Plant Leaves

Plants are fundamentally important to life. Key research areas in plant science include plant species identification, weed classification using hyper spectral images, monitoring plant health and tracing leaf growth, and the semantic interpretation of leaf information. Botanists easily identify plant species by discriminating between the shape of the leaf, tip, base, leaf margin and leaf vein, as well as the texture of the leaf and the arrangement of leaflets of compound leaves. Because of the increasing demand for experts and calls for biodiversity, there is a need for intelligent systems that recognize and characterize leaves so as to scrutinize a particular species, the diseases that affect them, the pattern of leaf growth, and so on. We review several image processing methods in the feature extraction of leaves, given that feature extraction is a crucial technique in computer vision. As computers cannot comprehend images, they are required to be converted into features by individually analyzing image shapes, colors, textures and moments. Images that look the same may deviate in terms of geometric and photometric variations. In our study, we also discuss certain machine learning classifiers for an analysis of different species of leaves.

Antifeedant, larvicidal and pupicidal activities of hexane, chloroform and ethyl acetate extracts of Atlantia monophylla leaf were studied against third instar larvae of Helicoverpa armigera. All the extracts showed feeding deterrent, larvicidal and pupicidal effects in a dose dependent manner. Significant antifeedant, larvicidal and pupicidal activities were observed only in hexane extract. The hexane extract was subjected to fractionation using silica gel column chromatography. Twelve fractions were obtained. Ninth fraction showed good antifeedant, larvicidal, pupicidal activities and disrupted adult emergence. LC 50 value was at 384.57 ppm for larval mortality. The active fraction at 1000 ppm concentration had 100% pupal mortality.

Two angiotensin II (Ang II)–specific receptors, AGTR1 and AGTR2, are expressed in the mammalian brain. Ang II actions on blood pressure regulation, water electrolyte balance, and hormone secretion are primarily mediated by AGTR1. The function of AGTR2 remains unclear. Here, we show that expression of the AGTR2 gene was absent in a female patient with mental retardation (MR) who had a balanced X;7 chromosomal translocation. Additionally, 8 of 590 unrelated male patients with MR were found to have sequence changes in the AGTR2 gene, including one frameshift and three missense mutations. These findings indicate a role for AGTR2 in brain development and cognitive function.

We describe two newly discovered fungi living on the adaxial leaf surface of plants belonging to the Convolvulaceae, Ipomoea asarifolia and Turbina corymbosa. The fungi apparently are epibionts because hyphae were never observed to penetrate epidermal cells or stomata of their respective host plants, and most remarkably are intimately associated with secretory glands on the leaf surface. Hyphae and structures resembling chlamydospores and synnemata (but lacking conidia), formed by both fungal species are phenotypically nearly indistinguishable after in vitro growth or when examined in vivo on the leaf surface. Phylogenetic trees based on aligned DNA sequences from nuclear genes for b-tubulin (tubB) and RNA Polymerase II subunit 1 (rpbA), and the mitochondrial gene for ATP synthase F0 subunit A (atp6), grouped the fungal species in a clade within the Clavicipitaceae. Clavicipitaceous fungi isolated from the two different plant species could be distinguished by their atp6 and rpbA sequences, and nuclear genes for c-actin (actG), translation elongation factor 1-a (tefA), and 4-(c,c-dimethylallyl)tryptophan synthase (dmaW), the determinant step in ergoline (i.e. ergot) alkaloid biosynthesis. Based on these findings we propose a new fungal genus, Periglandula, gen. nov., and describe two new species, Periglandula ipomoeae sp. nov., from host plant I. asarifolia, and Periglandula turbinae sp. nov., from T. corymbosa.

Mixed infection with the SON41 strain of Potato virus Y (PVY-SON41) in tomato increased accumulation of RNAs of strains Fny and LS of Cucumber mosaic virus (CMV-Fny and CMV-LS, respectively) and enhanced disease symptoms. By contrast, replication of PVY-SON41 was downregulated by CMV-Fny and this was due to the CMV-Fny 2b protein. The CMV-FnyΔ2b mutant was unable to systemically invade the tomato plant because its movement was blocked at the bundle sheath of the phloem. The function needed for invading the phloem was complemented by PVY-SON41 in plants grown at 22°C whereas this complementation was not necessary in plants grown at 15°C. Mutations in the 2b protein coding sequence of CMV-Fny as well as inhibition of translation of the 2a/2b overlapping region of the 2a protein lessened both the accumulation of viral RNAs and the severity of symptoms. Both of these functions were complemented by PVY-SON41. Infection of CMV-Fny supporting replication of the Tfn-satellite RNA reduced th...

