French Bean Plants Research Articles

Investigating the uptake and fate of per- and polyfluoroalkylated substances (PFAS) in bean plants (Phaseolus vulgaris): comparison between target MS and sum parameter analysis via HR-CS-GFMAS

In this study, we present a screening method based on molecular absorption spectrometry to study PFAS uptake and fate in plants. To evaluate the suitability of this method we analyzed plant extracts with molecular absorption spectrometry (MAS) as well as liquid chromatography–tandem mass spectrometry (LC–MS/MS) for mass balance studies (w(F)). French bean plants (Phaseolus vulgaris) were grown on soil spiked using eight PFAS substances that vary in chain length and functional group composition. Specifically, these include three short-chained (C4–C5), five long-chained (C7–C10) carboxylic acids, one sulfonic acid and one sulfonic amide moieties. To investigate substance-specific PFAS uptake systematically, PFAS were spiked as single substance spike. Additionally, we studied one mixture of the investigated substances in equal proportions regarding w(F) and four PFAS mixtures of unknown composition. After 6 weeks, the plants were separated into four compartments. We analyzed the four compartments as well as the soil for extractable organically bound fluorine (EOF) by high resolution-continuum source-graphite furnace-molecular absorption spectrometry (HR-CS-GFMAS) as well as for sum of ten target-PFAS by LC–MS/MS. All three short-chained PFAS perfluorobutanoic acid (PFBA), perfluorobutanoic sulfonic acid (PFBS) and perfluoropentanoic acid (PFPeA) were determined in high concentrations mainly in the fruits of the investigated plants while long-chained PFAS perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) were mainly determined in roots. PFBS was determined in remarkably high concentrations in leaves compartment by both quantification methods. Overall, comprehensive results of single substance spikes were in good agreement for both methods except for a few cases. Hence, two phenomena were identified: for mixed PFAS spikes of unknown composition huge differences between EOF and sum of target PFAS were observed with systematically higher EOF values. Overall, both methods indicate comparable results with MS being more reliable for known PFAS contamination and MAS being more valuable to identify PFAS exposure of unknown composition.Graphical

Magnetic treatment of irrigation water and its effect on French bean (Phaseolus vulgaris)

Abstract Magnetic water treatment (magnetic treatment device (MTD)) has long been a contentious procedure for domestic water treatment. This study examines the pros and cons of using different water types with and without a magnetic field treatment for growing French bean crop irrigation. The MTD used in this experiment works by ionizing the dissolved solid using a cathode and anode, electrolysing water using a dynamic pulse current at 50 kHz, and energizing the cations using a 7,000 Gauss magnet. The MTD of normal, waste and saline water enhanced the yield by 12.7, 16.9, and 20.07% over their respective control plots. Contrarily, seed protein (22.52 g/100 g), vitamin A (687.09 IU), potassium (212.44 mg/100 g), vitamin K (14.32 mg/100 g), and calcium (39.93 mg/100 g) reached their peak values when French bean plants were irrigated by magnetically treated wastewater. Na concentration in pods was significantly reduced when 3,000 mg/L of magnetically treated saline water was used to irrigate French bean plants. The MTD of irrigation water has also improved N and K desorption from colloidal soil complexes, which significantly helped make these two elements easily available to the plants and promoting better plant growth and yield. Overall, using the MTD, the overall characteristics of French bean were improved.

Assessing the role of ACC deaminase-producing bacteria in alleviating salinity stress and enhancing zinc uptake in plants by altering the root architecture of French bean (Phaseolus vulgaris) plants.

The consortium inoculation with strains R1 and R4 modified the root system to boost seedling growth, increase the zinc content of French bean pods, and reduce salinity stress. The present study demonstrated the effect of two 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-producing plant growth-promoting rhizobacteria (Pantoea agglomerans R1 and Pseudomonas fragi R4) alone and consortia on the root system development, French bean growth, and zinc content as well as salinity stress tolerance. Both the strains were characterized for ACC utilization activity (426.23 and 380.54nmol α-ketobutyrate mg protein-1h-1), indole acetic acid (IAA) production, phosphate solubilization, ammonia, hydrogen cyanide (HCN), and siderophore production. The strains exhibited zinc solubilization in both plate and broth assays with zinc oxide and zinc carbonate as zinc sources as validated by atomic absorption spectroscopy (AAS). Single or combined inoculations with the selected strains significantly modulated the architectural and morphological traits of the root system of French bean plants. Furthermore, the application of R1and R4 consortia has enhanced zinc content in roots (60.83mgkg-1), shoots (15.41mgkg-1), and pods (30.04mgkg-1) of French bean plants grown in ZnCO3 amended soil. In another set of pot experiments, the consortium bacterization has significantly enhanced length as well as fresh and dry biomass of roots and shoots of the French bean plant under saline stress conditions. Additionally, inoculation with ACC-degrading rhizobacterial strains has increased chlorophyll and carotenoid contents, osmoprotectant content, and antioxidative enzyme (catalase and peroxidase) activity in comparison to their counterparts exposed to salt treatments only. Current findings suggested ACC deaminase-producing rhizobacterial strains hold the potential to improve root architecture which in turn promotes plant growth under salt-stressed conditions as well as enhances micronutrient concentration in host plants.

