Richard Gáborjányi

Detection of cereal viruses in wheat ( Triticum aestivum L.) by serological and molecular methods

The reliable monitoring of field virus infections of crop species is important for both farmers and plant breeders. The aim of this study was to detect virus infections of winter wheat in the 2006/2007 season. Twelve well-known winter wheat varieties were sown on two different dates (11 th of October and 3 rd of November 2006). Leaves of two individuals from each genotype were collected on 23rd of April 2007 to detect the virus infections ( Barley stripe mosaic virus — BSMV, Barley yellow dwarf virus — BYDV-PAV, Wheat dwarf virus — WDV and Wheat streak mosaic virus — WSMV) after an extra mild autumn- and wintertime. Virus infections were detected by enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). The aphid-transmitted BYDV-PAV was found frequently whereas other viruses were presented very rarely or were not detected. Forty-six per cent of the tested wheat plants proved to be infected by BYDV-PAV in ELISA, while using PCR, the virus infections with BYDV-PAV was found in 58% o...

Alterations of NADPH: protochlorophyllide oxidoreductase quantity and lipid composition in etiolated barley seedlings infected by Barley stripe mosaic virus (BSMV)

SUMMARY To understand the phenomenon by which infection of seed-transmitted Barley stripe mosaic virus (BSMV) alters membrane structures and inhibits protochlorophyllide biosynthesis of dark-grown barley (Hordeum vulgare L.) plants, we analysed the presence of NADPH:protochlorophyllide oxidoreductase (POR, EC 1.3.1.33) and the galactolipid content and fatty acid composition. The amount of POR in etioplasts of infected leaves, compared with non-infected leaves, was reduced, as measured by immunoelectron microscopy and Western blot. These results are in agreement with the previously described reduction of the ratio of the photoactive 650 nm to non-photoactive 630 nm absorbing protochlorophyllide forms (Harsányi et al., 2002. Physiol. Plant 114, 149-155). The galactolipid content was lower in infected leaves. Monogalactosyl-diacylglycerol (MGDG) content was reduced to 40% and digalactosyl-diacylglycerol to 55% of control plants on a fresh weight basis. In infected plants, the proportion of linolenic acid decreased in both galactolipids. The lower amount of highly unsaturated fatty acids and the reduced abundance of MGDG correlated well with the previously detected reduction in the membrane ratio of prolamellar body (PLB) to prothylakoid (Harsányi et al., 2002. Physiol. Plant 114, 149-155). The reduced amount of POR and the above described alterations in the lipid composition resulted in a disturbed structure of PLBs. As a consequence, pigment synthesis and the greening process were inhibited in infected cells, in turn explaining the appearance of chlorotic stripes of BSMV-infected barley leaves. Our results show that BSMV infection can be detected at a very early stage of leaf development.

Virus infection of ornamental plants in Hungary

Recently the economic importance of the ornamental plant production has shown remarkable growth. Following the countrys joint to the EU increased competition has become characteristic of the Hungarian market. More than 20 viruses have been isolated in the various vegetatively propagated Petunia species and varieties [Richert (1992), Lesemann and Dalchow (1995), Bellardi et al. (1996), Mavric et al. (1996) Salamon (1996), Richert-POggeler and Shepherd (1997), Feldhof et al. (1998), Boonham et al. (1999), Alexandre et al. (2000)]. Metelik et al. (1994, 1996), Mokrd and Gfitzovd (1994), Lesemann and Winter (2002) as well as Pham et al., (2002) examined the health condition of Zanthedeschia aetiopica and other Zanthedeschia species. The presence of Bean yellow mosaic virus (BYMV), Dasheen mosaic virus (DsMV), Cucumber mosaic virus (CMV), Konjac mosaic virus (KoMV) and Tomato spotted wilt vims (TSVW) were detected. Hosta virus X (HVX) and Impatiens necrotic spot vims (INSV) were isolated in the examined Hosta species (Lockhart 2002). Lockhart et al. (2002) verified the presence of Turnip mosaic virus (TuMV) in Heuchera samples and that of Alfalfa mosaic vims (AIMV) in Pulmonaria species. The goal of our work was to make a virological survey of herbaceous ornamental plants in Hungary.