The methanol extract of the leaves of P. incarnata was evaluated for its antiasthmatic effects against acetylcholine chloride (Ach)-induced-bronchospasm in guinea-pigs at doses of 50, 100 and 200 mg/kg. Using a 7-day treatment regimen, significant prevention of dyspnoea-related-convulsions was noted in the animals treated with a 100 mg/kg dose of this extract. No preventive effect was exhibited by the 50 mg/kg dose and at a higher dose, i.e. 200 mg/kg, the preventive effects against Ach-chloride-induced-dyspnoea were also reduced. This may be due to defective alpha-adrenoceptor function reported after excessive or continuous administration of an alpha-receptor agonist.

Despite the great interest concerning the relationship between species diversity and ecosystem functioning, there is virtually no knowledge as to how the diversity of decomposer microbes influences the decomposition rate of soil organic matter. We established a microcosm study in which the number of soil fungi was investigated in relation to the system's ability to (i) degrade raw coniferous forest humus, and (ii) use resources that were either added to the systems or released into the soils after a disturbance (drought). With the exception of the most diverse treatment, in each of the six replicates of each of the six diversity treatments (1, 3, 6, 12, 24 or 43 taxa), fungal taxa were randomly chosen from a pool of 43 commonly isolated fungal species of raw humus. Two months after initiation of the study CO 2 production increased as fungal diversity increased, but in the species-poor end of the diversity gradient only. Addition of various energy resources to the microcosms generally increased the level of soil respiration but did not affect the shape of the diversity-CO 2 -production curve. Rewetting the soil after severe drought resulted in a rapid flush of CO 2 , particularly in the most diverse communities. The biomass of the fungi in the non-disturbed soils, and soil NH 4 -N concentration and soil pH in both disturbed and non-disturbed systems were slightly but significantly higher in the diverse than in the simple systems. Fungal species richness had no influence on the organic matter content of the humus at the end of the experiment. The results suggest that the functional efficiency of fungal communities can increase with the number of fungal taxa. This diversity effect was, however, significant at the species-poor end of the diversity gradient only, which implies considerable functional equivalency (redundancy) among the decomposer fungi.

The objective of the present study was to determine the oxidative stress caused by hexavalent chromium (Cr [VI]), the chromium (Cr) uptake, and the Cr speciation in Convolvulus arvensis L. plants grown in hydroponics media containing either Cr(VI) or Cr(III). The results demonstrated that C. arvensis plants exposed to Cr(VI) concentrations ranging from 0 to 40 mg/L expressed higher ascorbate peroxidase specific activity in roots than in shoots. On the other hand, catalase activity monitored in plants exposed to 2 mg/L of Cr(VI) for 24 h increased in roots after a few hours of exposure. However, catalase activity in shoots revealed a decrement almost immediately after treatment was initiated. The results from x-ray absorption spectroscopic studies indicated that the oxidation state of the supplied Cr(III) remained the same in plant tissues. The supplied Cr(VI), however, was reduced to the trivalent form in plant tissues. The results of inductively coupled plasma/optical emission spectroscopy demonstrated that after 5 d, the roots of plants exposed to 40 mg/L of Cr(III) or Cr(VI) accumulated approximately 25,000 and 3,500 mg/kg dry weight of Cr, respectively. Nevertheless, shoots concentrated 1,500 and 2,000 mg/kg dry weight of Cr from Cr(III) and Cr(VI), respectively, which indicated that Cr moved faster into C. arvensis plants when supplied as Cr(VI).

Synthesis of metallic and semiconductor nanoparticles through physical and chemical routes has been extensively reported. However, green synthesized metal nanoparticles are currently in the limelight due to the simplicity, cost-effectiveness and eco-friendliness of their synthesis. This study explored the use of aqueous leaf extract of Costus afer in the synthesis of silver nanoparticles (CA-AgNPs). The optical and structural properties of the resulting silver nanoparticles were studied using UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infra-red spectrophotometer (FTIR). TEM images of the silver nanoparticles confirmed the existence of monodispersed spherical nanoparticles with a mean size of 20 nm. The FTIR spectra affirmed the presence of phytochemicals from the Costus afer leaf extract on the surface of the silver nanoparticles. The electrochemical characterization of a CA-AgNPs/multiwalled carbon nanot...

