Plant Growth–Promoting Pseudomonas sp. Strains Reduce Natural Occurrence of Anthracnose in Soybean (Glycine max L.) in Central Himalayan Region

Biological control is an accepted important component of current plant disease management strategies. Introduction of bacterized seeds carrying bacterial isolates with proven growth-promotion capabilities and antagonistic characteristics offer a valid alternative to chemical protectants. Root colonization of disease-susceptible (PS 1024) and moderately resistant (PS1042) varieties of soyabean (Glycine Max L) by fluorescent pseudomonad (FLPs) strains GRP₃, PEn-4, PRS₁, and WRS-24 was studied in relation to natural occurrence of anthracnose caused by Colletotrichum dematium (Pers Ex Fr.) Grove. Rhizoplane population of FLPs was maintained at a critical level (5.3 cfu) up to 30 days of plant growth, followed by a steep decline. Indigenous FLPs population, however, remained nearly unchanged (3.0 to 2.4 log g⁻¹ root) between 30 days and 75 days of plant growth. The relative FLPs population in rhizosphere was lower than that in rhizoplane. Although intervarietal difference was observed, the root/shoot length remained unaffected. Compared to nonbacterized control, dry root weight was improved by FLPs treatment. Severity of foliar anthracnose was reduced significantly after FLPs treatment in the variety PS 1042. Because the point of FLPs treatment (seed bacterization) was away from the site of disease appearance (leaf), operation of induced systemic resistance in strains PEn-4 and GRP₃ appears imminent.     

Induction of Plant Defense Enzymes and Phenolics by Treatment With Plant Growth–Promoting Rhizobacteria Serratia marcescens NBRI1213

In greenhouse experiments, plant growth–promoting rhizobacteria (PGPR) Serratia marcescens NBRI1213 was evaluated for plant growth promotion and biologic control of foot and root rot of betelvine caused by Phytophthora nicotianae. Bacterization of betelvine (Piper betle L.) cuttings with S. marcescens NBRI1213 induced phenylalanine ammonia-lyase, peroxidase, and polyphenoloxidase activities in leaf and root. Qualitative and quantitative estimation of phenolic compounds was done through high-performance liquid chromatography (HPLC) in leaf and root of betelvine after treatment with S. marcescens NBRI1213 and infection by P. nicotianae. Major phenolics detected were gallic, protocatechuic, chlorogenic, caffeic, ferulic, and ellagic acids by comparison of their retention time with standards through HPLC. In all of the treated plants, synthesis of phenolic compounds was enhanced compared with control. Maximum accumulation of phenolics was increased in S. marcescens NBRI1213–treated plants infected with P. nicotianae. In a greenhouse test, bacterization using S. marcescens NBRI1213 decreased the number of diseased plants compared with nonbacterized controls. There were significant growth increases in shoot length, shoot dry weight, root length, and root dry weight, averaging 81%, 68%, 152%, and 290%, respectively, greater than untreated controls. This is the first report of PGPR–mediated induction of phenolics for biologic control and their probable role in protecting betelvine against P. nicotianae, an important soil-borne phytopathogenic fungus.     

Bioremediation of Cadmium-Contaminated Soil through Cultivation of Maize Inoculated with Plant Growth–Promoting Rhizobacteria

A pot experiment was conducted to study the effect of single and co-inoculation of Bacillus mycoides and Micrococcus roseus strains, indigenous to heavy metal (HM)–contaminated soils, on the growth and essential-nutrient and Cd uptake of maize in a soil polluted with 100 and 200 mg Cd kg^?1. Increasing Cd levels significantly decreased shoot and root dry weights, and shoot P, Fe, Zn, and Mn uptake. All bacterial treatments significantly increased biomass and shoot nutrient uptake of plant compared with control in the soil polluted with Cd. Inoculation of plants with B. mycoides and consortium of two bacteria significantly increased, whereas M. roseus significantly decreased, shoot and root Cd uptake, and Cd transfer and translocation factors compared with control in Cd-polluted conditions. The results showed that B. mycoides and consortium of two bacteria had an effective role in phytoextraction and M. roseus was the most effective treatment in phytostabilization of Cd.     

