Plant defense against leaf herbivory based on metal accumulation: examples from a tropical high altitude ecosystem

Species that evolved in high‐altitude grasslands, where soils are dystrophic and metal rich, developed adaptations for these extreme conditions, such as metal accumulation and sclerophyllous leaves, and these adaptations may secondarily affect insect herbivory activity. The present study investigates the hypothesis that costs related to accumulation of certain metals may be evolutionarily compensated for by decreasing leaf herbivory in some plant species from rupestrian fields. Studies were conducted in different locations at the Ferriferous Quadrangle, a metal‐rich region in south‐east Brazil, with four species adapted to high‐altitude grasslands: Eremanthus erythropappus, Eremanthus incanus, Lychnophora ericoides and Byrsonima variabilis. Sample design varied according to population sizes and spatial distribution of individuals. We found that concentrations of manganese (Mn) and iron (Fe) significantly reduced the herbivory in the leaves of E. erythroppapus and E. incanus, whereas aluminum (Al) reduced herbivory in L. ericoides, and Mn affected negatively the herbivory in B. variabilis. These results support the hypothesis that metal‐accumulating plants, as a response to the harsh environment in which they evolved, are protected against foliar damage caused by insect herbivores in rupestrian fields.     

Effects of invasive species on plant communities: an example using submersed aquatic plants at the regional scale

Submersed aquatic plants have a key role in maintaining functioning aquatic ecosystems through their effects on the hydrological regime, sedimentation, nutrient cycling and habitat of associated fauna. Modifications of aquatic plant communities, for example through the introduction of invasive species, can alter these functions. In the Sacramento-San Joaquin River Delta, California, a major invasive submersed plant, Brazilian waterweed Egeria densa, has become widespread and greatly affected the functionality of the submersed aquatic plant community. Rapid assessments of the distribution and abundance of this species are therefore crucial to direct management actions early in the season. Given the E. densa bimodal growth pattern (late spring and fall growth peaks), summer assessments of this species may indicate which and where other submersed species may occur and fall assessments may indicate where this and other species may occur in the following spring, primarily because the Delta’s winter water temperatures are usually insufficient to kill submersed aquatic plant species. We assessed community composition and distribution in the fall of 2007 and summer of 2008 using geostatistical analysis; and measured summer biomass, temperature, pH, salinity, and turbidity. In the fall of 2007, submersed aquatic plants covered a much higher proportion of the waterways (60.7%) than in the summer of 2008 (37.4%), with a significant overlap between the seasonal distribution of native and non-native species. Most patches were monospecific, and multispecies patches had significantly higher dominance by E. densa, co-occurring especially with Ceratophyllum demersum. As species richness of non-natives increased there was a significant decrease in richness of natives, and of native biomass. Sustained E. densa summer biomass negatively affected the likelihood of presence of Myriophyllum spicatum, Potamogeton crispus, and Elodea canadensis but not their biomass within patches. Depth, temperature and salinity were associated with biomass; however, the direction of the effect was species specific. Our results suggest that despite native and invasive non-native submersed plant species sharing available niches in the Delta, E. densa affects aquatic plant community structure and composition by facilitating persistence of some species and reducing the likelihood of establishment of other species. Successful management of this species may therefore facilitate shifts in existing non-native or native plant species.     

THE ROLE OF ROOTS IN THE NUTRITION OF AQUATIC VASCULAR PLANTS

Rooted stems of three aquatic species were cultured in a two-compartment apparatus which allowed the upper and lower portions of the stem to be kept in different nutrient solutions. P³² was supplied to either the upper or lower compartment. At the end of a 10-day growth period, the specific activity of phosphate was determined in axillary shoots which developed during the course of the experiment from buds in the upper compartment. The results indicated that most of the phosphate in these shoots was not absorbed from the ambient medium but was derived from the rooted stem base in the lower compartment (over 90 % in Myriophyllum brasiliense, 59 % in M. spicatum, and 74 % in Elodea densa). These results give a very different but probably more accurate picture of phosphate absorption in rooted aquatic vascular plants than short-term experiments, in which phosphate is readily taken up from the ambient medium by leaves of M. spicatum and E. densa. In M. brasiliense the amount of phosphate translocated is related to the mass of roots present. Evidence is presented that normal growth of axillary shoots occurs even when all mineral ions have to be obtained by translocation from the lower compartment.     

