Resistance of wild rices, Oryza spp., to the brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

Of the 128 wild rices screened, 83 accessions were resistant to the brown planthopper Nilaparvata lugens (Stål). Resistant accessions were non-preferred and significantly more individuals settled on susceptible TN1 plants than on resistant ones. The quantity of food ingested and assimilated by N. lugens on resistant accessions was less than on susceptible TN1. N. lugens caged on resistant accessions had slow nymphal development, reduced longevity and low fecundity. Two wild rice species, Oryza officinalis and O. punctata, reduced the percentage hatchability of N. lugens eggs. A significant reduction in population growth was observed on resistant accessions compared with susceptible TN1.     

A quantitative method for detecting ammonia‐oxidizing bacteria in coastal aquaculture systems

There is a need to quantify autotrophic nitrifiers in coastal aquaculture systems for evolving a bioremediation strategy. Autotrophic nitrifiers are extremely slow‐growing organisms, which cannot be detected by traditional methods as they are notoriously difficult to culture. Molecular techniques based on functional genes could be deployed for the detection of nitrifiers. Ammonia monooxygenase (amoA), that catalyses the oxidation of ammonia to hydroxylamine in the rate‐determining step of nitrification is largely unique to ammonia‐oxidizing bacteria (AOB). In the present study, a quantitative real‐time polymerase chain reaction assay targeting amoA was developed to estimate AOB population size in coastal soil, ammonia‐removing bioaugmentors and the solid matrix. To achieve this objective, different set of primers and a dual labelled probe have been designed for SYBR Green and TaqMan real‐time assays. The abundance of AOB ranged from 10⁴ to 10⁶ order of magnitude in the samples. In the present study, biofilm formation of the consortium of nitrifying bacteria onto bagasse has also been quantified. The results demonstrate that the developed method is a rapid and sensitive tool for the quantitative detection of nitrifying bacteria in aquatic and related environment. This helps in making the bioremediation approach for ammonia removal by immobilization of nitrifying bacteria onto the natural substrate.     

Phenotypic and genotypic antimicrobial resistance patterns of Escherichia coli isolated from dairy cows with mastitis

Pulsed field gel electrophoresis (PFGE) patterns, susceptibility to 26 antimicrobial agents used in veterinary and human medicine, and prevalence of antimicrobial resistance genes of Escherichia coli isolated from cows with mastitis were evaluated. Among 135 E. coli isolates, PFGE analysis revealed 85 different genetic patterns. All E. coli were resistant to two or more antimicrobials in different combinations. Most E. coli were resistant to antimicrobials used in veterinary medicine including ampicillin (98.4%, >or=32 microg/ml) and many E. coli were resistant to streptomycin (40.3%, >or=64 microg/ml), sulfisoxazole (34.1%, >or=512 microg/ml), and tetracycline (24.8%, >or=16 microg/ml). Most E. coli were resistant to antimicrobials used in human medicine including aztreonam (97.7%, >or=32 microg/ml) and cefaclor (89.9%, >or=32 microg/ml). Some E. coli were resistant to nitrofurantoin (38%, >or=128 microg/ml), cefuroxime (22.5%, >or=32 microg/ml), fosfomycin (17.8%, >or=256 microg/ml). All E. coli were susceptible to ciprofloxacin and cinoxacin. Almost 97% (123 of 127) of ampicillin-resistant isolates carried ampC. Eleven of 52 (21.2%) streptomycin-resistant isolates carried strA, strB and aadA together and 29 streptomycin-resistant isolates (55.8%) carried aadA alone. Among 44 sulfisoxazole-resistant E. coli, 1 isolate (2.3%) carried both sulI and sulII, 12 (27.3%) carried sulI and 10 (22.7%) isolates carried sulII. Among 32 tetracycline-resistant isolates, 14 (43.8%) carried both tetA and tetC and 14 (43.8%) carried tetC. Results of this study demonstrated that E. coli from cows with mastitis were genotypically different, multidrug resistant and carried multiple resistance genes. These bacteria can be a reservoir for antimicrobial resistance genes and can play a role in the dissemination of antimicrobial resistance genes to other pathogenic and commensal bacteria in the dairy farm environment.     

Antifungal activity of some essential oils

Thirteen essential oils recovered by steam distillation from Indian herbs were analyzed for their chemical compositions using GC and GCMS. The antifungal activity against plant and Food mold rot were examined in vitro using poison food technique. The essential oil from cymbopogan exhibited control over all the plant and food mold rot tested. The bioactive compound in the oil and its minimum inhibitory concentration were determined using TLC bioautography.     

