Safety Properties and Probiotic Potential of Bacillus subtilis KATMIRA1933 and Bacillus amyloliquefaciens B-1895

This study reports on the safety and putative probiotic properties of Bacillus amyloliquefaciens B-1895 and Bacillus subtilis KATMIRA1933. According to the bacterial reverse mutation (Ames) test, cell-free supernatants of B. amyloliquefaciens B-1895 and B. subtilis KATMIRA1933 were not mutagenic. The two strains co-aggregated with Escherichia coli and Pseudomonas aeruginosa, and cell-free supernatants inhibited the growth of Streptococcus intermedius and Porphyromonas gingivalis. Endospores of B. amyloliquefaciens B-1895 and B. subtilis KATMIRA1933 were tolerant to 0.3% (w/v) bile salts and survived incubation for 4 h in MRS broth at pH 2.0 to 3.0. The ability of the two strains to produce antimicrobial compounds potentiates their application in health care formulations, personal care products, food and animal feed.

Growth and physiological responses of creeping bentgrass(Agrostis stolonifera)to elevated carbon dioxide concentrations

The atmospheric carbon dioxide level has increased and is predicted to continue increasing,which may affect various aspects of plant growth.The objective of this study was to investigate the effects of doubling the carbon dioxide level on the growth and physiological activities of a widely utilized cool-season turfgrass species,creeping bentgrass(Agrostis stolonifera L.‘Penncross’).‘Penncross’plants were established in fritted clay medium and maintained under well-irrigated and well-fertilized conditions in growth chambers.The plants were exposed to either ambient carbon dioxide concentrations(400±10 mmol L^(-1))or elevated carbon dioxide concentrations(800±10 mmol L^(-1))for 12 weeks.Plants grown under elevated carbon dioxide displayed a significantly faster growth rate of their lateral stems(stolons)and increased shoot and root dry weight but a reduced specific leaf area compared to those plants at ambient carbon dioxide levels.Fast stolon growth is a highly desirable trait for turfgrass establishment and recovery from physical damage.The root length and surface area were also increased due to the elevated CO_(2),which may facilitate water uptake and serve critical drought-avoidance roles when irrigation water is limited.Elevated carbon dioxide caused an increase in the leaf net photosynthetic rate but a reduction in the stomatal conductance and transpiration rate,contributing to improved water use efficiency in creeping bentgrass.Efficient water use is especially important for turfgrass plant survival when irrigation water is limited.Our results suggested that cool-season turfgrass species may greatly benefit from increasingly elevated carbon dioxide concentrations via growth promotion and increasing water use efficiency.

Regulation of nutrient accumulation byγ-aminobutyric acid associated with GABA priming-enhanced heat tolerance in creeping bentgrass

γ-Aminobutyric acid(GABA)is known for its positive effects on improving plant stress tolerance,while the association of its role in regulating nutritional availability and GABA priming-enhanced heat tolerance is not well documented.The objective of this study was to determine whether GABA priming may improve heat tolerance in cool-season grass species involving regulation of plant nutrition for macronutrients and micronutrient elements.Plants of creeping bentgrass(Agrostis stolonifera)(cv.'Penncross')in each pot were treated with 10 mL of water(control)or 0.5 mM GABA(GABA priming)by foliar spray and then subjected to heat stress(35/30°C,day/night)or optimal growth temperature(control)(21/19°C,day/night)(non-stress control)for 30 d in growth chambers.GABA-primed plants had significantly higher endogenous GABA content associated with improved heat tolerance compared to non-treated plants,as reflected by higher leaf cell membrane stability,relative water content,osmotic adjustment,chlorophyll content,photochemical efficiency,and net photosynthetic rate.Plants pretreated with GABA exhibited significantly higher content of nitrogen(N),phosphorus(P),calcium(Ca),sodium(Na),and copper(Cu)but lower content of boron(B)and manganese(Mn)in leaves than non-treated plants under heat stress.The enhanced accumulation of N,P,Ca,Na,and Cu and restricted B and Mn accumulation by GABA priming indicate that GABA could modulate mineral nutrient availability in plants,contributing to improved heat tolerance for creeping bentgrass.