Biological characteristics and parasitization potential of Encarsia formosa Gahan (Hymenoptera: Aphelinidae) on the whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae), a pest of greenhouse crops in north-western Indian Himalayas

BackgroundThe greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae) constitutes key pests of greenhouses and field crops, which have developed pesticide resistance over the years. It has emerged as a difficult pest to manage owing to its indiscriminate exposure to higher dosages of insecticides. The use of natural enemies is environmentally safe alternative management tactic. Efficacy of Encarsia formosa Gahan (Hymenoptera: Aphelinidae) was determined by studying its biological characteristics on T. vaporariorum.ResultsParasitization by E. formosa was higher on fourth-instar nymphs of the greenhouse whitefly (GHWF) (37.2%), which was at par with that of third instar (36.4%), both differing significantly to the parasitization observed in second instar (19.6%). Total developmental duration of the parasitoid was longer on second instar (33.2 days) than that of fourth instar (29.9 days). Adult longevity was found significantly higher for the adults that emerged from fourth-instar nymphs of GHWF, which was at par to that of third instar and longevity of E. formosa adults was significantly higher in the absence of parasitoid host. The size of parasitoid that emerged from different instars of GHWF varied non-significantly. T. vaporariorum was reared on brinjal, cucumber, French bean, lettuce, tobacco, and tomato plants for mass production of E. formosa. Among them, French bean and tobacco were found to be the best host plants for mass production of E. formosa based on higher parasitization (37.2%). Total developmental period varied from 26.4 to 27.3 days on different host plants, the variations being non-significant. The maximum adult longevity was observed on cucumber (8.0 days) in the absence of host, and the adult size of parasitoid varied non-significantly. Results on host to parasitoid ratio of 5:1, 10:1, 20:1, 40:1 and 80:1 revealed that parasitization rate varied from 61.2 to 95.0% with maximum parasitization recorded in host–parasitoid proportion of 20:1 and minimum in 80:1. The total developmental duration varied non-significantly among all the proportions (15.1–15.4 days). Adult longevity was higher in the proportion of 40:1 (6.5 days), which was at par to the proportion of 5:1 (6.2 days), 20:1 (6.2 days), 80:1 (6.2 days) and 10:1 (6.1 days) in the absence of the host, respectively.ConclusionThis study suggests that augmentative biological control of T. vaporariorum under polyhouse conditions with E. formosa appears to be an effective strategy for the management of this economic pest.

Foliar Application of Salicylic Acid Enhances the Endogenous Antioxidant and Hormone Systems and Attenuates the Adverse Effects of Salt Stress on Growth and Yield of French Bean Plants

Salicylic acid (SA) is one of the strongest candidates to be used as a salinity moderator. A hydroponic experiment was conducted to evaluate the effect of foliar application of SA (0.00, 0.75 and 1.50 mM) on growth, productivity, and some physiological and biochemical parameters of French beans (Phaseolus vulgaris L.) continuously exposed to three NaCl levels (0, 50 and 100 mM). NaCl treatment significantly reduced vegetative growth parameters (between 16–50%), membrane stability (10–15%), relative water content (25–31%), chlorophyll content (21–42%), macro- and micronutrient levels (13–52% and 4–49%, respectively), growth promoters (auxins, gibberellins, and cytokinins; 11–28%), and yield of green pods (22–39%), while the phenolic compounds contents (35–55%), total antioxidant capacity (34–51%), proline (60–100%) and malondialdehyde (18–51%) contents, peroxidase activity (35–41%), Na+ (122–152%) and Cl− (170%) ions and abscisic acid (20–30%) contents were significantly increased compared to the non-salt-stressed controls. Foliar application of SA at 0.75 mM was able to overcome the adverse effects of NaCl stress to variable extent, which allowed for close to 90% of the yield of control plants to be reached. In conclusion, this study demonstrated that foliar spraying of SA helped to reduce the harmful effects of NaCl stress on French bean via regulation of some physiological and biochemical processes. This could be the basis of an effective and low-cost strategy to cope with salt stress.