Sexual behavior and male volatile compounds in wild and mass‐reared strains of the Mexican fruit fly Anastrepha ludens (Diptera: Tephritidae) held under different colony management regimes

We compared the calling and mating behavior and volatile release of wild males Anastrepha ludens (Loew) with males from 4 mass‐reared strains: (i) a standard mass‐reared colony (control), (ii) a genetic sexing strain (Tap‐7), (iii) a colony started from males selected on their survival and mating competitiveness abilities (selected), and (iv) a hybrid colony started by crossing wild males with control females. Selected and wild males were more competitive, achieving more matings under field cage conditions. Mass‐reared strains showed higher percentages of pheromone calling males under field conditions except for Tap‐7 males, which showed the highest percentages of pheromone calling males under laboratory cage conditions. For mature males of all strains, field‐cage calling behavior increased during the last hour before sunset, with almost a 2 fold increase exhibited by wild males during the last half hour. The highest peak mating activity of the 4 mass‐reared strains occurred 30 min earlier than for wild males. By means of solid phase microextraction (SPME) plus gas chromatography‐mass spectrometry (GC‐MS), the composition of volatiles released by males was analyzed and quantified. Wild males emitted significantly less amounts of (E,E)‐α‐farnesene but emitted significantly more amounts of (E,E)‐suspensolide as they aged than mass‐reared males. Within the 4 mass‐reared strains, Tap‐7 released significantly more amounts of (E,E)‐α‐farnesene and hybrid more of (E,E)‐suspensolide. Differences in chemical composition could be explained by the intrinsic characteristics of the strains and the colony management regimes. Characterization of calling behavior and age changes of volatile composition between wild and mass‐reared strains could explain the differences in mating competitiveness and may be useful for optimizing the sterile insect technique in A. ludens.     

Chemical Composition and Antimicrobial Activity of the Essential Oil from the Edible Aromatic Plant Aristolochia delavayi

The essential oil obtained by hydrodistillation from the aerial parts of Aristolochia delavayi Franch. (Aristolochiaceae), a unique edible aromatic plant consumed by the Nakhi (Naxi) people in Yunnan, China, was investigated using GC/MS analysis. In total, 95 components, representing more than 95% of the oil composition, were identified, and the main constituents found were (E)‐dec‐2‐enal (52.0%), (E)‐dodec‐2‐enal (6.8%), dodecanal (3.35%), heptanal (2.88%), and decanal (2.63%). The essential oil showed strong inhibitory activity (96% reduction) of the production of bacterial volatile sulfide compounds (VSC) by Klebsiella pneumoniae, an effect that was comparable with that of the reference compound citral (91% reduction). Moreover, the antimicrobial activity of the essential oil and the isolated major compound against eight bacterial and six fungal strains were evaluated. The essential oil showed significant antibacterial activity against Providencia stuartii and Escherichia coli, with minimal inhibitory concentrations (MIC) ranging from 3.9 to 62.5 μg/ml. The oil also showed strong inhibitory activity against the fungal strains Trichophyton ajelloi, Trichophyton terrestre, Candida glabrata, Candida guilliermondii, and Cryptococcus neoformans, with MIC values ranging from 3.9 to 31.25 μg/ml, while (E)‐dec‐2‐enal presented a lower antifungal activity than the essential oil.     

Chromium ions phytoaccumulation by three floating aquatic macrophytes from a nutrient medium

In the present work, the trivalent and hexavalent chromium phytoaccumulation by three living free floating aquatic macrophytes Salvinia auriculata, Pistia stratiotes, and Eicchornia crassipes was investigated in greenhouse. These plants were grown in hydroponic solutions supplied with non-toxic Cr³⁺ and Cr⁶⁺ chromium concentrations, performing six collections of nutrient media and plants in time from a batch system. The total chromium concentrations into Cr-doped hydroponic media and dry roots and aerial parts were assayed, by using the Synchrotron radiation X-ray fluorescence technique. The aquatic plant-based chromium removal data were described by using a nonstructural kinetic model, obtaining different bioaccumulation rate, ranging from 0.015 to 0.837 l mg⁻¹ d⁻¹. The Cr³⁺ removal efficiency was about 90%, 50%, and 90% for the E. crassipes, P. stratiotes, and S. auriculata, respectively; while it was rather different for Cr⁶⁺ one, with values about 50%, 70%, and 90% for the E. crassipes, P. stratiotes, and S. auriculata.     

