A glycine-rich nuclear effector VdCE51 of Verticillium dahliae suppresses plant immune responses by inhibiting the accumulation of GhTRXH2

Verticillium dahliae is an important soil-borne fungal pathogen that causes great yield losses in many cash crops.Effectors of this fungus are known to regulate plant immunity but the mechanism much remains unclear.A glycine-rich nuclear effector,VdCE51,was able to suppress immune responses in tobacco against Botrytis cinerea and Sclerotinia sclerotiorum.This effector was a required factor for full virulence of V.dahliae,and its nuclear localization was a requisite for suppressing plant immunity.The thioredoxin GhTRXH2,identified as a positive regulator of plant immunity,was a host target of VdCE51.Our findings show a virulence regulating mechanism whereby the secreted nuclear effector VdCE51 interferes with the transcription of PR genes,and the SA signaling pathway by inhibiting the accumulation of GhTRXH2,thus suppressing plant immunity.

Comparative analysis of SIMILAR to RCD ONE(SRO)family from tetraploid cotton species and their diploid progenitors depict their significance in cotton growth and development

Background SRO(Similar to RCD1)genes family is largely recognized for their importance in the growth,develop-ment,and in responding to environmental stresses.However,genome-wide identification and functional characteri-zation of SRO genes from cotton species have not been reported so far.Results A total of 36 SRO genes were identified from four cotton species.Phylogenetic analysis divided these genes into three groups with distinct structure.Syntenic and chromosomal distribution analysis indicated uneven distribu-tion of GaSRO,GrSRO,GhSRO,and GbSRO genes on A2,D5 genomes,Gh-At,Gh-Dt,Gb-At,and Gb-Dt subgenomes,respectively.Gene duplication analysis revealed the presence of six duplicated gene pairs among GhSRO genes.In promoter analysis,several elements responsive to the growth,development and hormones were found in GhSRO genes,implying gene induction during cotton growth and development.Several miRNAs responsive to plant growth and abiotic stress were predicted to target 12 GhSRO genes.Organ-specific expression profiling demonstrated the roles of GhSRO genes in one or more tissues.In addition,specific expression pattern of some GhSRO genes dur-ing ovule development depicted their involvement in these developmental processes.Conclusion The data presented in this report laid a foundation for understanding the classification and functions of SRO genes in cotton.

Spatial variation and prediction of forest biomass in a heterogeneous landscape

Large areas assessments of forest bioinass distribution are a challenge in heterogeneous landscapes, where variations in tree growth and species composition occur over short distances. In this study, we use statistical and geospatial modeling on densely sample.d forest biomass data to analyze the relative importance of ecological and physiographic variables as determinants of spatial variation of forest biomass in the environmentally heterogeneous region of the Big Sur, California. We estimated biomass in 280 forest Plots （one plot per 2.85 km2） and meas- ured an array of ecological （vegetation community type, distance to edge, amount of surrounding non-forest vegetation, soil properties, fire history） and physiographic drivers （elevation, potential soil moisture and solar radiation, proximity to the coast） of tree growth at each plot location. Our geostatistical analyses revealed that biomass distribution is spatially structured and autocorrelated up to 3.1 kin. Regression tree （RT） models showed that both physiographic and ecological factors influenced bio- mass distribution. Across randomly selected sample densities （sample size 112 to 280）, ecological effects of vegetation community type and distance to forest edge, and physiographic effects of elevation, potential soil moisture and solar radiation were the most consistent predictors of biomass. Topographic moisture index and potential solar radiation had apositive effect on biomass, indicating the importance of topographically- mediated energy and moisture on plant growth and biomass accumula- tion. RT model explained 35% of the variation in biomass and spatially autocorrelated variation were retained in regession residuals. Regression kriging model, developed from RT combined with kriging of regression residuals, was used to map biomass across the Big Sur. This study dem- onstrates how statistical and geospatial modeling can be used to dis- criminate the relative importance of physiographic and ecologic effects on forest biomass and develop spatial models to predict and map biomass distribution across a heterogeneous landscape.

