Effects of acid rain treatments on the birch rust,Melampsoridium betulinum and birch,Betula pendula

Effects of acidic rain on birch rust and on the growth of Betula pendula seedlings were studied by irrigating with acidic water at pH 3, 4 and 5.6. The seedlings were inoculated with uredospores of Melampsoridium betulinum and the development of rust and the severity of rust infection was examined. The increasing acidity of the irrigation water did not affect on the development of the rust, but the nitrogen in the acidified water resulted in an extension of seedling growth, and hence the leaves became senescent at a later date in autumn and the rust grew for a longer time.     

Genetic diversity of Dothistroma septosporum in Estonia, Finland and Czech Republic

Dothistroma needle blight is one of the most damaging foliage diseases in pine plantations worldwide. Recently it has become more aggressive in native pine stands in northern America and has been found frequently on Scots pine stands in northern Europe. In Estonia and Finland it was noticed for the first time in 2006 and 2008, respectively and in Central Europe in the late 1990s. We show considerable diversity in allele patterns of several microsatellite loci in populations of these countries which does not support the hypothesis of a recent introduction. We investigated 104 isolates by using eight microsatellite loci. Estonian and Finnish isolates originated from P. sylvestris and those from the Czech Republic from six species of Pinus spp. and Pseudotsuga menziesii. The genetic diversity was considerable in all three populations, and did not differ significantly between populations. The results suggest slight migration from south to north, even if no similar haplotypes were found between any of the populations. Both, the pairwise genetic differentiation and Nei’s genetic distance reflected geographic distances between the populations. Differentiation between the studied populations of D. septosporum was low but statistically significant. Only 6 % of the genetic variation was due to differences between populations. The high haplotypic diversity, low number of identical haplotypes, and low degree of genetic disequilibrium in all investigated populations suggested occurrence of sexual proliferation in this area, although the sexual state of the fungus has not been recorded in Estonia and Finland. The high diversity may suggest a long presence of D. septosporum in northern Europe, or alternatively, its recent introduction as a massive inoculum from an unknown direction.     

Endosperm and aleurone cell structure in barley and wheat as studied by optical and Raman microscopy

Grain ultrastructure is of utmost importance when designing grain processing procedures in the food industry. In this study, wheat and barley grain components were localised using optical and Raman microscopy. The optical microscopic analyses were performed using several selective stains to localise β-glucan, protein and starch or autofluorescence to image the ferulic acid and other fluorescing substances. Alternatively, Raman microscopy was applied to localise the grain components without any need for preceding staining or other sample pretreatment. Both methods provided consistent information on the grain structures, illustrating the distribution of polysaccharides, aromatics and protein in endosperm and aleurone layers. In aleurone layers of both barley and wheat, a distinct difference between the anticlinal and periclinal cell walls was observed. The anticlinal cell walls were enriched with aromatic substances which were present in remarkably lower concentrations in the inner periclinal cell walls but for barley, an even higher concentration in the outer periclinal cell wall was observed. In addition, Raman spectroscopy illustrated the detailed distribution of substances across the aleurone cell walls: β-glucan was adjacent to proteins and it was deficient in the middle lamella whereas arabinoxylan was enriched in the outer cell wall layers and middle lamella.