Effective antimicrobial activity of Cbf‐K16 and Cbf‐A7A13 against NDM‐1‐carrying Escherichia coli by DNA binding after penetrating the cytoplasmic membrane in vitro

New Delhi metallo‐beta‐lactamase‐1(NDM‐1)‐carrying isolates, which are resistant to most clinical used antibiotics except for tigecycline and colistin, have been found worldwide. Cathelicidin‐BF (BF‐30) is found in the venom of the snake Bungarus fasciatus and exhibits broad antimicrobial activity. Cbf‐K₁₆ and Cbf‐A₇A₁₃ were obtained by mutating Lys¹⁶, Ala⁷, and Ala¹³ of BF‐30, respectively. To investigate their antimicrobial activities against NDM‐1 carrying bacteria, recombinant Escherichia coli BL21 (DE3)‐NDM‐1 with high NDM‐1 activity was constructed by inserting the Klebsiella pneumoniae NDM‐1 gene (GenBank accession no. HQ328085) into a pET28a vector and transforming it into E. coli BL21 (DE3). The peptides showed effective antimicrobial activities against NDM‐1‐carrying E. coli, and the minimum inhibitory concentrations of Cbf‐K₁₆ and Cbf‐A₇A₁₃ were only 4 and 8 µg/ml, whereas those of minimum bactericidal concentrations were 8 and 16 µg/ml, respectively. A time course experiment showed that colony forming unit counts rapidly decreased, and bacteria were thoroughly eliminated within 3 and 6 h by the Cbf‐K₁₆ and Cbf‐A₇A₁₃ treatments, respectively. The peptides penetrated the bacterial cell membrane and enabled β‐galactosidase leakage, and caused the cytoplasmic membrane to become permeable, and finally bound to the DNA. The genomic DNA of E. coli was completely unable to migrate on an agarose gel after Cbf‐K₁₆ treatment (8 µg/ml). These data demonstrated that Cbf‐K₁₆ and Cbf‐A₇A₁₃ possess effective antimicrobial activity against drug‐resistant strains, including NDM‐1 carrying E. coli BL21 (DE3)‐NDM‐1, by binding to DNA after penetrating the cytoplasmic membrane in vitro, which may have potential therapeutic value for the treatment of NDM‐1‐carrying bacterial infections. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Expression of lima bean terpene synthases in rice enhances recruitment of a beneficial enemy of a major rice pest

Volatile terpenoids play a key role in plant defence against herbivory by attracting parasitic wasps. We identified seven terpene synthase genes from lima bean, Phaseolus lunatus L. following treatment with either the elicitor alamethicin or spider mites, Tetranychus cinnabarinus. Four of the genes (Pltps2, Pltps3, Pltps4 and Pltps5) were up‐regulated with their derived proteins phylogenetically clustered in the TPS‐g subfamily and PlTPS3 positioned at the base of this cluster. Recombinant PlTPS3 was able to convert geranyl diphosphate and farnesyl diphosphate to linalool and (E)‐nerolidol, the latter being precursor of the homoterpene (E)‐4,8‐dimethyl‐1,3,7‐nonatriene (DMNT). Recombinant PlTPS4 showed a different substrate specificity and produced linalool and (E)‐nerolidol, as well as (E,E)‐geranyllinalool from geranylgeranyl diphosphate. Transgenic rice expressing Pltps3 emitted significantly more (S)‐linalool and DMNT than wild‐type plants, whereas transgenic rice expressing Pltps4 produced (S)‐linalool, DMNT and (E,E)‐4,8,12‐trimethyl‐1,3,7,11‐tridecatetraene (TMTT). In laboratory bioassays, female Cotesia chilonis, the natural enemy of the striped rice stemborer, Chilo suppressalis, were significantly attracted to the transgenic plants and their volatiles. We further confirmed this with synthetic blends mimicking natural rice volatile composition. Our study demonstrates that the transformation of rice to produce volatile terpenoids has the potential to enhance plant indirect defence through natural enemy recruitment.     