Identification and Characterization of Proteins Associated with Plant Tolerance to Heat Stress

Heat stress is a major abiotic stress limiting plant growth and productivity in many areas of the world. Understanding mechanisms of plant adaptation to heat stress would facilitate the development of heat-tolerant cultivars for improving productivity in warm climatic regions. Protein metabolism involving protein synthesis and degradation is one of the most sensitive processes to heat stress. Changes in the level and expression pattern of some proteins may play an important role in plant adaptation to heat stress. The identification of stress-responsive proteins and pathways has been facilitated by an increasing number of tools and resources, including two-dimensional electrophoresis and mass spectrometry, and the rapidly expanding nucleotide and amino acid sequence databases. Heat stress may induce or enhance protein expression or cause protein degradation. The induction of heat-responsive proteins, particularly heat shock proteins （HSPs）, plays a key role in plant tolerance to heat stress. Protein degradation involving various proteases is also important in regulating plant responses to heat stress. This review provides an overview of recent research on proteomic profiling for the identification of heat-responsive proteins associated with heat tolerance, heat induction and characteristics of HSPs, and protein degradation in relation to plant responses to heat stress.

氯苯嘧啶醇施用对草坪斑枯病致病菌及根际土壤真菌的影响

[目的]本文的目的是深入了解杀菌剂氯苯嘧啶醇施用对草地早熟禾(Poa pratensis L.)夏季草坪斑枯病病菌及根际土壤真菌的影响。[方法]根据真菌内转录间隔区(ITS)基因的种内相对保守和种间差异比较明显的特点,使用Illumina高通量测序技术对氯苯嘧啶醇喷施后草地早熟禾根际土壤微生物宏基因组进行高通量测序。[结果]对照和氯苯嘧啶醇喷施处理的根际土壤分别产生4 851 438和3 037 924条Illumina双末端测序序列,经质量控制与序列比对后分别产生28 219和21 288个代表操作分类单位(OTU)。与对照相比,氯苯嘧啶醇施用后草地早熟禾根际土壤中子囊菌门真菌(Ascomycota)比例减少了18%,而担子菌门真菌(Basidiomycota)增加了32%,壶菌门类真菌(Chytridiomycota)和球囊菌门真菌(Glomeromycota)相对比例无显著变化;草地早熟禾根际土壤中真菌在科的分类单位上减少7个,在属的水平上减少152个,在种的水平上减少200个真菌种(类)。[结论]氯苯嘧啶醇喷施后不仅对草地早熟禾根际土壤中夏季草坪斑枯病致病菌有较强的抑制作用,而且对草地早熟禾根际土壤中疱霉属(Phoma)、小球腔菌属(Leptosphaeria)、镰刀菌属(Fusarium)和瓶霉属(Phialophora)土壤优势真菌有明显抑制作用。

翦股颖AsEXP1基因的抗旱性分析

分析了不同匍匐翦股颖草坪草品种在干旱环境下AsEXP1基因的表达状况,发现AsEXP1基因的表达与草坪草品种的抗旱性呈显著正相关关系,亦即在耐旱草坪草品种中表达,而在不耐旱草坪草品种中不表达。对耐热但不耐旱草坪草品种‘PennA-4’的进一步检测分析发现,AsEXP1基因经高温诱导表达后,显著增强了‘PennA-4’品种的耐旱性。

草坪斑枯病病原菌及其近缘种属的系统发育及基因宏阵列检测

夏季草坪斑枯病是由子囊菌纲巨座壳科真菌Magnaporthe poae在夏季高温高湿环境下引起的一种草坪病害。对来源不同的24个Magnaporthe及其近缘种属Gaeumannomyces菌株的ITS1-5.8S-ITS2测序序列进行比较及系统发育分析。结果表明：M.poae及其近缘种属真菌可分为A和B 2个群：A群由M.oryzae和Pyricularia oryzae菌种组成并形成2个分支,二者亲缘关系较近,且具有侵染寄主植物根部和地上部分的能力。B群由M.salvinii、M.poae、M.rhizophila、G.incrustans和G.graminis种内的2个变种（G.graminis var.graminis和G.graminis var.tritici）组成,B群真菌除M.salvinii外均有侵染寄主根部能力。在草坪环境中,B群真菌种内检测鉴定较A群困难。本研究根据真菌ITS基因的种内序列高度保守,种间差异明显的特点,分别设计了基因宏阵列单体（20~24 bp）、二聚体（40~48 bp）和单体加20个“A”（30~34 bp）3种寡核苷酸基因宏阵列检测探针来快速检测鉴定B群病原真菌。基因宏阵列检测结果表明：设计的检测探针均能准确、特异地检测鉴定B群的3种真菌,检测灵敏度从高到低依次为：二聚体探针、单体加20个“A”探针、单体探针。结论：在草坪土壤环境中,二聚体基因宏阵列检测探针（40~48 bp）对于Magnaporthe及其近缘种属菌株的检测较传统的单体检测探针更为灵敏与准确。