The leaf economics spectrum (LES) represents a suite of intercorrelated leaf traits concerning construction costs per unit leaf area, nutrient concentrations, and rates of carbon fixation and tissue turnover. Although broad trade-offs among leaf structural and physiological traits have been demonstrated, we still do not have a comprehensive view of the fundamental constraints underlying the LES trade-offs. Here, we investigated physiological and structural mechanisms underpinning the LES by analysing a novel data compilation incorporating rarely considered traits such as the dry mass fraction in cell walls, nitrogen allocation, mesophyll CO2 diffusion and associated anatomical traits for hundreds of species covering major growth forms. The analysis demonstrates that cell wall constituents are major components of leaf dry mass (18-70%), especially in leaves with high leaf mass per unit area (LMA) and long lifespan. A greater fraction of leaf mass in cell walls is typically associated...

The plant steroid hormones brassinosteroids (BRs) play important roles in plant growth and responses to stresses. The up-regulation of pathogen resistance by BR signaling has been analyzed, but the relationship between BR and insect herbivores remains largely unclear. BIL1/BZR1 is a BR master transcription factor known to be involved in the regulation of plant development through work conducted on a gain of function mutation. Here, we analyzed the function of BIL1/BZR1 in response to insect feeding and demonstrated that resistance against thrip feeding was increased in the bil1-1D/bzr1-1D mutant compared to wild-type. We generated Lotus japonicus transgenic plants that over-express the Arabidopsis bil1/bzr1 mutant, Lj-bil1/bzr1-OX. The Lj-bil1/bzr1-OX plants showed increased resistance to thrip feeding. The expression levels of the jasmoninc acid (JA)-inducible VSP genes were increased in both Arabidopsis bil1-1D/bzr1-1D mutants and L. japonicus Lj-bil1/bzr1-OX plants. The resistanc...

Myrosinases (␤-thioglucoside glucohydrolase, TGG; EC 3.2.1.147) catalyze the hydrolysis of glucosinolates, a structurally distinct group of nitrogen-and sulfur-containing secondary metabolites, to give a chemically unstable intermediate, glucose and sulfate. This catalysis initiates a chemical defense in crucifer plants as a response to the tissue-damaging activities of herbivores and pathogens. To characterize the individual and collective biochemical properties of the myrosinase enzymes found in the aerial tissues of Arabidopsis thaliana, we purified TGG1 and TGG2, which share 73% amino acid identity, individually from T-DNA insertion lines of Arabidopsis using lectin affinity and anion exchange chromatography. Electrophoresis under denaturing conditions and the mobility of nondenatured TGG1 and TGG2 protein on gel filtration chromatography indicated that the native proteins exist as dimers of 150 and 126 kDa, respectively. Despite their relatively similar kinetic parameters, both enzymes had distinct physicochemical properties such as extractability in low ionic strength buffer and electrophoretic mobility following deglycosylation treatment. Deglycosylation under nondenaturing conditions had limited effects on TGG1 and no effect on TGG2 activity. Both enzymes functioned across a broad range of temperatures (up to 60 • C) and pH values (5-10). These results demonstrate that myrosinases have the ability to function in environments like the digestive tract of insect herbivores that are significantly different from the environment in a damaged plant.

Cytoplasmic lipid droplets (LDs) are found in all types of plant cells; they are derived from the endoplasmic reticulum and function as a repository for neutral lipids, as well as serving in lipid remodelling and signalling. However, the mechanisms underlying the formation, steady-state maintenance and turnover of plant LDs, particularly in non-seed tissues, are relatively unknown. Previously, we showed that the LD-associated proteins (LDAPs) are a family of plant-specific, LD surface-associated coat proteins that are required for proper biogenesis of LDs and neutral lipid homeostasis in vegetative tissues. Here, we screened a yeast two-hybrid library using the Arabidopsis LDAP3 isoform as 'bait' in an effort to identify other novel LD protein constituents. One of the candidate LDAP3-interacting proteins was Arabidopsis At5g16550, which is a plant-specific protein of unknown function that we termed LDIP (LDAP-interacting protein). Using a combination of biochemical and cellu...

