Fungi infecting cultivated moss can also cause diseases in crop plants

Bryophytes (mosses) are non‐vascular plants inhabited by a large number of fungal species, but whether mosses can act as reservoirs of fungal pathogens of crop plants has gained little attention. A few moss species including the Sunagoke moss (Racomitrium japonicum; family Grimmiaceae) are found to have modern economical applications in uses such as greening of urban environments. In a previous study, we identified fungi causing symptoms of varying severity in the commercially grown Sunagoke moss. The aim of this study was to test whether the same fungal isolates are pathogenic to vascular plants. An isolate of Fusarium avenaceum lethal to the Sunagoke moss caused root and crown rot in barley (Hordeum vulgare) and reduced germination of tomato (Solanum lycopersicum) and carrot (Daucus carota) grown in the infested soil. An isolate of Cladosporium oxysporum causing mild symptoms in moss reduced growth and caused reddening and premature death of carrot seedlings. On the other hand, isolates of Alternaria alternata and Fusarium oxysporum lethal to the Sunagoke moss caused no detectable symptoms in any tested vascular plant, suggesting specialisation of these isolates to moss. Chloroplast repositioning was observed in the neighbouring cells towards the initially infected cell following infection with F. avenaceum and A. alternata in Physcomitrella patens (family Funariaceae), a model moss used to study microscopic symptoms. Infection of P. patens with a non‐virulent Apiospora montagnei isolate induced formation of papillae in the moss cells, indicating activation of host defence as described in vascular plants. Results suggest that mosses and vascular plants may be linked by a common microbial interface constituted by pathogenic fungi. The findings have epidemiological implications that have gained little previous attention.     

Effect of age of growing turkeys on nutrient digestibility and energy value of cereal-soybean-based diets

Ileal and total tract digestibility of protein, total tract digestibility of fat and AMEN of cereal-based diets were assayed in growing turkeys at four, seven and 12 weeks of age. Fat digestibility and AMEN improved linearly with age. Total tract protein digestibility improved with age according to a curvilinear trend, while ileal protein digestibility improved from 4-7 weeks of age but decreased from 7-12 weeks of age. It can be concluded that higher AMEN values could be applied when formulating diets for older than for younger turkeys. Regarding protein digestibility more investigation is needed but a possible fall in values after the first weeks of age may be expected.     

Bile acid amidoalcohols: simple organogelators

Simple bile acid amide synthesis of lithocholic and deoxycholic acids with 2-aminoethanol and 3-aminopropanol are reported. The structural properties of these amides were examined by NMR spectroscopic, ESI-TOF mass spectral, and X-ray crystallographic methods. The gelation properties of these amides in common organic solvents and in three different water solutions were also investigated using Tyndall effect, SEM, TEM, and optical microscopy. 2-Hydroxyethylamides were found to be effective gelators in chlorinated organic solvents and 3-hydroxypropylamides in aromatic solvents. Both derivatives thicken neutral and acidic water solutions.     

Cryopreservation of in vitro-grown shoot tips of raspberry (Rubus idaeus L.) by encapsulation–vitrification and encapsulation–dehydration

The first efficient cryopreservation procedure for in vitro-grown shoot tips of raspberry (Rubus idaeus L.) has been developed based on encapsulation–vitrification (EnVi) and encapsulation–dehydration (EnDe). EnVi resulted in higher survival (85%) and regrowth (75%) of cryopreserved shoot tips than EnDe (65 and 50%, respectively). In both cryogenic procedures, shoots regenerated from cryopreserved shoot tips without intermediary callus formation. Histological studies showed that a much larger number of meristematic cells survived following EnVi than EnDe. The EnVi procedure was applied to seven raspberry genotypes with an average survival and regrowth of 71 and 68%, respectively. Regenerated plants showed normal morphology. Results here indicate EnVi as a simple and efficient method for long-term preservation of R. idaeus germplasm.     