Taxonomic placement of Epichloëpoae sp.nov.and horizontal dissemination to seedlings via conidia

A new Epichloëspecies distributed in Africa,Europe,North America and South America on host genera Bromus,Festuca,Lolium and Poa is described.Stromata,characteristic of the genus,frequently occurred on the reproductive tillers of Poa secunda subsp.juncifolia,but neither perithecia nor mature asci were observed.Conidiogenous cells and conidial characteristics were in the range of Epichloëtyphina.Regions of the genes encodingβ-tubulin(tub2)and translation elongation factor 1-α(tef1)were amplified and sequenced.Phylogenetic analyses of these sequences grouped the Poa secunda subsp.juncifolia endophyte into one group within a non-hybrid Epichloëspecies complex.On the basis of morphology,host range and evolutionary history we propose that this endophyte represents a new species of Epichloë.The name Epichloëpoae is proposed for this endophyte.The infectivity of the conidia produced on plants was evaluated.In the first experiment,using conidia of Epichloëpoae from leaves and endophytefree seeds of Poa secunda subsp.juncifolia we show that when germinating seeds and developing seedlings of the plant were exposed to conidia,28–57%of seedlings became infected by the endophyte.The non-inoculated control plants showed no colonization by the endophyte.In the following spring after vernalization,colonized plants on flowering culms produced stromata with conidia.In the second experiment,using stromal conidia and the same procedure,19–42%of seedlings of Poa secunda subsp.juncifolia became colonized by the endophyte.Our results demonstrate that Epichloëpoae may spread to uninfected grass hosts by conidia frequently formed on the surfaces of plant leaves as well as by conidia formed on stromata.

Endophytic and pathogenic fungi of developing cranberry ovaries from flower to mature fruit:diversity and succession

Culturable fungal population diversity and succession was investigated in developing cranberry ovaries of fruit rot-resistant and rot-susceptible cranberry selections,from flower through mature fruit.Fungi were recovered in culture from 1185 of 1338 ovary tissues collected from June to September,yielding 2255 isolates that represented 42 morphotaxa.During the season,species richness varied from 2 to 17 and 2 to 18 in rot-resistant and rotsusceptible selections,respectively,increasing from wk1 to wk10 and then gradually declining to wk14.Shannon-Wiener diversity index varied from 0.27 to 2.32 in rotresistant and 0.18 to 2.38 in rot-susceptible,and Pielou’s evenness index varied from 0.11 to 0.63 and 0.06 to 0.64 in rot-resistant and rot-susceptible selections,respectively,confirming that diversity of fungi in developing ovaries was similar among rot-resistant and rot-susceptible selections,but varied among sampling time points.Principal component analysis grouped samples collected at the same sampling time point together regardless of rot susceptibility of the selections,and detected the predominant fungal species associated with each stage of development.Successional changes were observed in populations of endophytic,pathogenic and saprophytic fungi throughout the season as ovaries matured.

Phylogeny and taxonomy of Ophiognomonia(Gnomoniaceae,Diaporthales),including twenty-five new species in this highly diverse genus

Species of Ophiognomonia are leaf-inhabiting endophytes,pathogens,and saprobes that infect plants in the families Betulaceae,Fagaceae,Juglandaceae,Lauraceae,Malvaceae,Platanaceae,Rosaceae,Salicaceae,and Sapindaceae.Based on extensive collecting,this speciesrich genus is now known to have a world wide distribution in primarily temperate areas,although some species are known from the subtropics.Analyses of DNA sequences from three markers including guanine nucleotide-binding protein subunit beta-like protein(MS204),translation elongation factor 1α(tef-1α),and the ITS region including ITS1,5.8 S rDNA and ITS2 regions(ITS)were used to define phylogenetic species in Ophiognomonia.Host plant association correlated with these species.Twenty-five new species of Ophiognomonia and two new combinations are proposed with descriptions and illustrations.In addition,descriptions and illustrations are provided for 12 other species of Ophiognomonia.A key is provided to the 45 currently accepted species of Ophiognomonia.The disposition of additional names in Ophiognomonia is also discussed.