The present study reports the potential remediation of cesium (Cs) using napiergrass, which produces the largest biomass among the herbaceous plants in hydroponic culture containing stable Cs (Cs-133) at concentrations of 50, 150, 300, 1000, and 3000 mM using cesium chloride (CsCl), with 0 mM Cs as a control concentration. Plant height was significantly decreased in higher Cs-treated conditions (300, 1000, and 3000 mM Cs) at 7 weeks after treatment (WAT), but tiller numbers tended to increase compared with the control plant. No significant difference was observed in the aboveground dry matter weight in all Cs treatments throughout the study period. Cs content in the roots, leaf blades, and leaf sheaths clearly increased with increasing Cs concentration in the solutions. Cs content in the aboveground parts (leaf blades and leaf sheaths) was consistently higher than in the roots at concentration of 3000 mM. Total Cs contents in the aboveground parts were 6305 and 26,365 mg kg À 1 at 7 WAT in 1000-and 3000-mM Cs treatments, respectively. Mean values of transfer factors (TFs) in the aboveground parts were 50 mM¼0.78, 150 mM¼1.02, 300 mM¼0.86, 1000 mM¼0.68, and 3000 mM¼0.94, respectively at 7 WAT. Due to its high Cs content and high TF in the aboveground parts, napiergrass may be a candidate plant with high potential for phytoremediation of Cs from Cs-137-contaminated soil.

In this study, the total phenolic and flavonoid contents, the 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging ability and the ferric reducing power (FRAP) of Aloe vera were measured to determine the antioxidant activity of this species. The in vivo antidiabetic effects of the plant were also investigated using streptozotocin-induced type 2 diabetic model rats that were divided into five groups based on the treatment received:

The lipid-lowering action of the leaves of the Aleurites moluccana methanol extract was studied in Triton W-1339 and high-fat-diet fed rats. The serum lipids (total cholesterol, LDL-and HDL-cholesterol and triglycerides) and body weight were found to be lowered by A. moluccana (300 mg/kg, b.w.) in rats with Triton-induced hypercholesterolaemia and on a hyperlipaemic diet. The results suggest that the lipid lowering action of this natural product is mediated through inhibition of hepatic cholesterol biosynthesis and reduction of lipid absorption in the intestine.

We investigated whether the degree of light inhibition of leaf respiration (R) differs among large Eucalyptus saligna grown in whole-tree chambers and exposed to present and future atmospheric [CO2] and summer drought. Associated with month-to-month changes in temperature were concomitant changes in R in the light (Rlight) and darkness (Rdark), with both processes being more temperature dependent in well-watered trees than under drought. Overall rates of Rlight and Rdark were not significantly affected by [CO2]. By contrast, overall rates of Rdark (averaged across both [CO2]) were ca. 25% lower under drought than in well-watered trees. During summer, the degree of light inhibition of leaf R was greater in droughted (ca. 80% inhibition) than well-watered trees (ca. 50% inhibition). Notwithstanding these treatment differences, an overall positive relationship was observed between Rlight and Rdark when data from all months/treatments were combined (R 2 = 0.8). Variations in Rlight were also positively correlated with rates of Rubisco activity and nitrogen concentration. Light inhibition resulted in a marked decrease in the proportion of light-saturated photosynthesis respired (i.e. reduced R/Asat). Collectively, these results highlight the need to account for light inhibition when assessing impacts of global change drivers on the carbon economy of tree canopies.

Maize is a major crop and a model plant for studying C4 photosynthesis and leaf development. However, a genomewide regulatory network of leaf development is not yet available. This knowledge is useful for developing C3 crops to perform C4 photosynthesis for enhanced yields. Here, using 22 transcriptomes of developing maize leaves from dry seeds to 192 h post imbibition, we studied gene up- and down-regulation and functional transition during leaf development and inferred sets of strongly coexpressed genes. More significantly, we developed a method to predict transcription factor binding sites (TFBSs) and their cognate transcription factors (TFs) using genomic sequence and transcriptomic data. The method requires not only evolutionary conservation of candidate TFBSs and sets of strongly coexpressed genes but also that the genes in a gene set share the same Gene Ontology term so that they are involved in the same biological function. In addition, we developed another method to predict...