Plant Growth Promoting Rhizospheric Bacillus spp. Isolated from Black Pepper (Piper nigrum L.)

Background: The rhizosphere contains many beneficial microorganisms which have a positive action on plant growth and development. In both natural and controlled ecosystems, beneficial plant-associated bacteria play a key role in supporting and increasing plant health and growth. Methods: In this study, plant growth promoting Bacillus isolates associated with the rhizosphere of black pepper (Piper nigrum) were selected and used for bioassay experiments for the host plant as well as for two test plants viz. French bean (Phaseolus vulgaris) and Pea plant (Pisum sativum). Result: This investigation revealed that the isolates chosen for the study exert a positive effect on the growth of inoculated black pepper plants and the test plants as compared to uninoculated control. Molecular identification of the selected isolates was done based on 16S rRNA gene analysis. All the four isolates exerted a considerable influence on the growth of black pepper cuttings and there is a significant increase in the shoot height and root length compared to untreated cuttings. Seed bacterization of the two test plants resulted in the increment of plant height and a heavier fresh weight and dry weight when compared to control plants. Based on these findings, it is evident that the isolates can be employed to enhance the growth not only of black pepper but of the test plants as well. Hence, according to this study, the selected isolates could be used as plant growth-promoting inoculants to attain the desired results of stem cuttings and seed bacterization.

Exogenous Application of Methyl Jasmonate and Salicylic Acid Mitigates Drought-Induced Oxidative Damages in French Bean (Phaseolus vulgaris L.).

Drought stress impairs the normal growth and development of plants through various mechanisms including the induction of cellular oxidative stresses. The aim of this study was to evaluate the effect of the exogenous application of methyl jasmonate (MeJA) and salicylic acid (SA) on the growth, physiology, and antioxidant defense system of drought-stressed French bean plants. Application of MeJA (20 μM) or SA (2 mM) alone caused modest reductions in the harmful effects of drought. However, combined application substantially enhanced drought tolerance by improving the physiological activities and antioxidant defense system. The drought-induced generation of O2●− and H2O2, the MDA content, and the LOX activity were significantly lower in leaves when seeds or leaves were pre-treated with a combination of MeJA (10 μM) and SA (1 mM) than with either hormone alone. The combined application of MeJA and SA to drought-stressed plants also significantly increased the activities of the major antioxidant enzymes superoxide dismutase, catalase, peroxidase, glutathione peroxidase, and glutathione-S-transferase as well as the enzymes of the ascorbate–glutathione cycle. Taken together, our results suggest that seed or foliar application of a combination of MeJA and SA restore growth and normal physiological processes by triggering the antioxidant defense system in drought-stressed plants.

Critical Limits of Sulfur in Relation to the Growth and Development of French-bean and Cauliflower in Acidic Soils of Northwestern Himalayas

ABSTRACT Sulfur deficiency is recognized as a constraint to crop production all over the world from last decade. The soils of Northwestern Himalayas are also administering sulfur deficiency. To achieve higher yields with better nutritive quality, the plant fertilization management must include sulfur. Critical-level approach hardly advocated in vegetables, and no reports of critical limits of S were reported in Northwestern Himalayas. The present experiment on French bean and cauliflower on 10 types of soil (varying in pH and clay content) was laid out in completely randomized design under glass house with five levels of sulfur (0, 10, 20, 30, and 40 kg ha−1). Application of sulfur significantly increased the yield of French-bean and cauliflower as compared to no application of sulfur. The highest yield was obtained with application of 40 kg S ha−1 in both the crops. The green pod yield of French-bean at 30 kg S ha−1 was statistically at par with 40 kg S ha−1. Critical limits of sulfur in soil were 9.5 mg kg−1 and 10.5 mg kg−1 for French-bean and cauliflower, respectively. Critical limits of S in French-bean and cauliflower plants were 0.103 and 0.336% sulfur, respectively. Critical limits of S in French-bean and cauliflower will help to supply nutrients in balanced amount and to achieve sustainability in production.