The role of allelopathy in host-virus relations

Introduction The term allelopathy was introduced by Molish (1937) at the first time. Earlier it was considered as a type of interference among higher plants, where products of secondary metabolism inhibit (less promote) the development and physiological processes of neighbourhood plants (Rice 1984). The term allelopathy has been extended recently, including not only plant-plant, but also plant microorganism interactions. It is considered as a new alternative way for biological weed control (Duke et al. 2002, Dikic et al. 2003), in order to reduce environmental pollution (Nemeth Konda 2003). Plant viruses make up about 15-30% out of the whole plant diseases. Virus particles create extremely close biological units with the host cell. The biosynthesis of viruses is done by the organelles of the host cell. Therefore chemical protection against viruses is unsuccesful in vivo and causes the death of the host plant cell at the same time. In spite of this, some natural substances are known to inhibit the replication and cellto cell movement of viruses and to reduce virus concentration (Moraes et al. 1974, Baranwal and Verma 1997, Manickam and Rajappan 1998, Vivanco et al. 1999). The mode of action of natural substances is not yet known exactly, but it can be presumed, that these substances may modify special receptor places on the plant cell surface, therefore adhesion of virus particles can not be happened (Gaborjanyi and Tobias 1986). The aim of our investigations was to study the effect of allelopathic weed extracts on host-vims relations.

Virus–virus interactions

Over the past quarter century there have been massive applications of new molecular, cell biology, and genetics techniques to research plant viruses. Hundreds of complete virus genomes were sequenced and analyzed, their constituent genes and control elements identified, and similarities and differences revealed in genome organization, allowing for the taxonomic classification of viruses. Numerous virus replication systems were described and some viral replicases isolated. Especially good progress was made in understanding cell-to-cell and long-distance viral transport within plants; in cloning dominant and recessive plant genes controlling virus resistances and identifying the cognate viral avirulence factors; in unraveling mechanisms of viral transmission by invertebrate and plasmodiophorid vectors; and in showing, through these advances, how viruses utilize and subvert endogenous eukaryotic processes. The discovery of gene silencing and viral silencing–suppressor proteins transformed thinking about how virus replication is controlled and explained the phenomena of recovery from disease, cross protection, and synergy between unrelated viruses. Transgenic, virus-resistant plants were created and tested successfully in field conditions, and a few were commercialized. Factors underlying the appearance of new disease epidemics were identified. Genetic recombination was reported and found to make an important contribution to generating virus variation. Additionally, some major viral evolutionary pathways were identifed through comparative genome analysis. The stage is set for further major advances in the coming decades.

General properties of grapevine viruses occurring in Hungary

The past fifty years important advances have been made in the field of grapevine virus research, including characterization of pathogens and control measurements. Still the occurrence of Grapevine fanleaf virus (GFLV), Arabis mosaic virus (ArMV), Tomato black ring virus (TBRV), Grapevine chrome mosaic virus (GCMV), Alfalfa mosaic virus (AMV), Grapevine Bulgarian latent virus (GBLV), Grapevine fleck virus (GFkV), Grapevine leafroll- associated viruses (GLRaV1-4), Grapevine virus A (GVA), Grapevine virus B (GVB) and Grapevine rupestris stem pitting- associated virus (GRSPaV) have been reported in Hungary and characterized by conventional methods as woody indexing, herbaceous indexing and serological methods. Among grapevine viruses the Grapevine line pattern virus (GLPV) seems to be uncial; because it was reported only in Hungary. Causal agents of several grapevine diseases, like enation, vein necrosis and vein mosaic remained undiscovered. These virus-like diseases occurred only sporadically, without economic importance.