Leaf senescence is a developmentally and environmentally regulated process which includes global changes in gene expression. Using Arabidopsis as a model, we modified Chl arrangement in photosystems by overexpressing the catalytic domain (the C domain) of chlorophyllide a oxygenase (CAO) fused with the linker domain (the B domain) of CAO and green fluorescent protein (GFP). In these plants (referred to as the BCG plants for the B and C domains of CAO and GFP), the Chl a/b ratio was drastically decreased and Chl b was incorporated into core antenna complexes. The BCG plants exhibited a significant delay of both developmental and dark-induced leaf senescence. The photosynthetic apparatus, CO 2 fixation enzymes and the chloroplast structure were lost in wild-type plants during senescence, while BCG plants retained them longer than the wild type. Large-scale quantitative real-time PCR analyses of 1,880 transcription factor (TF) genes showed that 241 TFs are differentially expressed between BCG plants and wild-type plants at senescence, $40% of which are known senescence-associated genes (SAGs). Expression profiling also revealed the down-regulation of a large number of additional non-TF SAGs. In contrast, genes involved in photosynthesis were up-regulated, while those encoding Chl degradation enzymes were down-regulated in BCG plants. These results demonstrate that alteration of pigment composition in the photosynthetic apparatus retards senescence through transcriptional reprogramming.

There remains conflicting evidence on the relationship between P supply and biological N 2-fixation rates, particularly N 2-fixing plant adaptive strategies under P limitation. This is important, as edaphic conditions inherent to many economically and ecologically important semi-arid leguminous tree species, such as Acacia senegal, are P deficient. Our research objective was to verify N acquisition strategies under phosphorus limitations using isotopic techniques. Acacia senegal var. senegal was cultivated in sand culture with three levels of exponentially supplied phosphorus [low (200 mol of P seedling −1 over 12 weeks), mid (400 mol) and high (600 mol)] to achieve steady-state nutrition over the growth period. Uniform additions of N were also supplied. Plant growth and nutrition were evaluated. Seedlings exhibited significantly greater total biomass under high P supply compared to low P supply. Both P and N content significantly increased with increasing P supply. Similarly, N derived from solution increased with elevated P availability. However, both the number of nodules and the N derived from atmosphere, determined by the 15 N natural abundance method, did not increase along the P gradient. Phosphorus stimulated growth and increased mineral N uptake from solution without affecting the amount of N derived from the atmosphere. We conclude that, under non-limiting N conditions, A. senegal N acquisition strategies change with P supply, with less reliance on N 2-fixation when the rhizosphere achieves a sufficient N uptake zone.

Orange jasmine (Murraya paniculata) leaves were collected from three different sites in the area of Bangkok and in a remote area as a control site. The leaf samples were digested and the concentrations of Cu, Fe, Pb, Mn, Ni, Cr, and Zn were then quantified by using inductively coupled plasma-atomic emission spectrometry (ICP-AES). All three Bangkok sites were polluted with heavy metals compared with the background site. Fe was found as the highest mean concentration of the metals studied, while Pb was the lowest. There was a high correlation coefficient between metals Cu-Mn, Cu-Zn, Cu-Pb, and Mn-Zn. However, Fe was not correlated with other metals. There was no significant difference in Pb between sites. The significant difference in other metals found in the study could be attributed to different anthropogenic activities between sites. The principal-component analysis (PCA) identified two factors according to the sources of metals making up the anthropogenic (traffic) and natural (soil) sources. Traffic emission was found to be the main source of metal pollution in the atmosphere of Bangkok.

Although several strains ofB. subtiliswith antifungal activity have been isolated worldwide, to date there are no published reports regarding the isolation of a nativeB. subtilisstrain from strawberry plants in Mexico. A native bacterium (Bacillus subtilis21) demonstratedin vitroantagonistic activity against different plant pathogenic fungi. Under greenhouse conditions, it was shown that plants infected withRhizoctonia solaniandFusarium verticillioidesand treated withB. subtilis21 produced augment in the number of leaves per plant and an increment in the length of healthy leaves in comparison with untreated plants. In addition,B. subtilis21 showed activity against pathogenic bacteria. Secreted proteins byB. subtilis21 were studied, detecting the presence of proteases and bacteriocin-like inhibitor substances that could be implicated in its antagonistic activity. Chitinases and zwittermicin production could not be detected. Then,B. subtilis21 could potentially be used to control phyt...

The process of dark-induced senescence in plants is relatively poorly understood, but a functional electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase (ETF/ETFQO) complex, which supports respiration during carbon starvation, has recently been identified. Here, we studied the responses of Arabidopsis thaliana mutants deficient in the expression of isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase to extended darkness and other environmental stresses. Evaluations of the mutant phenotypes following carbon starvation induced by extended darkness identify similarities to those exhibited by mutants of the ETF/ETFQO complex. Metabolic profiling and isotope tracer experimentation revealed that isovaleryl-CoA dehydrogenase is involved in degradation of the branched-chain amino acids, phytol, and Lys, while 2-hydroxyglutarate dehydrogenase is involved exclusively in Lys degradation. These results suggest that isovaleryl-CoA dehydrogenase is ...