Characterization of novel French bean leaf curl virus and betasatellite associated with leaf curl disease of French bean (Phaseolus vulgaris L.)

Leaves from French bean plants with severe leaf curl (ten samples) and from asymptomatic plants from 10 fields (FB1–10) in the Western Ghat region of Karnataka, India were collected. Virus isolate FB01 from French bean was shown to be transmitted by whitefly Bemisia tabaci cryptic species Asia I. DNA was isolated from the samples (ten field samples and one sample infected with FB01 via whitefly) and subjected to PCR to confirm begomovirus infection using specific primers. All 11 were positive for the expected 1.2-kb amplicon. The sequence analysis of the 1.2-kb amplicon showed that all isolates shared more than 98% nucleotide identity. Further, the complete genome from isolate FB01 was amplified and sequenced and shown to share a maximum nucleotide identity (89.3%) with Ageratum yellow vein Sri Lanka virus. As per the ICTV species threshold for begomoviruses, the virus is considered as a new species, with the proposed name French bean leaf curl virus (FbLCV). The samples were subjected to PCR using specific primers for DNA B, betasatellite and alphasatellite; only betasatellites were amplified. The detected betasatellite shared maximum nucleotide identity (92.6%) with Synedrella yellow vein betasatellite. Recombination analysis indicated that FbLCV and betasatellite were recombinants. The significance of these findings are discussed.

Diversity analysis of ACC deaminase producing bacteria associated with rhizosphere of coconut tree (Cocos nucifera L.) grown in Lakshadweep islands of India and their ability to promote plant growth under saline conditions

ACC deaminase producing Plant growth promoting rhizobacteria (PGPR) offers a great promise for ameliorating the negative impacts of salinity stress manifested on plants. In this context, 28 rhizospheric bacteria associated with ACC deaminase potential (198−1069 nmol α-ketobutyrate mg protein−1 h−1) were isolated from 5 different islands of Lakshadweep, union territory, India- Agatti, Kavaratti, Bangaram, Kadmat, and Thinnakara islands using DF-minimal medium. The diversity of cultivable ACC deaminase producing bacteria was analysed by PCR-RFLP (Restriction Fragment Length Polymorphism) method using three endonucleases AluI, MspI and HaeIII which led to the grouping of these isolates into six clusters at 80 % similarity index. Subsequently, isolates were functionally characterized for various PGP traits such that indole-3-acetic acid (IAA) production (∼10−80 μg mL−1); 16 isolates had phosphate solubilizing potential ranging from ∼19 to 88 P mg L−1 ; siderophore and ammonia production abilities were observed in 5 and 24 isolates, respectively while two strains tolerated up to 8% NaCl. Phylogenetic analysis of 16S rRNA gene sequences of representative strain from each cluster revealed that twenty-eight ACC deaminase producing PGPR belong to eight distinct genera: Pseudomonas, Bacillus, Azospirillum, Azotobacter, Escherichia, Paenibacillus, Burkholderia, and Klebsiella. Two isolates, CO1 (Pseudomonas putida) and CO8 (Bacillus paramycoides) were evaluated for plant growth promoting effects on French bean (Phaseolus vulgaris) under salinity (100 mM NaCl) stress. Both the selected isolates in consortium form significantly increased the root length, shoot length, root fresh and dry weight, shoot fresh and dry weight of French bean seedlings exposed to salinity stress, compared to non-inoculated control plants. The co-inoculation with selected strains CO1 and CO8 has significantly improved chlorophyll concentration, relative water content, membrane stability index, gas exchange parameters including net photosynthesis rate (PN), stomatal conductance (gs), transpiration rate (E) and water use efficiency of French bean plants by ∼100 %, ∼85 %, ∼40 %, ∼198 %, ∼80 %, ∼70 % and ∼75 %, respectively under saline conditions in comparison with non-inoculated plants. Moreover, the consortium treated French bean plants showed lower levels of stress-induced ethylene by 38 %, electrolyte leakage and Malondialdehyde (MDA) content by ∼15 % under salt stress compared to non-inoculated ones. This study unveiled the potential of halotolerant strains, Pseudomonas putida and Bacillus paramycoides as French bean biofertilizers in mitigating the adverse effects of salinity in plant growth in sustainable agriculture.