Regeneration and transformation of Eucalyptus camaldulensis

Reliable regeneration protocols for Eucalyptus camaldulensis using leaf explants from in vitro-grown plants have been developed. Out of the 24 clones tested 13 were regenerated and of these, 6 showed regeneration from more than 60% of the explants. Identical protocols were also successful in the regeneration of some clones of E. microtheca, E. ochrophloia, E. grandis and E. marginata, but at lower frequencies. Co-cultivation of E. camaldulensis leaf explants with Agrobacterium tumefaciens strains carrying a kanamycin resistance gene and the reporter gene β-glucuronidase (GUS), followed by selection on kanamycin at 9 mg l^–1, allowed the selection of transformed shoots that could be rooted on selective media. Transformation of the plants was verified by staining for the GUS enzyme in various plant tissues, NptII assays and by Southern blotting on isolated DNA using specific probes for both the GUS and selectable marker genes. Transformed tissue was obtained with 5 clones of E. camaldulensis tested and a number of A. tumefaciens strains. However, only 1 clone regenerated transformed whole plants reliably. Received: 14 October 1996 / Revision received: 18 February 1997 / Accepted: 1 April 1997     

Abundance estimation of riverine macrophyte Egeria densa using environmental DNA: effects of sampling season and location

Invasive macrophytes can have a variety of effects on aquatic ecosystems. The early detection and abundance estimation of an invasive species is important to effectively control it and minimize the ecosystem impacts. It is imperative to develop more efficient sampling methods for the abundance quantification of aquatic plants in large riverine systems. We examined (1) relationships between the environmental DNA (eDNA) concentrations of the invasive macrophyte, Egeria densa, and the upstream coverage area on the multiple life-history stages (dormant, growing, and senescence seasons) in a large riverine system in Japan and (2) if the relationships between the eDNA concentrations and coverage area could vary with the lateral sampling locations (left bank, middle, and right bank). The eDNA concentrations had significant positive relationships with the upstream coverage area of E. densa at multiple spatial scales for the dormant and senescence seasons. These results suggest that the eDNA analysis could be useful to quantify the relative abundance of this aquatic macrophyte in the riverine system; however, the selection of the eDNA sampling season could be important to accurately estimate abundance. Our results also showed that the eDNA concentrations of E. densa did not significantly differ from the lateral sampling location, suggesting that the eDNA samples could reflect the relative abundance of E. densa upstream of the study sites regardless of the lateral sampling location.

     

Toxicity of chlorpyrifos‐methyl to Sitophilus zeamais collected in Korea and biochemical differences

In this study, lethal concentration (LC₅₀) values of chlorpyrifos‐methyl (CPM) were determined for two Korean strains (CBNU and KNU) of Sitophilus zeamais. The two strains had similar susceptibilities (1.70 and 1.86 μg a.i./cm², respectively) to CPM. Carboxylesterase (CE) activity was twice as high in the CBNU strain as in the KNU strain. Lower acetylcholinesterase (AChE) activity was also noted in the latter; however, the activity of glutathione S‐transferase (GST) was twice as high as in the CBNU strain. Gel electrophoresis of CE of crude extracts from adults of the two strains of S. zeamais showed clearly different band patterns, with molecular weights of 60 kDa and 71 kDa in the CBNU and KNU strains, respectively. MALDI‐TOF MS/MS was used to profile small proteins (less than 10 kDa), with results indicating that 206 proteins are expressed differently in the two strains. The peak of interest of 2247.7 m/z was applied to TOF‐TOF MS and its de novo peptide sequence was identified as a tyrosine phosphatase fragment. Phospholipids from the two strains were analyzed and 34 phospholipids were found to be significantly different between strains. Results suggest that the two strains collected from Korea showed different biochemical results, presumably differences in insecticide selection by different living locations.     

Glutaminyl‐tRNA Synthetase from Pseudomonas aeruginosa: Characterization,structure, and development as a screening platform

Pseudomonas aeruginosa has a high potential for developing resistance to multiple antibiotics. The gene (glnS) encoding glutaminyl‐tRNA synthetase (GlnRS) from P. aeruginosa was cloned and the resulting protein characterized. GlnRS was kinetically evaluated and the K_M and k_cat^obs, governing interactions with tRNA, were 1.0 μM and 0.15 s^?1, respectively. The crystal structure of the α₂ form of P. aeruginosa GlnRS was solved to 1.9 Å resolution. The amino acid sequence and structure of P. aeruginosa GlnRS were analyzed and compared to that of GlnRS from Escherichia coli. Amino acids that interact with ATP, glutamine, and tRNA are well conserved and structure overlays indicate that both GlnRS proteins conform to a similar three‐dimensional structure. GlnRS was developed into a screening platform using scintillation proximity assay technology and used to screen ~2,000 chemical compounds. Three inhibitory compounds were identified and analyzed for enzymatic inhibition as well as minimum inhibitory concentrations against clinically relevant bacterial strains. Two of the compounds, BM02E04 and BM04H03, were selected for further studies. These compounds displayed broad‐spectrum antibacterial activity and exhibited moderate inhibitory activity against mutant efflux deficient strains of P. aeruginosa and E. coli. Growth of wild‐type strains was unaffected, indicating that efflux was likely responsible for the lack of sensitivity. The global mode of action was determined using time‐kill kinetics. BM04H03 did not inhibit the growth of human cell cultures at any concentration and BM02E04 only inhibit cultures at the highest concentration tested (400 μg/ml). In conclusion, GlnRS from P. aeruginosa is shown to have a structure similar to that of E. coli GlnRS and two natural product compounds were identified as inhibitors of P. aeruginosa GlnRS with the potential for utility as lead candidates in antibacterial drug development in a time of increased antibiotic resistance.     

