Purification, serology and physico-chemical properties of a peanut mottle virus isolate from India

A procedure developed for the purification of peanut mottle virus (PMV) isolated from peanuts in India yielded 30–40 mg of virus/kg of plant tissue. Purified virus sedimented as a single component of 151 S. The virus coat protein migrated as a single component in each of two polyacrylamide gel concentrations and had an estimated molecular weight of 34 000 daltons. The molecular weight of the nucleic acid was 3.10 × 106 daltons. In the precipitin ring interface test (PRIT) PMV showed a serological relationship with soybean mosaic virus (SMV). Using the double antibody sandwich form of ELISA, PMV was shown to be distantly related to adzuki bean mosaic (ABMV), amaranthus leaf mottle (ALMV), clover yellow vein (CYVV) viruses and SMV. Immunosorbent electron microscopy (ISEM) showed PMV to be closely related to ABMV, ALMV, CYVV and SMV. In PRIT, ELISA and ISEM tests no specific serological reaction was noted between PMV and antisera to groundnut eye spot, peanut green mosaic, pepper veinal mottle, potato virus Y, sugarcane mosaic and turnip mosaic viruses

Improved Serological Techniques for the Detection and Identification of Groundnut Viruses

Serology is indispensable for the detection and identification of plant viruses. Recently, the highly sensitive enzyme-linked immunosorbent assay (ELISA) and immunosorbent electron microscopy (ISEM) techniques have been developed and may replace some of the conventional serological methods. The direct or standard double-antibody sandwich (DAS) form of ELISA. as first described by Clark and Adams (1977), has wide applications in plant virology. An indirect form of ELISA (I-ELISA) has recently been developed by Barbara and Clark (1982). The ISEM procedure developed by Derrick (1973) combines the specificity of serology with coventional electron microscopy. DAS-ELISA, I-ELISA and ISEM have been adapted for the detection and identification of several groundnut viruses. This paper will provide a description of each technique and its application for the detection and characterization of viruses occurring on groundnut in India

Isolation and characterization of a geminivirus causing yellow mosaic disease of horsegram (Macrotyloma uniflorum (Lam.) Verdc.) in India.

Horsegram yellow mosaic disease was shown to be caused by a geminivirus; horsegram yellow mosaic virus (HYMV). The virus could not be transmitted by mechanical sap inoculation. Leaf dip and purified virus preparations showed geminate virus particles, measuring 15-18 * 30 nm. An antiserum for HYMV was produced and in enzyme-linked immunosorbent assay (ELISA) and immunosorbent electron microscopy (ISEM) tests HYMV was detected in leaf extracts of fieldinfected bambara groundnut, french bean, groundnut, limabean, mungbean, pigeonpea and soybean showing yellow mosaic symptoms. Bemisia tabaci fed on purified HYMV through a parafilm membrane transmitted the virus to all the hosts listed above but not to Ageratum conyzoides, okra, cassava, cowpea, Croton bonplandianus, Lab-lab purpureus, Malvastrum coromandalianum and tomato. No reaction was obtained in ELISA and ISEM tests between HYMV antibodies and extracts of plants diseased by whitefly-transmitted agents in India such as A. conyzoides yellow mosaic, okra yellow vein mosaic, C. bonplandianus, yellow vein mosaic, M. coromandalianum yellow vein mosaic, tomato leaf curl and cassava mosaic. HYMV was also not found to be related serologically to bean golden mosaic, virus

Indian Peanut Clump Virus Isolates: Host Range, Symptomatology, Serological Relationships, and Some Physical Properties