Effect of temperature on systemic infection and symptom expression induced by Soybean yellow mottle mosaic virus in leguminous hosts

Temperature is one of the key factors influencing the viral disease development in plants. In this study effect of temperature on SYMMV accumulation and systemic movement was studied in French bean, mungbean and soybean cultivars by keeping them at temperatures range 22-25 °C, 26-29 °C and 30-33 °C. The proliferation of the virus under these conditions was confirmed through symptomatology, DAC-ELISA, RT-PCR with coat protein specific primers and RT-qPCR. French bean plants displayed symptoms by 12dpi at low temperature (22-25 °C) and by 3dpi at medium temperatures (26-29 °C) with continuous increase in viral accumulation from 0 to 24dpi. At high temperatures (30-33 °C), French bean did not show symptoms up to 12dpi but the virus accumulated and moved systemically. However, there was a decline in viral copy number after 12dpi. Mungbean plants showed mottling, mosaic and puckering symptoms at 22-25 °C and 26-29 °C and necrotic symptoms at 30-33 °C. Irrespective of temperature there was an increase in viral accumulation in mungbean from 0 days to 24dpi. Soybean plants showed veinal mild mottling at low and medium temperatures where as no peculiar symptom expression observed at high temperatures. Soybean also showed the reduction of viral copy number from 12 days to 24dpi at low and medium temperatures and from 6 days to 24dpi at high temperatures. These results indicate that temperature played an important role in SYMMV accumulation, movement and symptom expression in these three leguminous plant species. This study also demonstrates that SYMMV can replicate and spread in mungbean plants irrespective of the temperature.

Seed transmission of a distinct soybean yellow mottle mosaic virus strain identified from India in natural and experimental hosts

Soybean yellow mottle mosaic virus (SYMMV) is a newly identified member of the genus Gammacarmovirus from grain legumes in India. As the modes of transmission of this virus have not been described, we assessed the possibility of SYMMV to be transmitted through seed collected from field infected mungbean plants and mechanically sap inoculated French bean plants using serological and molecular techniques followed by progeny assays. Direct antigen coated enzyme linked immunosorbent assay (DAC-ELISA) and reverse transcription polymerase chain reaction (RT-PCR) results are inconsistent with field infected mungbean seed tissues to ensure seed transmissibility irrespective of seed number used. Seed from mechanical sap inoculated French bean showed higher absorbance values in DAC-ELISA and amplification corresponding to replicase, movement and coat protein regions of SYMMV genome. The relative accumulation of SYMMV was higher in pod walls, immature seed and stamens and stigma of mechanical sap inoculated French bean. Progeny assays with infected seed revealed the seed transmissibility of SYMMV at the rate of 63.33% in mungbeanand 73.33% in French bean. Mechanical sap inoculation of mungbean progeny seedlings on French bean cv. Pusa Parvati produced characteristic symptoms of SYMMV. The results obtained from this study demonstrate that SYMMV is seed borne in nature and can be transmitted to next generation seedlings. This is the first report of seed transmission of SYMMV in mungbean and French bean.

Nematicidal Properties of Three Adjuvants for Management of Southern Root-Knot nematode, Meloidogyne incognita in vitro and under Greenhouse Conditions

Lettuce and French bean production are severely infected by root-knot nematode, Meloidogyne incognita which causes critical damage to economic plants. Therefore, the farmers have to use chemical nematicides with or without adding adjuvants to enhance the active ingredient delivery to the target nematode. A current study was conducted to assess the direct effect of three adjuvants namely Silwet L-77, Sylgard 309 and Agrimax 3H comparing with three formulations of oxamyl, fosthiazate and fenamiphos on root-knot nematode Meloidogyne incognita. In vitro experiments, ovicidal effect of Silwet L-77, Sylgard 309 and Agrimax 3H on eggs hatching of root-knot nematode was close to the lowest efficient nematicide fenamiphos when the adjuvants were applied at double recommended rate but their effect does not rise to the level of oxamyl or fosthiazate. On the other hand, mortality percentages of second-stage juveniles resulted from Silwet L-77, Sylgard 309 and Agrimax 3H at the recommended rate were 37.33, 50.00 and 42.19 %, respectively. Whereas, double recommended rate of such materials induced mortality percentages reached 46.66, 47.83 and 48.66 %, respectively comparing with 90.83,74.33 and 45.83% resulted from the tested nematicides oxamyl, fosthiazate and fenamiphos, respectively. On the other hand, controlling the root-knot nematode infecting lettuce and French bean plants under greenhouse conditions revealed that adjuvants have weak or limited nematicidal effect with minor potency in reduction nematode development incomparable with the tested standard nematicides, and does not rise to the lowest effect of a tested nematicide fenamiphos. However, both tested plants showed no visual phytotoxicity symptoms.