Phosphate-solubilization mechanism and in vitro plant growth promotion activity mediated by Pantoea eucalypti isolated from Lotus tenuis rhizosphere in the Salado River Basin (Argentina)

Aims: To isolate and characterize phosphate‐solubilizing strains from a constrained environment such as the Salado River Basin and to assess their phosphate‐solubilizing mechanisms, to further selection of the most promising strains to inoculate and improve the implantation and persistence of Lotus tenuis in the most important area devoted to meat‐cow production in Argentina. Methods and Results: Fifty isolates were obtained and through BOX‐PCR analysis, 17 non‐redundant strains were identified. Subsequently, they were found to be related to Pantoea, Erwinia, Pseudomonas, Rhizobium and Enterobacter genera, via 16S rRNA gene sequence analysis. This was in agreement with the clusters obtained by antibiotic resistance analysis. All isolates were tested for their phosphate‐solubilizing activity and selected strains were inoculated onto L. tenuis plants. The most efficient isolate, was identified as Pantoea eucalypti, a novel species in terms of plant growth‐promoting rhizobacteria. Conclusions: The isolates obtained in this study showed a significant in vitro plant‐growth promoting activity onto Lotus tenuis and the best of them solubilizes phosphate mainly via induction of the metabolism through secretion and oxidation of gluconic acid. Singnificance and Impact of the Study: The use of these bacteria as bioinoculants, alone or in combination with nitrogen‐fixing micro‐organisms, could be a sustainable practice to facilitate the nutrient supply to Lotus tenuis plants and preventing negative side‐effects such as eutrophication.     

Synergistic activity of 1-(1-naphthylmethyl)-piperazine with ciprofloxacin against clinically resistant Staphylococcus aureus, as determined by different methods

Aims: To evaluate the interaction of 1‐(1‐naphthylmethyl)‐piperazine (NMP) and ciprofloxacin (CPFX) in vitro against fluoroquinolone (FQ)‐resistant clinical isolates of methicillin‐resistant Staphylococcus aureus (MRSA). Methods and Results: The in vitro interaction of NMP and CPFX in 12 FQ‐resistant clinical isolates of MRSA was assessed using a checkerboard microdilution method. In the study, a synergistic antimicrobial effect between NMP and CPFX was observed in all 12 FQ‐resistant strains tested, as determined by the fractional inhibitory concentration index (FICI), and in 10 strains using ΔE models. No antagonistic activity was observed in any of the strains tested. These positive interactions were also confirmed using the time–killing test and agar diffusion assay for the selected strain, MRSA 1862; synergistic activity was observed when NMP was combined with the first‐line antimicrobial agent CPFX against Staph. aureus. Conclusions: Synergistic activity between NMP and CPFX against clinical isolates of FQ‐resistant Staph. aureus was observed in vitro. Significance and Impact of the Study: This report might provide alternative methods to reduce the resistance of Staph. aureus to CPFX.     