Genetic mapping of quantitative trait loci conditioning salt tolerance in wild soybean (Glycine soja) PI 483463

Salt tolerance in soybean [Glycine max (L.) Merr.] is controlled by major quantitative trait loci (QTL) or single gene(s). Among soybean germplasm, wild soybean plant introduction PI 483463 was reported to have a single dominant gene for salt tolerance. The objective of this study was to genetically map the QTL in a recombinant inbred line (RIL) population derived from a cross between PI 483463 and Hutcheson. Simple sequence repeat (SSR) markers and universal soybean single nucleotide polymorphism (SNP) panel (the USLP 1.0) were utilized for molecular genotyping. The RILs were phenotyped in two independent tests in a greenhouse using a 1–5 scale visual rating method. The results showed that the salt tolerant QTL in PI 483463 was mapped to chromosome 3 in a genomic region between the Satt255 and BARC-038333-10036 markers. The favorable allele inherited from PI 483463 conferred tolerance to salinity and had an additive effect on reducing leaf scorch. A subset of 66 iso-lines was developed from the F₃ families of the same cross and was used for genetic confirmation of the QTL. The integration of recombination events and the salt reaction data indicate that the QTL is located in the region of approximately a 658 kb segment between SSR03_1335 at nucleotide 40,505,992 and SSR03_1359 at nucleotide 41,164,735 on chromosome 3. This narrow region can facilitate further genomic research for salt tolerance in soybean including cloning salt tolerance genes.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.     

Role of earhead bug (leptocorisa acuta) feeding on sheath rot disease caused bysarocladium oryzae inoryza sativa in India

A study was conducted to determine the role of the earhead bug (Leptocorisa acuta Thumb. [Heteroptera: Alydidae]) in the manifestation of sheath rot disease caused bySarocladium oryzae (Sawada) W. Gams & D. Hawksw. [syn.Acrocylindrium oryzae (Sawada)], with the aim of formulating effective control measures against the disease. In greenhouse studies, rice plants (Oryza sativa, cv. IR 20) exhibited typical sheath rot within 12 days whenS. oryzae spore suspensions (5 x 10⁷ conidia/ml) were sprayed on earhead bug-infested plants (5 bugs/tiller). In a comparison of various inoculation methods, swabbing a spore suspension (using a camel?s hair brash) on the sheath surface of earhead bug-infested plants, and inserting a single-grain culture inside the sheath of infested plants, produced the greatest disease severity within 18 days of inoculation. The results demonstrated (a) the role of the earhead bug in sheath rot disease manifestation and (b) that rice genotypes can be screened effectively and rapidly in the greenhouse for resistance to the disease, using the described inoculation techniques.     

Cathepsin L cysteine proteinase in the diagnosis of bovine Fasciola gigantica infection

Cathepsin L cysteine proteinase from Fasciola gigantica was evaluated for its potential in the early prepatent detection of this helminth infection in bovine calves. Five cross-bred bovine calves were experimentally infected with 400 metacercariae/calf and evaluated for anti-cathepsin L antibody response. F. gigantica infection in these calves could be detected 4 weeks post-infection using an ELISA, dipstick ELISA and Western blotting with 100% sensitivity. The antigen was also used to detect F. gigantica field infection in cattle, by screening 256 sera of these animals by an ELISA, which demonstrated an overall infection rate of 26.95%. Preliminary studies showed that F. gigantica cathepsin L cysteine proteinase does not cross-react with Paramphistomum epiclitum, Gigantocotyle explanatum and hydatid cyst antigens. However, extensive studies on the cross-reactivity of this antigen with related helminth parasites of cattle and buffaloes are required, before this antigen can be considered suitable for immuno-diagnosis of fasciolosis in these ruminants.     

Evaluation of genetic diversity in Korean soybean landraces by protein banding patterns using high-throughput screening

The agronomic performance and storage protein patterns of 722 soybean landraces collected from eight geographically different Korean locations were investigated. The days to 50% flowering, days to maturity, and 100-seed weight ranged from 68.9 to 71.9 (d), 140.1 to 146.6 (d), and 22.4 to 26.8 (g), respectively. High-throughput protein profiling electrophoresis was performed, and the banding patterns were analyzed. Among the 722 soybean landraces, lipoxygenase bands were found to be absent in 21 lines. Nei’s gene diversity (h) ranged from 0 to 0.2642, with an average value of 0.1565. The mean coefficient of gene differentiation (Gst) was 0.0944, and the estimated gene flow (Nm) in the population was 4.7971. In a correlation matrix between the agronomic traits and protein banding patterns, the acidic banding pattern was significantly associated with all the other factors. The phenotypic and genotypic differences of the collection areas were evaluated, and the excellent soybean lines with high-value proteins, including 11S globulins, or without antinutritional factors such as lipoxygenase and trypsin inhibitor were selected.