Impact of engineered nanomaterials either alone or loaded with NPK on growth and productivity of French bean plants: Seed priming vs foliar application

Nanotechnology has become a solution to most of the problems facing humans nowadays. In agriculture, nanofertilizers play a pioneer role to enrich crop productivity and minimize environmental pollution problems. In this paper we investigate the possible effects of using two engineered nanomaterials nanochitosan (Cs) or carbon nanotubes (CNTs) either alone or loaded with NPK as fertilizers on French bean plants. The new approach used was to compare between two different methods of application: seed priming and foliar application. From the obtained results, it is apparent that foliar application is better than seed priming. This is evident from the improvement of growth, yield, and antioxidant system of plants and biochemical content of yielded seeds of foliar application than in seed priming as compared with control. In addition, foliar treatment shortened the days to harvest without reducing yield by 37.5% (80 days) as compared with control and seed priming treatment (110 days). Of interest, Cs nanoparticles appeared to improve growth and yield parameters more than CNTs in foliar application treatment. In conclusion, foliar application of nanofertilizers holds tremendous potential to improve crop productivity and we recommend the use of nanofertilizers as foliar application.

First report of Tomato leaf curl Joydebpur virus infecting French bean (Phaseolus vulgaris L.)

During 2016-2017 in Bhagalpur, Bihar, northern India, French bean plants developed curling and yellow mosaic of leaves and stunting. In eight of 12 symptomatic plants, PCR tests for Mungbean yellow mosaic India virus were positive. In the four PCR-negative symptomatic plants, rolling circle amplification (RCA) detected a ~ 2.7-kb DNA that was identified as genomic DNA of Tomato leaf curl Joydebpur virus. Also a ~ 1.4-kb specific PCR product was identified as Tomato leaf curl Joydebpur betasatellite. Whitefly-mediated transmission to chili was as efficient as that to French bean. Our findings provide evidence of a monopartite begomovirus in French bean.

Development of Soybean Yellow Mottle Mosaic Virus-Based Expression Vector for Heterologous Protein Expression in French Bean.

Plant virus-based vectors provide attractive and valuable tools for rapid production of recombinant protein in large quantities as they produce systemic infections in differentiated plant tissues. In the present study, we engineered the Soybean yellow mottle mosaic virus (SYMMV) as a gene expression vector which is a promising candidate for systemic expression of foreign proteins in French bean plants. Full virus vector strategy was exploited for insertion of foreign gene by inserting MCS through PCR in the circular pJET-SYMMV clone. To examine the ability of the SYMMV vector system, GFP gene was cloned after the start codon of coat protein (CP) so that its expression was driven by the SYMMV-CP subgenomic promoter. When in vitro run off SYMMV-GFP transcript was mechanically inoculated to French bean leaves, good level of GFP expression was observed through confocal microscopy up to 40 dpi. Expression of heterologous protein was also confirmed through ISEM, DAC-ELISA and RT-PCR with specific primers at 20dpi. The recombinant SYMMV construct was stable in in vitro runoff transcript inoculated plants but the inserted GFP was lost in progeny virion inoculated plants. The system developed here will be useful for further studies of SYMMV gene functions and exploitation of SYMMV as a gene expression vector.

Short range dispersal of western flower thrips in field-grown French beans in Kenya

AbstractThe short-range diurnal dispersal pattern of adult western flower thripsFrankliniella occidentalis(Pergande), in relation to spatial distribution of French beans, was determined in the field. A total of 1200 adult femaleF. occidentaliswere released on 60 French bean plants with 20 adult thrips per plant at the central release point of 3.14 m2. Dispersal was determined in terms of the number of thrips recorded on French beans planted on concentric circles at 0.9, 1.8, 3.6, 7.2 and 14.4 m radii from a circular central release point for five days. Results indicated that there was a steady increase in the proportion of dispersing adultF. occidentalisfrom the first to the fourth day in the first planting season, and from the first to the third day in the second planting season. The peak hour for dispersal was 10.15 h in the first season while it was 13.15 h in the second season. Temperature and wind speed were positively associated with the dispersal activity of adultF. occidentalis. Minimal flight activity was at temperatures below 15 °C and peak flight activity was at 19 °C. The prevailing wind direction did not influence the dispersal pattern of adultF. occidentalisin both seasons. AdultF. occidentalismoved up to 7.2 m on French beans on the first day. In both seasons, the mean direction of thrips dispersal was mostly uniformly distributed (not oriented to a particular compass direction) around the central release point. The results provide an insight into developing integrated management strategies against the pest based on isolation of farm fields, management of alterative hosts around French bean fields and insecticide application.

