regulating drought stress tolerance in maize

MYB-related genes,a subclass of MYB transcription factor family,have been documented to play important roles in biological processes such as secondary metabolism and stress responses that affect plant growth and development.However,the regulatory roles of MYB-related genes in drought stress response remain unclear in maize.In this study,we discovered that a 1R-MYB gene,ZmRL6,encodes a 96-amino acid protein and is highly drought-inducible.We also found that it is conserved in both barley(Hordeum vulgare L.)and Aegilops tauschii.Furthermore,we observed that overexpression of ZmRL6 can enhance drought tolerance while knock-out of ZmRL6 by CRISPR-Cas9 results in drought hypersensitivity.DAP-seq analyses additionally revealed the ZmRL6 target genes mainly contain ACC GTT,TTA CCA AAC and AGC CCG AG motifs in their promoters.By combining RNA-seq and DAP-seq results together,we subsequently identified eight novel target genes of ZmRL6 that are involved in maize’s hormone signal transduction,sugar metabolism,lignin synthesis,and redox signaling/oxidative stress.Collectively,our data provided insights into the roles of ZmRL6 in maize’s drought response.

Beyond stress response:OST1 opening doors for plants to grow

The sucrose non-fermenting 1(SNF1)-related protein kinase 2(SnRK2)family members have been discovered to regulate abiotic stress response via the abscisic acid(ABA)-independent and dependent signaling pathways.SnRK2.6,also known as Open Stomata 1(OST1),is a serine/threonine protein kinase that plays critical roles in linking ABA receptor complexes and downstream components such as transcription factors and anion channels to regulate stress response.Asides from its well-known regulatory roles in stomatal movement and cold stress response,OST1 has also been demonstrated recently to modulate major developmental roles of flowering and growth in plants.In this review,we will discuss about the various roles of OST1 as well as the‘doors’that OST1 can‘open’to help plants perform stress adaptation.Therefore,we will address how OST1 can regulate stomata apertures,cold stress tolerance as well as other aspects of its emerging roles such as balancing flowering and root growth in response to drought.