Population structure and marker�Ctrait association analysis of the US peanut (Arachis hypogaea L.) mini-core collection

Peanut (Arachis hypogaea L.) is one of the most important oilseed and nutritional crops in the world. To efficiently utilize the germplasm collection, a peanut mini-core containing 112 accessions was established in the United States. To determine the population structure and its impact on marker-trait association, this mini-core collection was assessed by genotyping 94 accessions with 81 SSR markers and two functional SNP markers from fatty acid desaturase 2 (FAD2). Seed quality traits (including oil content, fatty acid composition, flavonoids, and resveratrol) were obtained through nuclear magnetic resonance (NMR), gas chromatography (GC), and high-performance liquid chromatography (HPLC) analysis. Genetic diversity and population structure analysis identified four major subpopulations that are related to four botanical varieties. Model comparison with different levels of population structure and kinship control was conducted for each trait and association analyses with the selected models verified that the functional SNP from the FAD2A gene is significantly associated with oleic acid (C18:1), linoleic acid (C18:2), and oleic-to-linoleic (O/L) ratio across this diverse collection. Even though the allele distribution of FAD2A was structured among the four subpopulations, the effect of FAD2A gene remained significant after controlling population structure and had a likelihood-ratio-based R ( 2 ) (R ( LR ) ( 2 ) ) value of 0.05 (oleic acid), 0.09 (linoleic acid), and 0.07 (O/L ratio) because the FAD2A alleles were not completely fixed within subpopulations. Our genetic analysis demonstrated that this peanut mini-core panel is suitable for association mapping. Phenotypic characterization for seed quality traits and association testing of the functional SNP from FAD2A gene provided information for further breeding and genetic research.     

高油酸花生(Arachis hypogaea L.)杂交后代ahFAD2B基因的分子标记辅助选择

本研究利用等位基因特异性PCR技术(AS-PCR,allele-specific PCR)对高油酸父本CTWE与4个低油酸母本组配的330个杂交后代进行分子鉴评,其中230个获得了539 bp的特异性条带。白沙1016×CTWE、海花1号×CTWE、冀0212-2×CTWE以及远杂9847×CTWE的真杂种百分率分别为83.3%、50.0%、57.1%和50.0%。本研究采用单粒近红外光谱分析法对F2:3家系进行检测,结果表明远杂9847×CTWE、白沙1016×CTWE、冀0212-2×CTWE以及海花1号×CTWE的F2:3家系中,全部为高油酸类型的家系分别为9个、8个、2个和3个,推断F2群体中,基因型为FAD2B-m/FAD2B-m的个体的比例为9.47%、4.17%、3.39%和3.37%。4个杂交组合高油酸性状的遗传在P=0.05水平上符合2对基因的遗传模式。本研究结果对于高油酸性状的分子鉴定、高油酸花生新品种的培育以及育种效率的提高具有一定的参考价值。     

Isolation and Phenotypic Characterization of Plant Growth–Promoting Rhizobacteria with High Antiphytopathogenic Activity and Root-Colonizing Ability

Some bacterial strains isolated from the plant rhizosphere showed high root-colonizing ability and antiphytopathogenic activity against 6 fungal species. The antifungal activity was species-specific, which could be accounted for by the fact that the isolates differed in the ability to produce lytic enzymes (chitinases, proteases, and lipases) and to secrete cyanide. The possibility of using there rhizobacteria to control phytopathogens is discussed.     

Characterization of a Novel Cr6+ Reducing Pseudomonas sp. with Plant Growth–Promoting Potential

The isolate RNP4 obtained from a long-term tannery waste contaminated soil was characterized and presumptively identified as Pseudomonas sp. The strain RNP4 tolerated concentrations up to 450 mg Cr⁶⁺/L on a Luria-Bartani (LB) agar medium and reduced a substantial amount of Cr⁶⁺ to Cr³⁺ in the LB liquid medium. The ability of performing multifarious activities in tandem suggested the uniqueness of isolate RNP4. The strain produced a substantial amount of indole acetic acid (IAA) in tryptophan-supplemented medium. The strain also exhibited the production of siderophore and solubilization of phosphorus in mineral salt medium and SRS1 medium, respectively. Concurrent production of IAA and siderophore and the solubilization of phosphorus revealed its plant growth promotion potential. Furthermore, the strain was able to promote the growth of black gram, Indian mustard, and pearl millet in the presence of Cr⁶⁺. Thus, the innate capability of this novel isolate for parallel bioremediation and plant growth promotion has significance in the management of environmental and agricultural problems.     

Production of eicosapentaenoic acid (EPA, 20:5n-3) in transgenic peanut (Arachis hypogaea L.) through the alternative Δ8-desaturase pathway

Molecular Biology Reports - An important alternative source of fish oil is its production by plants through metabolic engineering. To produce eicosapentaenoic acid (EPA, 20:5n-3) in peanut through...     