Evaluation of Potential Cashew Clones for Utilization in Ghana

Cashew (Anacardium occidentale L) is an important cash crop cultivated by about 3 million households in Africa and serves as the livelihood for many African farmers, especially Ghana. Despite the importance of cashew as a commodity crop with increasing cultivation in Northern Ghana, the crop is challenged with problems such as, low and variable nut yields, low kernel out turn percentage and susceptibility to insect pests as a result of establishing cashew farms with unselected seeds. In order to address the challenges, the Cocoa Research Institute of Ghana established a clonal evaluation trial in Northern Ghana (dry savanna vegetation) to indentify promising clones for subsequent distribution to cashew farmers as an interim measure. The trials consisted of ten different clones planted in Randomised Completed Block Design (RCBD) with four replicates. Parameters evaluated were yield, yield efficiency, nut weight, percentage out turn and canopy area. Data analysis was performed with Gen Stat version 11.0 and the results revealed significant differences (P < 0.05) in the performance of the clones in all the parameters considered. Such differences allowed the identification of promising clones over other clones tested. A few clones combined two or three traits (parameters) which were significantly different from the rest of the clones evaluated. No single clone was found to be significantly different from the rest in terms of all the parameters considered. However a greater proportion of the clones were found to produce yields far above average yields recorded by unselected cashew trees in farmers’ fields. Clones W266 and W278 seem outstanding for most of the parameters considered, though not exclusive.

Deciphering Rice Lesion Mimic Mutants to Understand Molecular Network Governing Plant Immunity and Growth

Plant lesion mimic mutants(lmms)generally possess autoimmunity and hypersensitive response(HR)-like cell death in the absence of biotic or abiotic stress.They have attracted much attention because they are useful tools for deciphering the interaction between defense signaling and growth.Recent studies have identified more than 30 lmms involved in the plant immune response and cell death in rice.Genes underlying these lmms,coding for diverse types of proteins,mainly regulate transcription,protein translation and modification,vesicular trafficking and catalyzation of metabolism.Here,we presented an overview of the most recent advances on the study of lmms in rice and proposed a perspective on potential utilization of LMM genes in agriculture.

Creating large EMS populations for functional genomics and breeding in wheat

Wheat germplasm is a fundamental resource for basic research,applied studies,and wheat breeding,which can be enriched normally by several paths,such as collecting natural lines,accumulating breeding lines,and introducing mutagenesis materials.Ethyl methane sulfonate(EMS)is an alkylating agent that can effectively introduce genetic variations in a wide variety of plant species.In this study,we created a million-scale EMS population(MEP)that started with the Chinese wheat cultivars‘Luyan 128’,‘Jimai 38’,‘Jimai 44’,and‘Shannong 30’.In the M1 generation,the MEP had numerous phenotypical variations,such as>3,000 chlorophyll-deficient mutants,2,519 compact spikes,and 1,692 male sterile spikes.There were also rare mutations,including 30 independent tillers each with double heads.Some M1 variations of chlorophyll-deficiency and compact spikes were inheritable,appearing in the M2 or M3 generations.To advance the entire MEP to higher generations,we adopted a single-seed descendent(SSD)approach.All other seed composites of M2 were used to screen other agronomically important traits,such as the tolerance to herbicide quizalofop-P-methyl.The MEP is available for collaborative projects,and provides a valuable toolbox for wheat genetics and breeding for sustainable agriculture.