Four orange-pigmented isolates, L7-456, L7-484T, L9-479 and L9-753T, originating from surface-sterilized leaf tissues of Jatropha curcas L. cultivars were characterized using a polyphasic taxonomic approach. Phylogenetic analyses based on 16S rRNA gene sequences indicated that all four isolates belong to the genus Aureimonas . In these analyses, strain L7-484T appeared to be most closely related to Aureimonas ureilytica 5715S-12T (95.7 % sequence identity). The 16S rRNA gene sequences of strains L7-456, L9-479 and L9-753T were found to be identical and also shared the highest similarity with A. ureilytica 5715S-12T (97.5 %). Both L7-484T and L9-753T contained Q-10 and Q-9 as predominant ubiquinones and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidyldimethylethanolamine, sulfoquinovosyldiacylglycerol and an aminophospholipid as the major polar lipids. C18 : 1ω7c and C16 : 0 were the major fa...

A new γ-lactone coumarin, named as excavarin-A, showing antifungal activity was isolated from the leaves of Clausena excavata by bioassay guided fractionation method. The structure was elucidated by spectroscopic data analysis and identified as 7((2E)-4(4,5-dihydro-3-methylene-2-oxo-5-furanyl)-3-methylbut-2-enyloxy) coumarin. Minimum inhibitory concentration (MIC) was determined against fifteen fungal strains pathogenic against plants and human. The least MIC was recorded against the human pathogen, Candida tropicalis and the plant pathogens Rhizoctonia solani and Sclerotinia sclerotiorum. Antifungal activities against the human pathogens, Aspergillus fumigatus and Mucor circinelloides and plant pathogens, Colletotrichum gloeosporioides, Lasiodiplodia theobromae, Fusarium oxysporum and Rhizopus stolonifer were stronger than that of the standard antimicrobials.

Rhus succedanea is generally traded, distributed and sold in the markets in its crude and raw form. This may have been mixed with adulterants, mismanaged by malpractices and substituted with other closely related drugs having different effect. This study is therefore carried out to authenticate the plant through pharmacogonostic evaluations. The organoleptic studies were carried through sensory organs i.e size, shape, texrure, odour, etc. Histological studies were conducted by preparing hand slides, mounting the specimen in potato tuber; fluorescence characters were determined through UV and phytochemical screening was investigated using various standard and common methods from relevant literature. Morphologically, the Rhus is a perennial small sized deciduous tree, 5-9 m tall with opposite imparipinnately compound leaves and small grayish yellow flowers born on paniculate inflorescence; locally, called as Rakhkal in Pashto and Kakarsingi in Urdu. The organoleptic evaluation showed ...

Rust fungi are devastating plant pathogens and several Puccinia species have a large economic impact on wheat production worldwide. Disease protection, mostly offered by introgressed host-resistance genes, is often racespecific and rapidly overcome by newly-emerging virulent strains. Extensive new genomic resources have identified vital pathogenicity genes but their study is hampered because of the biotrophic life styles of rust fungi. In cereals, Barley stripe mosaic virus (BSMV)-induced RNAi has emerged as a useful tool to study loss-of-function phenotypes of candidate genes. Expression of pathogenderived gene fragments in this system can be used to obtain in planta-generated silencing of corresponding genes inside biotrophic pathogens, a technique termed host-induced gene silencing (HIGS). Here we test the effectiveness of BSMV-mediated HIGS in the wheat leaf rust fungus Puccinia triticina (Pt) by targeting three predicted pathogenicity genes, a MAPK, a cyclophilin, and a calcineurin regulatory subunit. Inoculation of BSMV RNAi constructs generated fungal gene-specific siRNA molecules in systemic leaves of wheat plant. Subsequent Pt inoculation resulted in a suppressed disease phenotype and a reduction in endogenous transcript levels of the targeted fungal genes indicating translocation of siRNA molecules from host to fungal cells. Efficiency of this host-generated trans-specific RNAi was enhanced by using BSMV silencing vectors defective in coat protein coupled with introducing fungal gene sequences simultaneously in sense and antisense orientation. The disease suppression indicated the likely involvement of these fungal genes in pathogenicity. This study demonstrates that BSMV-mediated in planta-generated RNAi is an effective strategy for functional genomics in rust fungi.