Silicon Enhances Morpho–Physio–Biochemical Responses in Arsenic Stressed Spinach (Spinacia oleracea L.) by Minimizing Its Uptake

Journal of Plant Growth Regulation - Soil contamination with toxic heavy metals [such as arsenic (As)] is becoming a serious global problem due to rapid development of social economy. Silicon (Si),...     

Ambrosia elatior (L.) in Hungary (1989–1990)

Summary Weeds and among themAmbrosia are probably the most important vascular plants related to pollinosis in Hungary. Sampling was carried out in central (Budapest) and in southern (Paks, Szeged) Hungary. The results of two years (1989–1990) of aerobiological study onAmbrosia airborne pollen are reported. The highest percentage of airborne pollen was found in the mid-August to mid-September period, having a good correlation with clinical data on pollinosis. The implications of these results are considered in the context of forecasting and prevention of seasonal ragweed pollinosis.     

Isolation and characterization of the Δ12-fatty acid desaturase in peanut (Arachis hypogaea L.) and search for polymorphisms for the high oleate trait in Spanish market-type lines

An understanding of the molecular mechanisms that are responsible for increased oleic acid accumulation would open avenues to alter peanut fatty acid composition and allow detection of polymorphic regions which can be used for marker assisted selection (MAS). Δ¹²-Fatty acid desaturase (FAD) was isolated and characterized from genotypes having a low or high oleic to linoleic acid O/L ratio – genotypes, Tamspan 90 (T-90) and F435–2-2 (F435), respectively. Southern blots showed three to four copies per haploid genome, and no major differences in organization between the two parental lines. Approximately 3525 bp was isolated from both genotypes, including a genomic walk toward the promoter region. The Δ¹²-Fad contains a putative intron, the coding region at the 3′ end, and an open reading frame (ORF) of 1140 bp encoding 379 amino acids. Comparisons of the coding sequences from the high and low oleic acid genotypes revealed several single nucleotide polymorphisms (SNPs). Two polymorphisms appear to be associated with the high O/L trait. The first is an ”A” insertion 442 bp after the start codon. The ”A” insertion shifts the amino acid reading frame, probably resulting in a truncated, inactive protein and the loss of one of three histidine boxes believed to be involved in metal ion complexation required for the reduction of oxygen. Another polymorphism at 448 bp from the start codon results in an amino acid change. The region containing the polymorphisms was amplified from leaf tissue of several independently derived backcross lines (IDBLs). Most high O/L lines had either the ”A” insertion or the amino acid substitution. Received: 1 February 2000 / Accepted: 20 March 2000     

Augmented Phytoextraction of Lead (Pb2+)-Polluted Soils: A Comparative Study of the Effectiveness of Plant Growth Regulators,EDTA, and Plant Growth–Promoting Rhizobacteria

Abstract

The role of gibberellic acid (GA3), indole-3-acetic acid (IAA), plant growth–promoting bacteria (Rhizobium and Azotobacter), and a synthetic chelator (EDTA; ethylenediaminetetraacetic acid) in lead (Pb) phytoextraction was evaluated using Parthenium hysterophorus (dicot, unpalatable noncrop) and Zea mays (monocot food/forage crop) plants at the flowering stage. Various plant parts were analyzed by atomic absorption/flame spectrophotometer for their Pb content. Both plant growth regulators and both growth-promoting bacteria significantly increased the plant growth in Pb-polluted soils, whereas EDTA significantly decreased growth and biomass of both plants. EDTA increased the Pb uptake (μg g^?1 dry biomass), but the total plant Pb accumulation was decreased. GA3 and IAA significantly increased both uptake and translocation, and the maximum total Pb in the entire plant of Parthenium was found with GA3 foliar spray, whereas in Z. mays the total Pb was maximum in the plant treated with GA3 in combination with EDTA, followed by the GA3 foliar spray treatment. Overall, the GA3 foliar application showed superior response compared with all other treatments. Further research is recommended to observe the role of endogenous GA3 levels in correlation with metal phytoextraction in different plants.     

Iron-Deficiency Stress Responses in Cucumber (Cucumis sativus L.) Roots (A Possible Role for Ethylene?)