The Role of the Plasma Membrane H＋-ATPase in Plant-Microbe Interactions

Plasma membrane （PM） H＋-ATPases are the primary pumps responsible for the establishment of cellular mem- brane potential in plants. In addition to regulating basic aspects of plant cell function, these enzymes contribute to sig- naling events in response to diverse environmental stimuli. Here, we focus on the roles of the PM H＋-ATPase during plant- pathogen interactions. PM H＋-ATPases are dynamically regulated during plant immune responses and recent quantitative proteomics studies suggest complex spatial and temporal modulation of PM H＋-ATPase activity during early pathogen recognition events. Additional data indicate that PM H＋-ATPases cooperate with the plant immune signaling protein RIN4 to regulate stomatal apertures during bacterial invasion of leaf tissue. Furthermore, pathogens have evolved mechanisms to manipulate PM H＋-ATPase activity during infection. Thus, these ubiquitous plant enzymes contribute to plant immune responses and are targeted by pathogens to increase plant susceptibility.

Plant Immune Mechanisms:From Reductionistic to Holistic Points of View

After three decades of the amazing progress made on molecular studies of plant-microbe interactions(MPMI),we have begun to ask ourselves"what are the major questions still remaining?"as if the puzzle has only a few pieces missing.Such an exercise has ultimately led to the realization that we still have many more questions than answers.Therefore,it would be an impossible task for us to project a coherent"big picture"of the MPMI field in a single review.Instead,we provide our opinions on where we would like to go in our research as an invitation to the community to join us in this exploration of new MPMI frontiers.

Structural dynamics of a plant NLR resistosome:transition from autoinhibition to activation

Despite the lack of a cellular,adaptive immune system,plants share with animals an innate immune system and can effectively fight off pathogen attack using two layers of defense response:the first layer consists of plasma membrane-localized pattern recognition receptors(PRRs)that recognize pathogen-associated molecular patterns(PAMPs)and can mount a pattern-triggered immunity(PTI);the second layer comprises cytoplasmic nucleotide-binding,leucine-rich repeats receptors(NLRs)that recognize pathogensecreted effectors and mount an effector-triggered immunity(ETI)(Shamrai,2014).Plants contain hundreds of NLR genes constituting one of the largest families of genes.Because plant NLR genes can mount the strongest immune response,often including a hypersensitive response,upon recognition of its cognate effector,they were initially characterized as resistance(R)genes and conform to the genefor-gene hypothesis postulated in 1955(Hh,1955;McHale et al.,2006).The plant NLR-mediated ETI response is thus comparable to the animal inflammatory response.

双分子荧光互补试验研究水稻NH1家族蛋白之间相互作用

NPR1(Non-expresser of pathogenesis related genes 1)是水杨酸(Salicilic acid,SA)介导的系统获得抗性(Sys-temic aquired resistance,SAR)的关键调控因子,在水稻中过量表达拟南芥NPR1和水稻NH1/OsNPR1(NPR1 homo-logue 1)(NPR1的同源物)可增强抗病性。水稻基因组中还有4个NPR1旁系同源物(Paralog),为NH1的家族蛋白。本试验利用双分子荧光互补技术(Bimolecular Fluorescence Complementation,BiFC,or split YFP)研究了水稻NH1家族蛋白之间在活体内的相互作用,发现除NH2外,NH1、NH3、NH4和NH5都会和自身的蛋白互作,产生荧光信号,并且它们还会和家族成员的其他蛋白相互结合产生荧光信号。

NH3基因转化水稻的研究

NPR1(non-expresser of pathogenesis related genes 1)是水杨酸(salicilic acid,SA)介导的植物系统获得抗性(systemic aquired resistance,SAR)的关键调控因子,在水稻中过量表达拟南芥NPR1和水稻NH1/OsNPR1(NPR1homologue 1)(NPR1的同源物)可增强抗病性。水稻基因组中还有4个NPR1旁系同源物(paralog)。为了研究水稻NPR1旁系同源物3,NH3(NPR1 homologue 3),本文利用其自身启动子驱动NH3基因的表达,构建载体将其转入水稻,获得了10个T0代转基因植株。PCR检测证明NH3基因已成功转入水稻中。

OsWRKY62 is a Negative Regulator of Basal and Xa21-Mediated Defense against Xanthomonas orvzae pv. orvzae in Rice

