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The objectives of this study were to identify stable and high-yielding genotypes grown in organically managed fields in Latvia and Estonia and to determine their canopy parameters and susceptibility to seed-borne diseases. Field trials with barley (Hordeum vulgare L.) were conducted using 26 varieties and breeding lines including 20 covered and six hulless genotypes at three locations over three growing seasons. Estonian breeding line 4533.4.3.6 yielded significantly above the average (3.99 t ha–1; LSD = 0.230 t ha–1) and showed wide adaptability as indicated by the coefficient of regression (bi = 1.05), relatively small deviation from regression (s2d = 0.04) and one of the lowest value of ecovalence (Wi = 1.41%). There were significant differences between genotypes according to the canopy parameters measured, such as growth type, early vigour, crop ground cover and canopy height. High-yielding barley genotypes were characterized by more planophile growth habit and shorter canopy height, thus providing good ground cover in the early stages of plant growth. Rasa was the only variety found to have no plants infected with loose smut or leaf stripe, in either of the locations. [ABSTRACT FROM AUTHOR]

Five species ofPenicillium(Penicillium chrysogenum, P. funiculosum,P. griseofulvum,P. implicatumandP. oxalicum) are implicated in seed-borne diseases. Here, we report the discovery of molecular markers based on the internal transcribed spacer regions of fungal ribosomal DNA (rDNA), which are described as primary DNA barcode markers of fungi, for rapid diagnosis and early detection ofPenicilliumspp. The present markers are expected to be useful for the prevention of seedling and systemic plant diseases associated withPenicilliumspp. Our findings, which provide valuable insights into the taxonomy ofPenicilliumspp., should contribute to improve safety of agricultural produce, thereby protecting both humans and animals from harmful food contaminants such as mycotoxins. In addition, we examined the cellular fatty acid composition of five species ofPenicillium. The species studied were found to possess similar fatty acid composition; however, they differed in terms of relative concentration. The principal fatty acids were oleic acid (C18:1) and linoleic acid (C18:2), comprising 80% or more of the total fatty acid composition of these species. These fatty acid profiles may be useful for characterization and identification of fungi. Data derived from the present study highlight the importance of using polyphasic methods for accurate species-level identification ofPenicillium. [ABSTRACT FROM PUBLISHER]

Cucumber angular leaf spot, caused byPseudomonas syringaepv.lachrymans(Psl), is one of the most devastating bacterial diseases in cucumber worldwide. Seedborne transmission of the pathogen is one of the principal modes for disease spread. To date, the detection ofPslis mainly achieved by culture methods, which are time and labour-consuming. In the present work, propidium monoazide (PMA) treatment combined with a quantitative real-time PCR (PMA-qPCR) assay was developed for quantifying viablePslcells in contaminated cucumber seeds. PMA selectively penetrates compromised membranes of dead cells and inhibits DNA amplification during real-time PCR. The primers, based on a 162-bp amplicon fromgap1gene, were highly specific forPslat the species level. PMA at 60 μmol L−1was suitable for selective quantification of viable cells. The limit of detection (LOD) of PMA-qPCR for detecting viable cells in bacterial suspension and artificially contaminated cucumber seeds was 3.25 × 102CFU·mL−1and 47.73 CFU·g−1, respectively. For naturally contaminated seeds, quantifiable levels of viable cells were observed in eight out of the 37 samples, and ranged from 103to 104CFU·g−1. This assay has been confirmed to be a rapid and selective method to quantify the viable cells ofPslin bacterial suspension and cucumber seeds. Application of the assay may potentially improve pathogen control and disease management. [ABSTRACT FROM PUBLISHER]

Aflatoxins are carcinogenic metabolites produced byAspergillus flavus. Rice seeds may be contaminated by it at the time of harvesting or during storage. Detection of aflatoxigenic strains by TLC and analysis of genetic variability among 50A. flavuscultures from seeds of various rice genotypes by PCR using 18 RAPD primers is reported here. About 58% isolates were aflatoxigenic whereas 42% were non-toxic. There were 246 bands and 48 haplotypes. Approximately 99% bands were polymorphic, and thus high degree of genetic variability was observed. All the primers were informative with PIC values of range 0.75–0.95. Seventeen RAPD markers were not found to be useful for the detection of aflatoxigenicA. flavus. However, one RAPD primer 3B could differentiate aflatoxigenic and non-toxigenic isolates to some extent. One allele of Primer 3B at approximately 480 bp was present in 85% aflatoxin non-producers and in 6% aflatoxigenic isolates. This information may be utilised for designing markers for differentiating toxic/non-toxic isolates ofA. flavus. [ABSTRACT FROM AUTHOR]