Most dicotyledonous species respond to Fe deficiency by developing several mechanisms known as Fe-deficiency stress responses. To study the regulation of these responses, young cucumber plants (Cucumis sativus L. cv Ashley) were grown in nutrient solution for 11 d, being deprived of Fe during the last 4 or 5 d. Inhibitors of ethylene synthesis (2 or 10 [mu]M aminoethoxyvinylglycine; 10 or 20 [mu]M aminooxyacetic acid; 1, 2, 5, or 10 [mu]M Co2+ as CoCl2) or action (50, 200, or 800 [mu]M Ag+ as silver thiosulfate) were added to the nutrient solution at different times during this period of growth with no Fe. After this period, the reduction of Fe3+ ethylenedi-aminetetraacetate by the roots of entire plants was measured with ferrozine by reading the absorbance at 562 nm after 2 h. The presence of the ethylene inhibitors in the nutrient solution inhibited the Fe-deficiency stress responses ferric-reducing capacity and subapical root swelling. In another experiment, the addition of 1 [mu]M 1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ethylene synthesis, to the nutrient solution of plants having low ferric-reducing activity increased notably the ferric-reducing capacity and subapical root swelling. Here we show evidence that ethylene plays a role in the development of Fe-deficiency stress responses, since when ethylene synthesis or action was inhibited, the responses were also inhibited, and when a precursor of ethylene (ACC) was added, the responses were increased.     

Inheritance of Organelle DNA in Rye (Secale cereale L.) with Triticale (×Triticale Thch.) Hybrids

The mode of inheritance of chloroplast and mitochondrial DNA (mtDNA) in rye × triticale intergeneric hybrids has been studied with the use of specific PCR markers for loci 18S/5S and 3rbcL in organelle DNA. In rye × triticale BC₁, mtDNA copies of two types, paternal and maternal, have been found; in BC₂ plants, only paternal mtDNA and chloroplast DNA (cpDNA) have been detected. Mechanisms determining the inheritance and/or differential amplification of organelles of a specific type are discussed.     

Subcellular Localization and Possible Functions of γ-Glutamyltransferase in the Radish (Raphanus sativus L.) Plant

Previously we reported the purification of soluble γ-glutamyltransferases (GGTs) from radish cotyledon. Subcellular fractionation of radish cells revealed that soluble GGT is a vacuolar enzyme. Acivicin, a GGT inhibitor, mediated the in vivo catabolism inhibition of the glutathione S-conjugate generated from endogenous glutathione and exogenously supplied monochlorobimane. Thus soluble GGT is possibly involved in the catabolism of glutathione S-conjugates.     

Plant–Microbe Interactions: Wetting of Ivy (Hedera helix L.) Leaf Surfaces in Relation to Colonization by Epiphytic Microorganisms

Abstract Leaf wettability, cuticular wax composition, and microbial colonization of upper and lower leaf surfaces of ivy (Hedera helix L.) was investigated for young and old leaves sampled in June and September. Contact angles of aqueous buffered solutions measured on young leaf surfaces ranged between 76° and 86° and were not dependent on the pH value of the applied droplets. Contact angles measured on old leaf surfaces were up to 32°, significantly lower than on young leaf surfaces. Furthermore, contact angles were significantly lower using aqueous solutions of pH 9.0 compared to pH 3.0, indicating the influence of ionizable functional groups on leaf surface wetting properties. Observed changes in leaf wetting properties did not correlate with different levels of alkanoic acids in cuticular waxes. However, microscopic examination of the leaf surfaces indicated the influence of epiphytic microorganisms on wetting properties of old leaves, since their surfaces were always colonized by epiphytic microorganisms (filamentous fungi, yeasts, and bacteria), whereas surfaces of young leaves were basically clean. In order to analyze the effect of epiphytic microorganisms on leaf surface wetting, surfaces of young and clean ivy leaves were artificially colonized with Pseudomonas fluorescens. This resulted in a significant increase and a pH dependence of leaf surface wetting in the same way as it was observed on old ivy leaf surfaces. From these results it can be deduced that the native wetting properties of leaf surfaces can be significantly masked by the presence of epiphytic microorganisms. The ecological implications of altered wetting properties for microorganisms using the leaf/atmosphere interface as habitat are discussed. Received: 20 March 1999; Accepted: 5 July 1999; Online Publication: 18 July 2000     

Changes in behaviour associated with pair formation in the polychaete Harmothoë imbricata (L.)