The rice Xa21 gene, which confers resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae （Xoo）, encodes a receptor-like kinase, Few components involved in transducing the Xa21-mediated defense response have yet been identified. Here, we report that XA21 binds to a WRKY transcription factor, called OsWRKY62. The OsWRKY62 gene encodes two splice variants （OsWRKY62.1 and OsWRKY62.2）. OsWRKY62.1：smGFP2 and OsWRKY62.2：smGFP2 fusion pro- teins partially localize to the nucleus. Transgenic plants overexpressing OsWRKY62.1 are compromised in basal defense and Xa21-mediated resistance to Xoo. Furthermore, overexpression of OsWRKY62.1 suppresses the activation of defenserelated genes. These results imply that OsWRKY62 functions as a negative regulator of innate immunity in rice, and serves as a critical mediator of both basal and race-specific defense responses.

Construction of a Rice Glycosyltransferase Phylogenomic Database and Identification of Rice-Diverged Glycosyltransferases

Glycosyltransferases （GTs; EC 2.4.x.y） constitute a large group of enzymes that form glycosidic bonds through transfer of sugars from activated donor molecules to acceptor molecules. GTs are critical to the biosynthesis of plant cell walls, among other diverse functions. Based on the Carbohydrate-Active enZymes （CAZy） database and sequence similarity.searches, we have identified 609 potential GT genes （loci） corresponding to 769 transcripts （gene models） in rice （Oryza sativa）, the reference monocotyledonous species. Using domain composition and sequence similarity, these rice GTs were classified into 40 CAZy families plus an additional unknown class. We found that two Pfam domains of unknown function, PF04577 and PF04646, are associated with GT families GT61 and GT31, respectively. To facilitate functional analysis of this important and large gene family, we created a phylogenomic Rice GT Database （http：//ricephylogenomics. ucdavis.edu/cellwalls/gtJ）. Through the database, several classes of functional genomic data, including mutant lines and gene expression data, can be displayed for each rice GT in the context of a phylogenetic tree, allowing for comparative analysis both within and between GT families. Comprehensive digital expression analysis of public gene expression data revealed that most （-80%） rice GTs are expressed. Based on analysis with Inparanoid, we identified 282 ‘rice-diverged＇ GTs that lack orthologs in sequenced dicots （Arabidopsis thaliana, Populus tricocarpa, Medicago truncatula, and Ricinus communis）. Combining these analyses, we identified 33 rice-diverged GT genes （45 gene models） that are highly expressed in above-ground, vegetative tissues. From the literature and this analysis, 21 of these loci are excellent targets for functional examination toward understanding and manipulating grass cell wall qualities. Study of the remainder may reveal aspects of hormone and protein metabolism that are critical for rice biology. This list of 33 genes and the Rice GT Database will facilitate the study of GTs and cell wall synthesis in rice and other plants.

Identification and characterization of rice blast resistance gene Pid4 by a combination of transcriptomic profiling and genome analysis

Map-based cloning of plant disease resistance (R) genes is time-consuming. Here, we reported the isolation of blast R gene Pid4 using comparative transcriptomic profiling and genome-wide sequence analysis. Pid4 encodes a coiled-coil nucleotide-binding site leucine-rich repeat(CC-NBS-LRR) protein and is constitutively expressed at diverse developmental stages in the rice variety Digu. The Pid4 protein is localized in both the nucleus and cytoplasm. Introduction of Pid4 into susceptible rice cultivars confers race-specific resistance to leaf and neck blast. Amino acid sequence comparison and blast resistance spectrum tests showed that Pid4 is a novel R gene, different from the previously reported R genes located in the same gene cluster. A Pid4 Indel marker was developed to facilitate the identification of Pid4 in different rice varieties. We demonstrated that a plant R gene can be quickly isolated using transcriptomic profiling coupled with genome-wide sequence analysis.