Herbicide-Affected Plant Metabolism Reduces Virus Propagation

Abstract It has been previously shown that certain herbicides or plant extracts inhibited the viral infection. The goal of this study was to investigate the effect of Obuda pepper virus (ObPV) infection and herbicide or plant extract treatments on the photosynthetic processes of the host plants to get informations about the interactions of these factors. In Capsicum annuum- ObPV host-virus relations the virus infection slightly increased the activity of photosystem II (PSII), as it was supposed from fluorescence induction parameters. Chlorophyll content of leaves was also elevated probably due to virus-induced growth inhibition. The herbicide Stomp (active ingredient: pendimethalin) incorporated into the soil one week before planting (preplant treatment) together with virus infection even strengthened these effects in agreement with previous observations that this herbicide always did not prevent virus infection or reduce virus concentration in hosts. In ObPV-infected Nicotiana tabacum the structural changes showed similar tendency like in ObPV-infected C. annuum, but PSII efficiency did not significantly differ from that of the control. However, non-photochemical quenching (NPQ) increased because of the strongly decreasing CO2 fixation activity. Though simultaneous application of a water extract of Cirsium arvense shoot caused a little stronger inhibition of CO2 fixation, little loss in production was obtained due to significant reduction in virus concentration. In Solanum nigrum-ObPV relation the slightly increasing tendency of the values of actual PSII quantum efficiency could be related to the probably elevated ratio of reaction centre components (increased chlorophyll a/b ratio) in the thylakoids. Application of the herbicide Fusilade S (active ingredient: fluazifop-P-butyl) at 4-6 leaf stage as a postemergence treatment practically prevented systemic virus infection and the virus-induced changes of photosynthesis are probably due to inhibiting the virus infection/replication process.

Pathogen affected greening process of barley seedlings infected with BSMV by seed transmission

The effect of Barley stripe mosaic virus (BSMV) infection was studied on the ultrastructure of etioplasts and the greening process of barley (Hordeum vulgare cv. Pannonia) plants infected by seed transmission. The leaves of 7-11-day old etiolated seedlings were examined with transmission electron microscopy and absorption spectroscopy. The etioplasts of infected seedlings contained smaller prolamellar bodies with less regular membrane structure while prothylakoid content was higher than in the control. Characteristic effect was observed in the process of the Shibata-shift: 40 min delay was observed in the infected leaves. The results of this work proved that BSMV infection significantly delays or inhibits the plastid development and the formation of photosynthetic apparatus.

Epidemyology of tomato pathogen viruses in Hungary

Introduction Tomato (Lycopersicon esculentum) is an important crop on the basis of its high consumption, nutritional and cash value in temperate and tropical countries. Tomato crop production is over 4 million ha and about 110 million tonne on the world. The largest producers are in Asia because the half of the cultivation area and also the production are in these countries. In the European countries tomato is produced mainly under greenhouse. The gene centres is in the regions of the Andes in Peru, Ecuador and Chile. The cultivated tomato is a member of the Lycopersicon genus in the Solanaceae family. After the molecular characterization of Lycopersicon genus were transferred to Solanum (Marshall et al. 2001). Wild Lycopersicon species can be used in resistance breeding (Alexander and Hoover 1955). Six members (L. pimpinellifolium, L. chesmanii, L. parviflorum, L. chmielewski, L. hirsutum and L. penelii) from the Lycopersicon genus could relatively easily cross with cultivated tomato. This species could be use as sources of insect and disease resistance (Rick 1979; Taylor 1986; Tigchelar 1986; Kegler and Friedt 1993). There are about forty different viruses species are infecting Solanaceous vegetable crops, or potato (Solanum tuberosum) and tobacco (Nicotiana tabacum). Among them Potato virus Y (PVY), Tomato spotted wilt virus (TSWV) and other different Tobamoviruses (e.g. Tobacco mosaic virus) can cause severe yield losses. Pepino mosaic virus (PepMV) is a recently emerged viral pathogen in Hungary. It was first reported from pepino (Solanum muricatum) plants from Peru (Jones 1980). The PepMV has several hosts in different plant families (e.g. Amaranthaceae, Solanaceae). The virus is easily mechanically transmitted. PepMV transmitted by workers touching infected plants, and can also transmit by contact between plants. Maybe it is carried in tomato seeds and potentially can also transmit by Bombus bees. The rapid spread of PepMV was reported from European tomato cultivars in the last years (Verhoven et al. 2003). In Hungary PepMV was found first in 2004 from a glasshouse between the area Danube and Tisza Rivers (Forray et al. 2004).

Virus-induced physiologic changes in plants

Numerous investigations of crops infected by viruses have been, and continue to be, conducted on both the physiologic and biochemical levels. Pathologic processes have been discussed on the basis of their biochemical and physiologic mechanisms, such as their effects on photosynthetic processes, respiration, nucleic acid and protein synthesis, hypersensitivity reactions, phytohormones, nutrient transport, and cell wall and intracellular membrane structures.