Viral genome-linked protein (VPg) controls accumulation and phloem-loading of a potyvirus in inoculated potato leaves

The viral protein covalently linked to the 5' end of the plus-sense, single-stranded RNA genome of potyviruses (genus Potyvirus) can be an avirulence determinant in incompatible potyvirus-host combinations in which the resistance prevents systemic virus infection. The mechanism is not well known. This study shows that virus strain-specific resistance to systemic infection with Potato virus A (PVA) in Solanum commersonii is overcome by a single amino acid (aa) substitution, His118Tyr, in the viral genome-linked protein (VPg). Virus localization and other experiments revealed that Tyr118, controls phloem loading of PVA. The critical boundary may be constituted in phloem parenchyma, companion cells, or both. Tyr118 also controls the cellular level of virus accumulation in infected leaves, including phloem cells. Amino acid substitutions at three additional positions of the central part (aa 116) and C terminus (aa 185) of the VPg and of the N terminus of the 6K2 protein (aa 5) affect virus accumulation and rate of systemic infection but are not sufficient for phloem loading of PVA. These data, together with previous studies, indicate that the PVA VPg aa residues crucial for systemic infection are host specific. Also, our data and previous studies on other potyvirus-host species combinations indicate that the central part of the VPg is a domain with universal importance to virus-host interactions required for systemic invasion of plants with potyviruses.     

Potato gene Y-1 is an N gene homolog that confers cell death upon infection with potato virus Y

ADG2 is a DNA sequence mapped to a resistance (R) gene-rich region at the distal end of chromosome XI in potato (Solanum tuberosum subsp. andigena). The gene, in which ADG2 represents the predicted nucleotide-binding domain (NBS), was cloned and characterized. The coding region of the gene (designated as Y-1) is 6,187 bp long and structurally similar to gene N that confers hypersensitive resistance to Tobacco mosaic virus in Nicotiana spp. Both belong to the TIR-NBS-LRR class of genes and show 57% identity at the amino acid sequence level. The introns of Y-1 were spliced as predicted from the sequence. Y-1 cosegregated with Ry(adg), a gene for extreme resistance to Potato virus Y (PVY) on chromosome XI, as tested in a potato-mapping population and with independent potato cultivars. Leaves of the transgenic potato plants expressing Y-1 under the control of Cauliflower mosaic virus 35S promoter developed necrotic lesions upon infection with PVY, but no significant resistance was observed, and plants were systemically infected with PVY.     

Detection of the potyviral genome-linked protein VPg in virions and its phosphorylation by host kinases

The multifunctional genome-linked protein (VPg) of Potato virus A (PVA; genus Potyvirus) was found to be phosphorylated as a part of the virus particle by a cellular kinase activity from tobacco. Immunoprecipitation, immunolabeling, and immunoelectron microscopy experiments showed that VPg is exposed at one end of the virion and it is accessible to protein-protein interactions. Substitution Ser185Leu at the C-proximal part of VPg reduces accumulation of PVA in inoculated leaves of the wild potato species Solanum commersonii and delays systemic infection, which is not observed in tobacco plants. Our data show that kinases of S. commersonii differentially recognize the VPg containing Ser or Leu at position 185, whereas both forms of VPg are similarly recognized by tobacco kinases. Taken together, our data imply that the virion-bound VPg may interact with host proteins and that phosphorylation of VPg may play a role in the VPg-mediated functions during the infection cycle of potyviruses.     

Electrophoretic methods for fractionation of native and heat-denatured bovine beta-lactoglobulin

We have developed three electrophoretic methods for analytical and preparative separation of native and heat-denatured beta-lactoglobulin. The methods can be applied, e.g., to optimize dairy milk processing, especially in laboratories which are not provided with expensive column chromatographic instruments. The methods consist of native PAGE followed by electroelution. Consequently, the eluted proteins are in solution in a biologically active and native form, and can therefore be used immediately for further analyses. This revised version was published online in July 2006 with corrections to the Cover Date.