Phosphorylation of the Pseudomonas Effector AvrPtoB by Arabidopsis SnRK2.8 Is Required for Bacterial Virulence

A critical component controlling bacterial virulence is the delivery of pathogen effectors into plant cells during infection.Effectors alter host metabolism and immunity for the benefit of pathogens.Multiple effectors are phosphorylated by host kinases,and this posttranslational modification is important for their activity.We sought to identify host kinases involved in effector phosphorylation.Multiple phosphorylated effector residues matched the proposed consensus motif for the plant calcium-dependent protein kinase(CDPK)and Snf1-related kinase(SnRK)superfamily.The conserved Pseudomonas effector AvrPtoB acts as an E3 ubiquitin ligase and promotes bacterial virulence.In this study,we identified a member of the Arabidopsis SnRK family,SnRK2.8,which interacts with AvrPtoB in yeast and in planta.We showed that SnRK2.8 was required for AvrPtoB virulence functions,including facilitating bacterial colonization,suppression of callose deposition,and targeting the plant defense regulator NPR1 and analyses receptor FLS2.Mass spectrometry analysis revealed that AvrPtoB phosphorylation occurs at multiple serine residues in planta,with S258 phosphorylation significantly reduced in the snrk2.8 knockout.AvrPtoB phospho-'null'mutants exhibited compromised virulence functions and were unable to suppress NPR1 accumulation,FLS2 accumulation,or inhibit FLS2-BAK1 complex formation upon flagellin perception.Taken together,these data identify a conserved plant kinase utilized by a pathogen effector to promote disease.

Strong Suppression of Systemic Acquired Resistance in Arabidopsis by NRR is Dependent on its Ability to Interact with NPRland its Putative Repression Domain

Systemic Acquired Resistance （SAR） in plants confers lasting broad-spectrum resistance to pathogens and requires the phytohormone salicylic acid （SA）. Arabidopsis NPR1/NIM1 is a key regulator of the SAR response. Studies attempting to reveal the function of NPR1 and how it mediates SA signaling have led to isolation of two classes of proteins that interact with NPRI＂ the first class includes rice NRR, Arabidopsis NIMIN1, NIMIN2, and NIMIN3, and tobacco NIMIN2-1ike proteins; the second class belongs to TGA transcription factors. We have previously shown that overexpression of N RR in rice suppresses both basal and Xa21-mediated resistance. In order to test whether NRR affects SA-induced, NPRl-mediated SAR, we have transformed Arabidopsis with the rice NRR gene and tested its effects on the defense response. Expression of NRR in Arabidopsis results in suppression of PR gene induction by SAR inducer and resistance to pathogens. These phenotypes are even more severe than those of the nprl-1 mutant. The ability of NRR to suppress PR gene induction and disease resistance is correlated with its ability to bind to NPR1 because two point mutations in NRR, which reduce NPR1 binding, fail to suppress NPR1. In contrast, wild-type and a mutant NRR, which still binds to NPR1 strongly, retain the ability to suppress the SAR response. Replacing the C-terminal 79 amino acids of NRR with the VP16 activation domain turns the fusion protein into a transcriptional co-activator. These results indicate that NRR binds to NPR1 in vivo in a protein complex to inhibit transcriptional activation of PR genes and that NRR contains a transcription repression domain for active repression.

Characterization of fungal pathogens associated with grapevine trunk diseases in Arkansas and Missouri