In this study, we considered the efficacy of seed treatments for the inactivation of some seedborne viruses in tomato, pepper, melon, squash, bean and lettuce seeds, which are essential for human nutrition and seed production in our country. A total of 325 seed samples obtained from various farmers and foundations were tested by DAS-ELISA and RT-PCR procedures. Eight seed lots infected with Tomato mosaic tobamovirus (ToMV), Tobacco mosaic tobamovirus (TMV), Cucumber mosaic cucumovirus (CMV), Soybean mosaic potyvirus (SMV) and Lettuce mosaic potyvirus (LMV) were selected as research materials. Virus inactivation treatments were made by using acetic acid (CH3COOH), hydrogen peroxide (H2O2), hydrochloric acid (HCl), sodium hypochlorite (NaClO), Triton X 100, dry heat, heated water, ozone (O3), and UV (305 nm wavelength). The most effective treatments for reducing virus concentration were HCl, heated water (65 °C) and ozone (10 g m−3). These treatments reduced concentrations of seed-borne viruses in ranges of 51%, 42%, and 32%, respectively. Other treatments were less effective and reduced virus concentrations in the range of 27%–12%. HCl and ozone treatments were the most effective and applicable methods because they did not have negative effect on seed germination. [ABSTRACT FROM AUTHOR]

The study was conducted to assess the impact of natural seed-borne inoculum levels ofBipolaris sorokinianaon seedling emergence and growth, seedling blight and the early establishment of foliar blight in field. Three levels of seed-borne inoculum (11, 19 and 29%) of one cultivar (Sonalika) and four levels of seed-borne inoculum (5, 35, 65 and 95%) of two wheat cultivars (Sonalika and BL 1473) were evaluated in 2002 and 2003 field experiments, respectively. Seedling vigour study was conducted in the greenhouse in 2003. Seed-borne inoculum levels higher than 35% reduced seedling emergence and seedling vigour substantially, and also increased the seedling blight indicating that the seed-borne inoculum ofB.sorokinianaplayed a crucial role in seedling health and early establishment of the pathogen on wheat. The findings will help to reduce the inoculum pressure of spot blotch and common root rot on wheat. [ABSTRACT FROM AUTHOR]

Rauwolfia serpentinais an important medicinal herb. Studies were conducted to determine causal organisms of foliar diseases inR. serpentinain Bhadra Wildlife Sanctuary during 2006–2009. The foliar disease incidence and its distribution and disease severity in nine state forest regions of the sanctuary were determined. The seedborne nature and transmission of the causal organism was also determined. The management of seedborne inoculum was done by seed dressing with fungicides. The effect of foliage infection on secondary metabolite content was also determined. Results of the present study indicated thatCercospora rauwolfiaeis major leaf spot disease causing pathogen. The disease is homogeneously distributed through the study area. The foliar disease severity was high in Kagemanegiri forest during October–November. The minor leaf spot disease caused byAlternaria alternataoccurred occasionally.Alternaria alternatais seedborne and seed transmitted and could be managed by seed treatment with Captra or Hyzeb. The secondary metabolites like alkaloids and steroids decreased with increase in foliar infection byC. rauwolfiae, while phenol and flavonoid contents increased. The study suggested thatR. serpentinais affected in wild byC. rauwolfiaeandA. alternata. The latter pathogen is seedborne and seed transmitted and controlled by seed treatment. [ABSTRACT FROM PUBLISHER]

The effect of plant essential oils,Solanum chilenseandAster sedifoliusraw saponins, plant-derived colourants andBrassica carinataglucosinolate-containing tissues, for the control of seedborne fungiAlternaria dauci,Alternaria radicina,Colletotrichum lindemuthianumandAscochyta rabiei, was evaluated.In vitroassays indicated that oregano essential oil, bark chestnut-derived colourant andB. carinatameals, showed a large spectrum of activity against all pathogens.S. chilenseraw saponins were effective againstA. dauciandA. radicina, while those fromA. sedifoliusalso inhibited significantlyC. lindemuthianum. Screening showed the antifungal potential of natural compounds. [ABSTRACT FROM PUBLISHER]