Effects of mycorrhizal fungus isolates on mineral acquisition by Panicum virgatum in acidic soil

 Plant ability to withstand acidic soil mineral deficiencies and toxicities can be enhanced by root-arbuscular mycorrhizal fungus (AMF) symbioses. The AMF benefits to plants may be attributed to enhanced plant acquisition of mineral nutrients essential to plant growth and restricted acquisition of toxic elements. Switchgrass (Panicum virgatum L.) was grown in pH_Ca (soil:10 mM CaCl₂, 1 : 1) 4 and 5 soil (Typic Hapludult) inoculated with Glomus clarum, G. diaphanum, G. etunicatum, G. intraradices, Gigaspora albida, Gi. margarita, Gi. rosea, and Acaulospora morrowiae to determine differences among AMF isolates for mineral acquisition. Shoots of mycorrhizal (AM) plants had 6.2-fold P concentration differences when grown in pH_Ca 4 soil and 2.9-fold in pH_Ca 5 soil. Acquisition trends for the other mineral nutrients essential for plant growth were similar for AM plants grown in pH_Ca 4 and 5 soil, and differences among AMF isolates were generally higher for plants grown in pH_Ca 4 than in pH_Ca 5 soil. Both declines and increases in shoot concentrations of N, S, K, Ca, Mg, Zn, Cu, and Mn relative to nonmycorrhizal (nonAM) plants were noted for many AM plants. Differences among AM plants for N and Mg concentrations were relatively small (<2-fold) and were large (2- to 9-fold) for the other minerals. Shoot concentrations of mineral nutrients did not relate well to dry matter produced or to percentage root colonization. Except for Mn and one AMF isolate, shoot concentrations of Mn, Fe, B, and Al in AM plants were lower than in nonAM plants, and differences among AM plants for these minerals ranged from a low of 1.8-fold for Fe to as high as 6.9-fold for Mn. Some AMF isolates were effective in overcoming acidic soil mineral deficiency and toxicity problems that commonly occur with plants grown in acidic soil. Accepted: 14 June 1999     

Impact of encrusting carbonates on manganese,zinc and copper concentrations of two vascular hydrophytes from Texas

In alkaline calcareous waters, hydrophytes become encrusted with carbonate precipitates of a complex nature which alter bulk chemical analyses of the plants. The manganese, zinc and copper concentrations, and the ash content of two aquatic plants, Egeria densa and Potamogeton nodusus, differed considerably depending on the cleaning procedure used and, therefore, the amount of marl encrustation included in the analyses. Tapwater washed plants, retaining the marl, consistently had ash contents two to three times higher than acid-cleaned plants and exhibited higher trace metal concentrations, especially manganese.     

Influence of volatile compounds from herbivore‐damaged soybean plants on searching behavior of the egg parasitoid Telenomus podisi

Parasitoids use herbivore‐induced plant volatiles (HIPVs) to locate their hosts. However, there are few studies in soybean showing the mechanisms involved in the attraction of natural enemies to their hosts and prey. The objective of this study was to evaluate the influence of volatile organic compounds (VOCs) of soybean, Glycine max (L.) Merr. (Fabaceae) (cv. Dowling), that were induced after injury caused by Euschistus heros (Fabricius) (Hemiptera: Pentatomidae), on the searching behavior of the egg parasitoid Telenomus podisi Ashmead (Hymenoptera: Scelionidae). Four HIPVs from soybean, (E,E)‐α‐farnesene, methyl salicylate, (Z)‐3‐hexenyl acetate, and (E)‐2‐octen‐1‐ol, were selected, prepared from standards at various concentrations (10^?6 to 10^?1 m ), and tested individually and in combinations using a two‐choice olfactometer (type Y). Telenomus podisi displayed a preference only for (E,E)‐α‐farnesene at 10^?5 m when tested individually and compared to hexane, but they did not respond to the other compounds tested individually at any concentration or when combinations of these compounds were tested. However, the parasitoids stayed longer in the olfactometer arm with the mixture of (E,E)‐α‐farnesene + methyl salicylate at 10^?5 m than in the arm containing hexane. The results suggest that (E,E)‐α‐farnesene and methyl salicylate might help T. podisi to determine the presence of stink bugs on a plant. In addition, bioassays were conducted to compare (E,E)‐α‐farnesene vs. the volatiles emitted by undamaged and E. heros‐damaged plants, to evaluate whether (E,E)‐α‐farnesene was the main cue used by T. podisi or whether other minor compounds from the plants and/or the background might also be used to locate its host. The results suggest that minor volatile compounds from soybean plants or from its surroundings are involved in the host‐searching behavior of T. podisi.     