Spacing between individuals in populations of Harmothoë imbricata has been investigated both on the shore and in the laboratory. Males tend to occur closer together than females, and the mean male‐male individual distance measured was less than the mean distance between females; male—female distances for immature worms were intermediate. When worms mature they pair: the male mounts the female and lies across her dorsal surface. There is evidence that after spawning the members of a pair separate. Contact responses between worms have been investigated in the laboratory. Most encounters between immature worms lead to separation, as a result of one or both worms moving rapidly away from the other or fighting; females show more marked avoidance behaviour than males. The majority of male‐male and female‐female encounters between mature worms also lead to separation but in male‐female encounters the male usually mounts the female. A male which has mounted a female becomes highly aggressive and will attack intruding males but not females.     

Growth,photosynthesis and transpiration in Psophocarpus tetragonolobus (L.) DC cultivar ‘UPS 99’

Two methods (whole-plant growth analysis and gas exchange) were used to measure the response of Psophocarpus tetragonolobus (L.) DC cultivar UPS 99 to the environment. This plant had an optimal temperature for root growth of 25°C, its rate of acetylene reduction (when inoculated with Rhizobium, strain RRIM 56) was maximal at 30°C and it required an atmospheric temperature of about 35°C for optimal shoot growth. Maximum water-use efficiency was ca. 33 mg CO₂·g H₂O^-1. The rate of photosynthesis reached a plateau at 900 vpm CO₂-this condition also gave the lowest rate of transpiration. Under normal conditions, the light compensation point was at 1.7 klx, while that for CO₂ was 60 vpm. Photorespiration diminished gross photosynthesis of P. tetragonolobus by forty percent. Water stress (as measured by sensitivity to slightly increased CO₂ levels) caused rapid closure of stomata, and the response was remembered for up to five days.

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Zusammenfassung Mit Hilfe von zwei Methoden (Wachstumsanalysen ganzer Pflanzen und Gaswechselmessungen) wurde die Reaktion von Psophocarpus tetragonolobus (L.) DC der Sorte UPS 99 auf Umwelteinflüsse ermittelt. 25°C war die optimale Temperatur für das Wurzelwachstum. Die Acetylenreduktionsrate (die Pflanzen waren geimpft worden mit Rhizobium RRIM 56) war am höchsten bei 30°C. 35°C waren notwendig für maximales Sproßwachstum. Der günstigste Wasserausnutzungskoeffizient lag bei ungefähr 33 (mg CO₂·g H₂O^-1). Die Photosyntheseraten wurden durch Erhöhung der CO₂-Konzentration gesteigert. Bei Konzentrationen über 900 vpm CO₂ konnte allerdings keine weitere Steigerung mehr festgestellt werden. Bei 900 vpm CO₂ waren die Transpirationsraten am niedrigsten. Unter normalen Bedingungen stellte sich der Lichtkompensationspunkt bei 1,7 klx ein. Der CO₂-Kompensationspunkt lag bei 60 vpm CO₂. Die Photorespiration verminderte die Photosynthese von P. tetragonolobus um 40%. Wasserstreß vergrößerte die Empfindlichkeit der Stomata gegenüber etwas erhöhten CO₂-Konzentrationen (die Stomata schließen). Diese Empfindlichkeit war bis zu 5 Tagen nach der Streßbehandlung noch meßbar.

     

Pollen–pistil interaction in protogyny and self-incompatibility system of Indian mustard (Brassica juncea (L.) Coss.)

The pollen morphology of two species of Drosera has been investigated by means of both light and electron microscopy. The apertures are situated proximally, a state rarely found in the pollen of Angiospermous plants. The pollen morphology of Aldrovanda, Dionea and Drosophyllum is compared.     

Glu–Phe from onion (Allium Cepa L.) attenuates lipogenesis in hepatocytes

A Glu–Phe (EF) was isolated from onion (Allium cepa L. cv. Sunpower). The chemical structure of EF was determined by nuclear magnetic resonance and electrospray ionization–mass (ESI?MS) spectroscopy. We showed that EF reduced lipid accumulation in mouse hepatocytes by inhibiting the expression of sterol regulatory element-binding protein-1c (SREBP–1c) and its lipogenic target genes. We also found that AMP-activated protein kinase (AMPK) was required for the inhibitory effect of EF on lipid accumulation in mouse hepatocytes. Furthermore, EF was qualified in nine onion cultivars by selective multiple reaction-monitoring detection of liquid chromatography–ESI?MS. These results suggest that EF could contribute to the beneficial effect of onion supplement in maintaining hepatic lipid homeostasis.