Grapevine trunk diseases are a major concern to the wine-and table-grape industries worldwide,limiting both vineyard longevity and productivity.Field surveys conducted throughout the grape-growing regions of Arkansas and Missouri revealed the presence of three economically important grapevine trunk diseases including,Botryosphaeria canker,Eutypa dieback and esca.Morphological studies along with multi-gene phylogenetical analyses confirmed the identification of 15 different fungal taxa associated with different vascular symptoms.These include Botryosphaeria dothidea,Diatrypella sp.,Diplodia seriata,Dothiorella americana,Eutypa lata,Eutypella vitis,Lasiodiplodia missouriana,Lasiodiplodia viticola,Neofusicoccum ribis,Neofusicoccum vitifusiforme,Pestalotiopsis sp.,Pestalotiopsis uvicola,Phaeomoniella chlamydospora,Phomopsis viticola,Schyzophyllum commune,and Togninia minima.All of these represent new records on grapevines in Arkansas and Missouri.Dothiorella americana,L.missouriana and L.viticola are described as new species,and both N.ribis and N.vitifusiforme are first reported as grapevine pathogens in North America.Koch’s postulates confirmed the pathogenicity of all fungal species except S.commune in the interspecific hybrids Vignoles,Chambourcin,Norton,and Traminette.Lasiodiplodia spp.,N.ribis,and P.viticola were the most virulent fungi,while D.americana,E.vitis and N.vitifusiforme were considered to be weak pathogens.This research highlights the importance that grapevine trunk diseases have on grapevine health in growing regions where,due to different climatological conditions,interspecific hybrid cultivars are predominantly grown.

Co-located quantitative trait loci mediate resistance to Agrobacterium tumefaciens, Phytophthora cinnamomi,and P.pini in Juglans microcarpa×J.regia hybrids

Soil-borne plant pathogens represent a serious threat that undermines commercial walnut(Juglans regia)production worldwide.Crown gall,caused by Agrobacterium tumefaciens,and Phytophthora root and crown rots,caused by various Phytophthora spp.,are among the most devastating walnut soil-borne diseases.A recognized strategy to combat soil-borne diseases is adoption of resistant rootstocks.Here,resistance to A.tumefaciens,P.cinnamomi,and P.pini is mapped in the genome of Juglans microcarpa,a North American wild relative of cultivated walnut.Half-sib J.microcarpa mother trees DJUG 31.01 and DJUG 31.09 were crossed with J.regia cv.Serr,producing 353 and 400 hybrids,respectively.Clonally propagated hybrids were genotyped by sequencing to construct genetic maps for the two populations and challenged with the three pathogens.Resistance to each of the three pathogens was mapped as a major QTL on the long arm of J.microcarpa chromosome 4D and was associated with the same haplotype,designated as haplotype b,raising the possibility that the two mother trees were heterozygous for a single Mendelian gene conferring resistance to all three pathogens.The deployment of this haplotype in rootstock breeding will facilitate breeding of a walnut rootstock resistant to both crown gall and Phytophthora root and crown rots.

Construction and Application of Efficient Ac-Ds Transposon Tagging Vectors in Rice

Transposons are effective mutagens alternative to T-DNA for the generation of insertional mutants in many plant species including those whose transformation is inefficient. The current strategies of transposon tagging are usually slow and labor-intensive and yield low frequency of tagged lines. We have constructed a series of transposon tagging vectors based on three approaches： （i） AcTPase controlled by glucocorticoid binding domain/VP16 acidic activation domain/Gal4 DNA-binding domain （GVG） chemical-inducible expression system; （ii） deletion of AcTPase via Cre-lox site-specific recombination that was initially triggered by Ds excision; and （iii） suppression of early transposition events in transformed rice callus through a dual-functional hygromycin resistance gene in a novel Ds element （HPT-Ds）, We tested these vectors in transgenic rice and characterized the transposition events. Our results showed that these vectors are useful resources for functional genomics of rice and other crop plants. The vectors are freely available for the community,

二氧化硫对减少黑皮和绿皮无花果采后损失的效果评价

采后病害限制了新鲜无花果（Ficus carica L.）的贮藏期和货架期寿命。本文研究了应用二氧化硫（SO2）熏蒸或结合二氧化硫（SO2）释放片双重处理对黑皮无花果“Black Mission”和“Brown Turkey”及绿皮无花果“Kadota”和“Sierra”采后腐烂及品质保持的作用效果。