Detection of anti-tuberculosis activity in some folklore plants by radiometric BACTEC assay

Aims: The anti‐tubercular drugs are less effective because of the emergence of multi‐drug resistant (MDR) and extensively drug resistant (XDR) strains of M. tuberculosis, so plants being an alternative source of anti‐microbial compounds. The aim of this study was to investigate anti‐tuberculosis potential of the plants using Mycobacterium smegmatis as a rapid screening model for detection of anti‐mycobacterial activity and further to evaluate the active plants for anti‐tuberculosis activity against M. tuberculosis using radiometric BACTEC assay. Methods and Results: The 15 plants were screened for anti‐mycobacterial activity against M. smegmatis by the disk diffusion assay. The ethanolic extracts of Mallotus philippensis, Vitex negundo, Colebrookea oppositifolia, Rumex hastatus, Mimosa pudica, Kalanchoe integra and Flacourtia ramontchii were active against M. smegmatis in primary screening. The anti‐tuberculosis potential was identified in the leaves extracts of Mallotus philippensis by radiometric BACTEC assay. The ethanolic extract of M. philippensis showed anti‐tuberculosis activity against virulent and avirulent strains of M. tuberculosis H₃₇Rv and M. tuberculosis H₃₇Ra with minimum inhibitory concentration 0·25 and 0·125 mg ml^?1, respectively. The inhibition in growth index values of M. tuberculosis was observed in the presence of ethyl acetate fraction at a minimum concentration of 0·05 mg ml^?1. Conclusion: We found that BACTEC radiometric assay is a valuable method for detection of anti‐tuberculosis activity of the plant extracts. The results indicate that ethanolic extract and ethyl acetate fraction of M. philippensis exhibited significant anti‐mycobacterial activity against M. tuberculosis. Significance and Impact of the Study: These findings provide scientific evidence to support the traditional medicinal uses of M. philippensis and indicate a promising potential of this plant for the development of anti‐tuberculosis agent.     

Antifungal Effect and Protective Role of Ursolic Acid and Three Phenolic Derivatives in the Management of Sorghum Grain Mold Under Field Conditions

In this study, investigation was carried out under in vitro as well as field conditions to explore inhibitors of sorghum grain mold. Phytochemicals, viz., methyl trans‐p‐coumarate (AIC‐1), methyl caffeate (AIC‐2), syringic acid (AIC‐3), and ursolic acid (UA), at different concentrations (500, 750, and 1000 ppm) were tested on spore germination of Alternaria alternata, Curvularia lunata, Fusarium moniliforme, F. pallidoroseum, and Helminthosporium sp. Significant growth inhibition (P < 0.001) was observed against all fungi except A. alternata which was found to be resistant to AIC‐3. Further, two separate sets of field experiments involving spraying of water and F. moniliforme suspension over chemicals treated (1000 ppm) sorghum panicles were done. The levels of protection varied with different treatments which were graded using a standard 1 – 9 rating scale. The Fusarium‐challenged panicles (FCP) showed lesser susceptibility and decreased the rate of infection of grain mold (grade 7.0), compared to simple UA, AIC‐2, and AIC‐1 treatments (7.4, 7.6, and 8.0 grade, resp.). The HPLC quantification of differentially induced phenolic acids in treated sorghum grains substantiated this effect disclosing the higher accumulation of chlorogenic, vanillic, and salicylic acids in FCP. This might be due to defensive induction of these acids by the plants. Although mold control by examined chemicals were lesser than the standard Tilt (grade 5.9), they were found to be nontoxic to mammalian cells under cytotoxicity assay.     

Introduction of Nonindigenous Aquatic Vascular Plants in Southern New England: A Historical Perspective

Aquatic plants comprise few species worldwide, yet introductions of nonindigenous hydrophytes represent some of the most severe examples of biological invasions. Often innocuous in their indigenous regions, many aquatic plant species have caused extreme ecological and economic consequences when introduced into nonindigenous habitats. Typically, aquatic plant invasions are unnoticed or overlooked until they are perceived as problematic. By then, plants are virtually impossible to eradicate and negative ecological impacts caused by their spread into natural communities are irreparable. We present criteria to facilitate decisions whether a species should be characterized as nonindigenous or invasive. Historical data are used to clarify methods of introduction, avenues and means of dispersal, and extent of invasiveness of the following aquatic plants in southern New England: Acorus calamus, Butomus umbellatus, Cabomba caroliniana, Callitriche stagnalis, Egeria densa, Hydrilla verticillata, Limnobium spongia, Marsilea quadrifolia, Myriophyllum aquaticum, Myriophyllum heterophyllum, Myriophyllum spicatum, Najas minor, Najas guadalupensis, Nasturtium officinale, Nymphoides peltata, Potamogeton crispus, Trapa natans and Veronica beccabunga.