The classical definition of mesophyll conductance (g m) represents an apparent parameter (g m,app) as it places (photo)respired CO2 at the same compartment where the carboxylation by Rubisco takes place. Recently, Tholen and co-workers developed a framework, in which g m better describes a physical diffusional parameter (g m,dif). They partitioned mesophyll resistance (r m,dif = 1/g m,dif) into two components, cell wall and plasmalemma resistance (r wp) and chloroplast resistance (r ch), and showed that g m,app is sensitive to the ratio of photorespiratory (F) and respiratory (R d) CO2 release to net CO2 uptake (A): g m,app = g m,dif/[1 + ω(F + R d)/A], where ω is the fraction of r ch in r m,dif. We herein extend the framework further by considering various scenarios for the intracellular arrangement of chloroplasts and mitochondria. We show that the formula of Tholen et al. implies either that mitochondria, where (photo)respired CO2 is released, locate between the plasmalemma and t...

In the present study, a minicolumn of sisal fiber loaded with alizarin fluorine blue is proposed as a preconcentratio system for copper determination in tobacco leaf samples by flame atomic absorption spectrometry. During the optimization procedure, a two level full factorial design (2 4 ) was used at the preliminary evaluation of four factors, involving the following variables: sampling flow rate, elution flow rate, buffer concentration and pH. Regarding the studied levels, this design has shown that buffer concentration and pH were significant factors. The experimental conditions established in the optimization step were: pH = 4.75, buffer concentration of 0.005 mol L −1 for elution with HCl 1.0 mol L −1 this system allows the determination of copper content with a detection limit (LD) of 0.018 g L −1 and a quantification limit (LQ) of 0.061 g L −1 precision expressed as relative standard deviation (R.S.D.) of 4.65 and 5.07%, utilizing concentration of 10 and 2.0 g L −1 , respectively, and a preconcentratio factor of 75, for a sample volume of 50.0 mL. Accuracy was confirmed by copper determination in the standard reference material, NIST SRM 1570a trace element units in Spinach Leaves and by spike tests with recovery levels ranging from 93 to 100%; the procedure was applied for copper determination in tobacco leaf samples collected in Cruz das Almas City, Bahia, Brazil. The achieved concentrations of the three samples analyzed varied from 0.15 to 0.52 g g −1 .

The cytotoxic effects of seven constituents isolated from Duguetia glabriuscula were evaluated against Hep 2 human larynx carcinoma cells. The cytotoxicity exhibited by β-sitosterol was as strong as that of cis-platin. (+)-Alloaromadendran-10,14β-diol caused inhibition of cellular growth with IC 50 values lower than 25 μg/ml, a feature that was considered as revealing significant activity. Polycarpol showed borderline cytotoxicity, whereas the other compounds were inactive.

Le septembre 2008 Titre : Caractérisation moléculaire et physiologique des Facteurs de Réponse à l'Ethylène (ERF) chez la tomate (Solanum lycopersicon) JURY Mr. Jean-Claude PECH Président (INP-ENSAT) Mr. Christophe ROTHAN Rapporteur (INRA Bordeaux) Mr. Guy ALBAGNAC Rapporteur (INRA Montpellier) Mme. Mathilde CAUSSE Examinatrice (INRA Avignon) Mr. Masaru OHME-TAKAGI Examinateur (AIST Tsukuba) Mr. Farid REGAD Examinateur (INP-ENSAT) Mr. Mondher BOUZAYEN Directeur de thèse (INP-ENSAT) Mr. Xavier BERTHET Membre invité (NINSAR Barcelone) Ecole doctorale : Biologie Santé et Biotechnologie Unité de recherche : UMR990 INP-ENSAT/INRA Génomique et Biotechnologie des Fruits Directeur de Thèse : Pr. Mondher BOUZAYEN Je remercie Mondher BOUZ AYEN et Masaru OHME-T AKAGI pour m'avoir acceuilli, encadré et fait confiance pendant ce travail de thèse. Je remercie Farid REGAD pour les discussions scientifiques ainsi que son soutien jusqu'à très tard dans la nuit. Je remercie Jean-Claude PECH et Alain LATCHE pour avoir échangé scientifiquement avec moi. Un merci tout spéciale à Corinne, Isabelle, Simone, Marie, Salma et Benoît pour tous les moments de sciences (ou pas) partagés. Merci à Prassad, Ravi, Wangshu et Lanlan d'avoir participé à cette aventure. Un grand merci à Hélène, Carole, Lydie, Olivie r et Dominique pour la transformation et le suivi des plantes transgéniques (et ce n'est pas peu dire). Un grand merci à l'ensemble des membres du laboratoire pour tous les moments partagés, de sciences, et de convivialité : Christian, Je tiens également à remercier tous les membres du Research Institute of Genome-based Biofactory Miho Ikeda, Akira Iwase, Yoshimi Umemura, Tomotsugu Koyama, Masahito Shikata, Kyoko Matsui, Nobut aka Mitsuda, Naoko Kaneta , sans qui cette thèse n'aurait pas eu le même parfum. ありがとう. Merci aussi à Toshi et Hiroshi Ez ura de m'avoir acceuilli. Merci à mes proches qui m'ont soutenu pendant ces années, mes parents et mon frère. Enfin, je tiens à remercier tout particulièrement Laëtitia qui m'a suivi au bout du monde (au sens propre et au sens figuré), pour son soutien permanent et sans qui ce travail aurait été un peu différent. (2007): Isolation and characterization of a Vitis vinifera transcription factor, VvWRKY1, and its effect on responses to fungal pathogens in transgenic tobacco plants J Exp Bot.;58 (8):