Seed mycoflora associated with wheat was studied on different media with a particular reference to Blotter and potato dextrose agar (PDA) procedures of ISTA. Seed-borne fungi,viz. Fusarium moniliforme, Rhizopusspp.,Mucorspp.,Alternaria alternata, Aspergillus niger, Aspergillus flavus, Curvularia lunata, Drechsleraspp,Alternariaspp. andPenicilliumspp., were isolated from the variety HD264. Blotter method was found to be the best media for the isolation of mycoflora whether borne externally or internally. Total number and frequency of occurrence of fungi were recorded. The effect of seed treatment with different chemicals and eco-friendly botanicals was analysed on germination, and growth, better percentage of seed germination and reduction in fungal pathogen were due to biochemical seed treatment. [ABSTRACT FROM PUBLISHER]

Seed sample of lentil collected from the Swabi district were treated with NaCl and KCl at 0.01, 0.1 and 1.0% (w/w). Seed-borne mycoflora was observed at 0, 20, 40, 60 and 80 day intervals. Seed treatment with both the salts was found to be effective against storage fungi; however, KCl was more efficient against storage mycoflora such as Aspergillus species when compared with NaCl. With the passage of time, the incidence of deep-seated fungi was observed in salt-treated seed samples while untreated seed sample showed heavy infestation by the species of Aspergillus. Seed viability also remained unaffected in storage, except in seeds heavily infested with seed-borne mycoflora. Aspergillus spp. were the main cause of seed rot. Surface sterilisation of seeds with 1% Na(OCl)2 reduced the fungal infestation of seeds. Among various concentrations of salts, 0.1% (w/w) of both salts were better in controlling seed-borne mycoflora. [ABSTRACT FROM AUTHOR]

Seed samples of okra (Abelmoschus esculentus (L.) Moench) variety Arka anamika were subjected to hot water treatment at 42, 52 and 62°C for a period of 30 min and UV light treatment for 10, 20, 30 min at 28 ± 2°C. Their efficacy was tested against some seedborne fungal species. Among them, seeds under hot water treatment at 52°C for 30 min and UV light at 20 min were found to be more effective in the improvement of crop, both in greenhouse and field conditions. Ultimately, there was increase in the total number of leaves, fruits, length of the fruit, girth and biomass of the plants. Apart from these the total number of seeds per fruit, 1000 seed weight and ascorbic acid content were also found to be enhanced. These treatments also reduced the incidence of mycoflora in the seeds and thereby enhanced the seed germination percentage and vigour index of the seedlings. [ABSTRACT FROM PUBLISHER]

The article presents a study on the effects of seedborne infection on anthracnose development in AC Ole pinto bean and Navigator navy bean. It states that the study used surface-sterilized seed which were placed in an incubator for determining the germination rates and percentage of seed infection. The study showed that seedborne infection resulted to yield losses of 20% in AC Ole pinto bean and 27% Navigator navy bean, and that low rates of infection can produce severe anthracnose development.

The article discusses a study which examined the natural incidence of disease caused by pathogen Pyrenophora (P.) semeniperda on undispersed host seeds of grass Bromus tectorum. The researchers found that at least 90% of undispersed seeds exhibiting the disease were infected after maturity by conidia borne. It concludes that studies on the life history of P. semeniperda and its genetic structure should further clarify the role of seed-assisted dispersal in the ecology of this pathogen.

Reports the mapping of a covered smut resistance gene using a random amplified polymorphic DNA (RAPD) marker OPJ10[sub 450] to the short arm of chromosome 5 (1H). Identification of covered smut of barley as a seed-borne disease; Economic loss resulting from the disease; Plant material and DNA extraction; Mapping of the RAPD marker OPJ10[sub 450].

Survival and biocontrol activity of Clonostachys rosea (isolate IK726) conidia during storage on barley seeds were investigated. The initial density of colony forming conidia on seed was 4 × 10[sup 3] to 9 × 10[sup 4] colony forming units (cfu)/seed. After 5 months storage at 4°C, the density decreased by less than one order of magnitude and the biocontrol efficacy against seedling blight caused by seed-borne Bipolaris sorokiniana was maintained at a significantly high level ( > 80% disease reduction) for > 5 months. Conidial survival on seeds stored at 20°C declined more rapidly than at 4°C, and biocontrol efficacy was significantly reduced after 3–5 months. However, conidia produced on solid media over 20 days survived better than conidia produced in liquid culture and conidia from solid media produced over 12 days. In contrast, when seeds treated with conidia were packed with silica gel and stored at 20°C, the cfu density decreased by less than one order of magnitude after 5 months and the biocontrol efficacy was still high after 6 months. A dose–response curve revealed that 103 cfu/seed were needed for 80% control of seedling blight. Similar control was obtained in storage experiments when approximately 103 cfu/seed were recovered from seed, indicating that conidia which survived also retained a high ability to control disease. [ABSTRACT FROM AUTHOR]