The symptomatology of Indian peanut clump virus (IPCV) isolates collected from five different geographical locations, Bapatla (B), Chinnaganjam (C), Hyderabad (H), Ludhiana (L), and Talod (T), differed. B-IPCV and C-IPCV were indistinguishable by host range but could be distinguished from the other isolates by symptoms on Canavalia ensiformis, Nicotiana clevelandii × glutinosa, Phaseolus vulgaris, and Vigna unguiculata. B-IPCV, C-IPCV, and T-IPCV were related serologically, but could be distinguished from H-IPCV and L-IPCV isolates in serological tests. The five isolates could not be distinguished on the basis of particle size. Each isolate contained two RNA species of 1.90 × 106 and 1.65 × 106 Mr estimated under nondenaturing conditions and a single polypeptide of 24 × 103 Mr. Significance of these findings for the diagnosis of IPCV and for screening of peanut genotypes for resistance is discussed

The occurrence of Indian peanut clump, a soil-borne virus disease of groundnuts (Arachis hypogaea) in India

A disease characterised by severely stunted plants with small dark green leaves was found in groundnut (Arachis hypogaea) in sandy soils in Punjab State, India. The disease occurred in patches in the field and reappeared in the same positions in succeeding groundnut crops. Plants infected early did not produce mature pods. Seeds sown in soil collected from infected fields produced plants with typical disease symptoms. Phaseolus vulgaris cv. Local and Chenopodium quinoa were found to be good diagnostic hosts. The disease was shown to be caused by a rod-shaped virus c. 24 nm in diameter with predominant particle lengths of c. 249 and 184 nm when stained in uranyl acetate. The virus, named Indian peanut clump virus (IPCV), resembled peanut clump virus (PCV) reported from W. Africa in symptomatology on groundnuts, particle morphology and soil-borne nature. However, it is not serologically related to two W. African PCV isolates tested, or to tobacco rattle (PRN and CAM strains) or pea early browning virus (Dutch isolate) in microprecipitin, enzyme linked immunosorbent assay and immunosorbent electron microscopy tests

Studies on transmission of Indian peanut clump virus disease by Polymyxa graminis

The plasmodiophoromycete fungus, Polymyxa graminis was observed in the roots of Sorghum bicolor, S. sudanense, Pennisetum glaucum, Triticum aestivum, Cyperus rotundus, Eleucine coracana, Zea mays, Tridax procumbens and Arachis hypogaea collected from Indian peanut clump virus (IPCV)-infested fields. Examination of roots of IPCV-infected S. bicolor, S. sudanense, P. glaucum and T. aestivum grown in previously air dried field soil also showed the presence of cystosori of P. graminis. IPCV-infested soil stored at room temperature for 3 years transmitted the virus to A. hypogaea, T. aestivum and S. bicolor. Roots extracted from IPCV-infected P. glaucum and S. bicolor containing cystosori, and dried root fragments incorporated into sterile soil, transmitted the virus to A. hypogaea and T. aestivum. The root extracts contained primary zoospores of the fungus, presumably arising from cystosori. Utilising root fragments of S. sudanense containing cystosori as inoculum P. graminis was shown to infect both monocotyledonous and dicotyledonous plants. Profuse cystosorus production in rootlets only occurred in monocotyledonous plants. In dicotyledonous plants, in general, only few rootlets showed cystosori. Indian isolates of P. graminis appear to differ from isolates from temperate soils in that they can infect dicotyledonous plants and have a much wider host rang

Strong absorption by interstellar hydrogen fluoride: Herschel/HIFI observations of the sight-line to G10.6-0.4 (W31C)