Improving ITS sequence data for identification of plant pathogenic fungi

Plant pathogenic fungi are a large and diverse assemblage of eukaryotes with substantial impacts on natural ecosystems and human endeavours.These taxa often have complex and poorly understood life cycles,lack observable,discriminatory morphological characters,and may not be amenable to in vitro culturing.As a result,species identification is frequently difficult.Molecular(DNA sequence)data have emerged as crucial information for the taxonomic identification of plant pathogenic fungi,with the nuclear ribosomal internal transcribed spacer(ITS)region being the most popular marker.However,international nucleotide sequence databases are accumulating numerous sequences of compromised or low-resolution taxonomic annotations and substandard technical quality,making their use in the molecular identification of plant pathogenic fungi problematic.Here we report on a concerted effort to identify high-quality reference sequences for various plant pathogenic fungi and to re-annotate incorrectly or insufficiently annotated public ITS sequences from these fungal lineages.A third objective was to enrich the sequences with geographical and ecological metadata.The results-a total of 31,954 changes-are incorporated in and made available through the UNITE database for molecular identification of fungi(http://unite.ut.ee),including standalone FASTA files of sequence data for local BLAST searches,use in the next-generation sequencing analysis platforms QIIME and mothur,and related applications.The present initiative is just a beginning to cover the wide spectrum of plant pathogenic fungi,and we invite all researchers with pertinent expertise to join the annotation effort.

CCCH protein-PvCCCH69 acted as a repressor for leaf senescence through suppressing ABA-signaling pathway

CCCH is a subfamily of zinc finger proteins involved in plant growth,development,and stresses response.The function of CCCH in regulating leaf senescence,especially its roles in abscisic acid(ABA)-mediated leaf senescence is largely unknown.The objective of this study was to determine functions and mechanisms of CCCH gene in regulating leaf senescence in switchgrass(Panicum virgatum).A CCCH gene,PvCCCH69(PvC3H69),was cloned from switchgrass.Overexpressing PvC3H69 in rice suppressed both natural senescence with leaf aging and dark-induced leaf senescence.Endogenous ABA content,ABA biosynthesis genes(NCED3,NCED5,and AAO3),and ABA signaling-related genes(SnRKs,ABI5,and ABF2/3/4)exhibited significantly lower levels in senescencing leaves of PvC3H69-OE plants than those in WT plants.PvC3H69-suppression of leaf senescence was associated with transcriptional upregulation of genes mainly involved in the light-dependent process of photosynthesis,including light-harvesting complex proteins,PSI proteins,and PSII proteins and downregulation of ABA biosynthesis and signaling genes and senescence-associated genes.PvC3H69 could act as a repressor for leaf senescence via upregulating photosynthetic proteins and repressing ABA synthesis and ABA signaling pathways.

Transcriptomic analysis in Anemone flaccida rhizomes reveals ancillary pathway for triterpene saponins biosynthesis and differential responsiveness to phytohormones

Anemone flaccida Fr. Schmidt is a perennial medicinal herb that contains pentacyclic triterpenoid saponins as the major bioactive constituents. In China, the rhizomes are used as treatments for a variety of ailments including arthritis. However, yields of the saponins are low, and little is known about the plant's genetic background or phytohormonal responsiveness. Using one-quarter of the 454 pyrosequencing information from the Roche GS FLX Titanium platform, we performed a transcriptomic analysis to identify 157 genes putatively encoding 26 enzymes involved in the synthesis of the bioactive compounds. It was revealed that there are two biosynthetic pathways of triterpene saponins in A. flaccida. One pathway depends on β-amyrin synthase and is similar to that found in other plants. The second, subsidiary("backburner") pathway is catalyzed by camelliol C synthase and yields β-amyrin as minor byproduct. Both pathways used cytochrome P450-dependent monooxygenases(CYPs) and family 1 uridine diphosphate glycosyltransferases(UGTs) to modify the triterpenoid backbone. The expression of CYPs and UGTs were quite different in roots treated with the phytohormones methyl jasmonate, salicylic acid and indole-3-acetic acid. This study provides the first large-scale transcriptional dataset for the biosynthetic pathways of triterpene saponins and their phytohormonal responsiveness in the genus Anemone.