Genome characterization, infectivity assays of in vitro and in vivo infectious transcripts of soybean yellow mottle mosaic virus from India reveals a novel short mild genotype

Nucleotide sequence of a distinct soybean yellow mottle mosaic virusisolate from Vignaradiata (mungbean isolate, SYMMV-Mb) from India was determined and compared with othermembers of the family Tombusviridae. The complete monopartite single-stranded RNA genome of SYMMV-Mb consisted of 3974nt with six putative open reading frames and includes 5′ and 3′ untranslated regions of 35 and 254nt, respectively. SYMMV-Mb genome shared 75% nt sequence identity at complete genome level and 67–92% identity at all ORFs level with SYMMV Korean and USA isolates (soybean isolates) followed by CPMoV, whereas it shared very low identity with other tombusviridae members (5–41%). A full-length infectious cDNA clone of the SYMMV-Mb placed under the control of the T7 RNA polymerase and the CaMV35S promoters was generated and French bean plants on mechanical inoculation with in vitro RNA transcripts, p35SSYMMV-O4 plasmid and agroinoculation with p35SSYMMV-O4 showed symptoms typical of SYMMV-Mb infection. The infection was confirmed by DAC-ELISA, ISEM, RT-PCR and mechanical transmission to new plant species. Further testing of different plant species with agroinoculation of p35SSYMMV-O4 showed delay in symptoms but indistinguishable from mechanical sap inoculation and the infection was confirmed by DAC-ELISA, RT-PCR and mechanical transmission to new plants. The system developed here will be useful for further studies on pathogenecity, viral gene functions, plant-virus-vector interactions of SYMMV-Mb and to utilize it as a gene expression and silencing vector.

Improving French Bean (PhaseolusVulgaris L.) Pod Yield and Quality Through the Use of Different Coloured Agronet Covers

French bean (Phaseolus vulgaris L.) is among important vegetables in supplying proteins, vitamins, minerals and dietary fiber to humans worldwide. Its successful production in the tropics is, however, constrained by abiotic and biotic stresses as the crop is predominantly grown in open fields. Netting technology has been proved successful in protecting crops against adverse weather and insect pests. Coloured net technology is an emerging technology, which introduces additional benefits on top of the various protective functions of nettings. Two trials were conducted at the Horticulture Research and Teaching Field, Egerton University, Kenya to evaluate the effects of different coloured agronet covers on growth, pod yield and quality of French bean. A randomized complete block design (RCBD) with six treatments and four replications was used. French bean plants were grown under a white, blue, yellow, tricolour or grey net cover with open field production as the control. Variables measured included days to emergence and emergence percentage (%), stem collar diameter, plant height, number of branches and internodes, internode length and crop yield. French bean grown under the different coloured net covers showed relatively better growth and crop performance marked by more pods and higher total yields and percentage of marketable yields compared to those grown in the open field. Growing French bean under net covers hastened the rate of pod maturation more-so under the light-coloured colour-nets. Findings of this study demonstrate the potential of coloured net covers in improving French bean pod yield and quality under tropical field conditions.

Effect of Using Two Different Types of Engineered Nanomaterials on The Growth and Antioxidant Enzymes of French Bean Plants

The application of nanomaterials in agriculture is one of the most greatly studied areas in nanotechnology as it includes the using of nanofertilizers to transport nutrient elements to the plant at the needed time and required amount, thereby improving the use efficiency. This work was designed to investigate the effects of soil incorporation of two different types of engineered nanofertilizer namely: carbon nanotubes and chitosan nanoparticles alone or loaded with nitrogen, phosphorus and potassium (NPK) on the different growth criteria of French bean plants. The results indicate that after about 30 days from the date of planting, nanomaterials either alone or in combination with NPK significantly decrease plant growth and increase the activity of antioxidant enzymes implying that French bean plants were exposed to an oxidative stress.