We report the detection of strong absorption by interstellar hydrogen fluoride along the sight-line to the submillimeter continuum source G10.6-0.4 (W31C). We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 1232.4763 GHz J=1-0 HF transition in the upper sideband of the Band 5a receiver. The resultant spectrum shows weak HF emission from G10.6-0.4 at LSR velocities in the range -10 to -3 km/s, accompanied by strong absorption by foreground material at LSR velocities in the range 15 to 50 km/s. The spectrum is similar to that of the 1113.3430 GHz 1(11)-0(00) transition of para-water, although at some frequencies the HF (hydrogen fluoride) optical depth clearly exceeds that of para-H2O. The optically-thick HF absorption that we have observed places a conservative lower limit of 1.6E+14 cm-2 on the HF column density along the sight-line to G10.6-0.4. Our lower limit on the HF abundance, 6E-9 relative to hydrogen nuclei, implies that hydrogen fluoride accounts for between ~ 30 and 100% of the fluorine nuclei in the gas phase along this sight-line. This observation corroborates theoretical predictions that - because the unique thermochemistry of fluorine permits the exothermic reaction of F atoms with molecular hydrogen - HF will be the dominant reservoir of interstellar fluorine under a wide range of conditions.Comment: Accepted for publication in Astronomy and Astrophysics (Herschel special issue). This revised version corrects a typographic error in the HTML abstract, in which the lower limit on the HF abundance (should be 6E-9) was previously misstated. The abstract in the PDF version is correct and the latter has not been modifie

Detection of hydrogen fluoride absorption in diffuse molecular clouds with Herschel/HIFI: a ubiquitous tracer of molecular gas

We discuss the detection of absorption by interstellar hydrogen fluoride (HF) along the sight line to the submillimeter continuum sources W49N and W51. We have used Herschel's HIFI instrument in dual beam switch mode to observe the 1232.4762 GHz J = 1 - 0 HF transition in the upper sideband of the band 5a receiver. We detected foreground absorption by HF toward both sources over a wide range of velocities. Optically thin absorption components were detected on both sight lines, allowing us to measure - as opposed to obtain a lower limit on - the column density of HF for the first time. As in previous observations of HF toward the source G10.6-0.4, the derived HF column density is typically comparable to that of water vapor, even though the elemental abundance of oxygen is greater than that of fluorine by four orders of magnitude. We used the rather uncertain N(CH)-N(H2) relationship derived previously toward diffuse molecular clouds to infer the molecular hydrogen column density in the clouds exhibiting HF absorption. Within the uncertainties, we find that the abundance of HF with respect to H2 is consistent with the theoretical prediction that HF is the main reservoir of gas-phase fluorine for these clouds. Thus, hydrogen fluoride has the potential to become an excellent tracer of molecular hydrogen, and provides a sensitive probe of clouds of small H2 column density. Indeed, the observations of hydrogen fluoride reported here reveal the presence of a low column density diffuse molecular cloud along the W51 sight line, at an LSR velocity of ~ 24kms-1, that had not been identified in molecular absorption line studies prior to the launch of Herschel.Comment: 4 pages, 3 figures, A&A Letter special issue, accepted on 07/13/201

HIFI detection of HF in the carbon star envelope IRC +10216

We report the detection of emission in the J=1-0 rotational transition of hydrogen fluoride (HF), together with observations of the J=1-0 to J=3-2 rotational lines of H35Cl and H37Cl, towards the envelope of the carbon star IRC +10216. High-sensitivity, high-spectral resolution observations have been carried out with the HIFI instrument on board Herschel, allowing us to resolve the line profiles and providing insights into the spatial distribution of the emission. Our interpretation of the observations, with the use of radiative transfer calculations, indicates that both HF and HCl are formed in the inner regions of the envelope close to the AGB star. Thermochemical equilibrium calculations predict HF and HCl to be the major reservoirs of fluorine and chlorine in the atmospheres of AGB stars. The abundances relative to H2 derived for HF and HCl, 8e-9 and 1e-7 respectively, are substantially lower than those predicted by thermochemical equilibrium, indicating that F and Cl are likely affected by significant depletion onto dust grains, although some chlorine may be in the form of atomic Cl. The H35Cl/H37Cl abundance ratio is 3.3 +/- 0.3. The low abundance derived for HF in IRC +10216 makes it likely that the fluorine abundance is not enhanced over the solar value by nucleosynthesis in the AGB star, although this conclusion may not be robust because the HF abundance we derive is a lower limit to the elemental abundance of F. These observations suggest that both HF and HCl should be detectable through low J rotational transitions in other evolved stars.Comment: Accepted for publication in A&A Letter