Defining the Functional Network of Epigenetic Regulators in Arabidopsis thaliana

Development of ChiP-chip and ChlP-seq technologies has allowed genome-wide high-resolution profiling of chromatin-associated marks and binding sites for epigenetic regulators. However, signals for directing epigenetic modifiers to their target sites are not understood. In this paper, we tested the hypothesis that genome location can affect the involvement of epigenetic regulators using Chromatin Charting （CC） Lines, which have an identical transgene construct inserted at different locations in the Arabidopsis genome. Four CC lines that showed evidence for epigenetic silencing of the luciferase reporter gene were transformed with RNAi vectors individually targeting epigenetic regulators LHP1, MOM1, CMT3, DRD1, DRM2, SUVH2, CLF, and HD1. Involvement of a particular epigenetic regulator in silencing the transgene locus in a CC line was determined by significant alterations in luciferase expression after suppression of the regulator＇s expression. Our results suggest that the targeting of epigenetic regulators can be influenced by genome location as well as sequence context. In addition, the relative importance of an epigenetic regulator can be influenced by tissue identity. We also report a novel approach to predict interactions between epigenetic regulators through clustering analysis of the regulators using alterations in gene expression of putative downstream targets, including endogenous loci and transgenes, in epigenetic mutants or RNAi lines. Our data support the existence of a complex and dynamic network of epigenetic regulators that serves to coordinate and control global gene expression in higher plants.

Kinetics of the Anti-oxidant Response to Salinity in the Halophyte Cakile maritima

The effects of NaCl stress on the activity of anti-oxidant enzymes （superoxide dismutase, catalase （CAT）, peroxidase （POD）, ascorbate peroxidase （APX）, monodehydroascorbate reductase, dehydroascorbate reductase （DHAR）, and glutathione reductase （GR））, anti-oxidant molecules （ascorbate and glutathione）, and parameters of oxidative stress （malondialdehyde （MDA）, electrolyte leakage, and H2O2 concentrations） were investigated in Cakile maritima, a halophyte frequent along the Tunisian seashore. Seedlings were grown in the presence of salt （100, 200, and 400 mmol/L NaCl）. Plants were harvested periodically over 20 days. Growth was maximal in the presence of 0-100 mmol/L NaCl. At 400 mmol/L NaCl, growth decreased significantly. The salt tolerance of C. maritima, at moderate salinities, was associated with the lowest values of the parameters indicative of oxidative stress, namely the highest activities of POD, CAT, APX, DHAR, and GR and high tissue content of ascorbate and glutathione. However, prolonged exposure to high salinity resulted in a decrease in anti-oxidant activities and high MDA content, electrolyte leakage, and H2O2 concentrations. These results suggest that anti-oxidant systems participate in the tolerance of C. maritima to moderate salinities.

Occultocarpon,a new monotypic genus of Gnomoniaceae on Alnus nepalensis from China

Microfungi in the Gnomoniaceae(Diaporthales,Ascomycetes)comprise species commonly reported as pathogens and endophytes on trees and herbaceous hosts primarily from temperate forests of North America,Europe,and Japan.The diversity of Gnomoniaceae in China is poorly known,although several plant families that occur there specifically the Betulaceae are considered important hosts.An exploratory trip to Yunnan,China,resulted in the discovery of several members of the Gnomoniaceae.In this paper a new monotypic genus,Occultocarpon and its species,O.ailaoshanense,are described and illustrated.A phylogeny based on three genes(LSU,rpb2,tef1-α)reveals that O.ailaoshanense belongs to the Gnomoniaceae and forms a branch distinct from the currently known genera.Occultocarpon ailaoshanense is characterized by perithecia with thin,central to eccentric necks in groups embedded in a stroma and oblong elliptical-elongated,one-septate ascospores.Occultocarpon ailaoshanense occurs on the bark of branches of Alnus nepalensis(Betulaceae)in Yunnan,China.

Focusing on the Focus： What Else beYOnd the Master Switches for Polar Cell Growth？

Cell polarity, often associated with polarized cell expansion/growth in plants, describes the uneven distribution of cellular components, such as proteins, nucleic acids, signaling molecules, vesicles, cytoskeletal elements, and organelles, which may ultimately modulate cell shape, structure, and function. Pollen tubes and root hairs are model cell systems for studying the molecular mechanisms underlying sustained tip growth. The formation of intercalated epidermal pavement cells requires excitatory and inhibitory pathways to coordinate cell expansion within single cells and between cells in contact. Strictly controlled cell expansion is linked to asymmetric cell division in zygotes and stomatal lineages, which require integrated processes of pre-mitotic cellular polarization and division asymmetry. While small GTPase ROPs are recognized as fundamental signaling switches for cell polarity in various cellular and developmental processes in plants, the broader molecular machinery underpinning polarity establishment required for asymmetric division remains largely unknown. Here, we review the widely used ROP signaling pathways in cell polar growth and the recently discovered feedback loops with auxin signaling and PIN effluxers. We discuss the conserved phosphorylation and phospholipid signaling mechanisms for regulating uneven distribution of proteins, as well as the potential roles of novel proteins and MAPKs in the polarity establishment related to asymmetric cell division in plants.