The colonization of apple blossoms and leaves by Pseudomonas fluorescens EPS62e was monitored in greenhouse and field trials using cultivable cell counting and real-time PCR. The real-time PCR provided a specific quantitative method for the detection of strain EPS62e. The detection level was around 10 2 cells g (fresh weight) ؊1 and the standard curve was linear within a 5-log range. EPS62e actively colonized flowers reaching values from 10 7 to 10 8 cells per blossom. In apple flowers, no significant differences were observed between population levels obtained by real-time PCR and plating, suggesting that viable but nonculturable (VBNC) cells and residual nondegraded DNA were not present. In contrast, on apple leaves, where cultivable populations of EPS62e decreased with time, significant differences were observed between real-time PCR and plating. These differences indicate the presence of VBNC cells or nondegraded DNA after cell death. Therefore, the EPS62e population was under optimal conditions during the colonization of flowers but it was stressed and poorly survived on leaves. It was concluded that for monitoring this biological control agent, the combined use of cultivable cell count and real-time PCR is necessary.

Optimum growth temperature rpb2 28S rRNA tub1 Volatile metabolites a b s t r a c t The fungal genus Muscodor was erected on the basis of Muscodor albus, an endophytic fungus originally isolated from Cinnamomum zeylanicum. It produces a mixture of volatile organic compounds (VOCs) with antimicrobial activity that can be used as mycofumigants.

Methanol and dichloromethanol extracts of the leaves and stems of Teucrium cartaginenses L. have been tested for their effects on resting arterial blood pressure, heart rate and noradrenaline induced hypertension. Both extracts administered i.v. to urethane anaesthetized normotensive rats reduced mean arterial blood pressure and heart valve, while only the dichloromethanol extract prevented noradrenaline induced hypertension.

Oxygen atoms in plant products originate from CO 2 , H 2 O and O 2 , precursors with quite dierent 18 O values. Furthermore their incorporation by dierent reactions implies isotope eects. On this base the resulting non-statistical 18 O distributions in natural compounds are discussed. The 18 O value of cellulose is correlated to that of the leaf water, and the observed 18 O enrichment ($+27%) is generally attributed to an equilibrium isotope eect between carbonyl groups and water. However, as soluble and heterotrophically synthezised carbohydrates show other correlations, a non-statistical 18 O distribution Ð originating from individual biosynthetic reactions Ð is postulated for carbohydrates. Similarly, the 18 O values of organic acids, carbonyl compounds, alcohols and esters indicate water-correlated, but individual 18 O abundances (e.g. O from acyl groups $+19% above water), depending upon origin and biosyntheses. Alcoholic groups introduced by monooxygenase reactions, e.g. in sterols and phenols, show 18 O values near +5%, in agreement with an assumed isotope fractionation factor of $1.02 on the reaction with atmospheric oxygen ( 18 O=+23.5%). Correspondingly, a``thermodynamically ordered isotope distribution'' is only observed for oxygen in some functional groups correlated to an origin from CO 2 and H 2 O, not from O 2 . The individual isotopic increments of functional groups permit the prediction of global 18 O values of natural compounds on the basis of their biosynthesis. #