Local maladaptation of the anther-smut fungus parasitizing Dianthus carthusianorum

Pathogens are generally expected to evolve faster than their hosts and are therefore likely to be locally adapted. However, some pathogens might lag behind in the co-evolutionary arms race because they do not have some of the advantages shared by most other pathogens (e.g., high mutation or recombination rates, short generation time, high dispersal ability). This is the case of Microbotryum fungi that cause the anther smut disease in plants of the family Caryophyllaceae. We investigated the patterns of local adaptation and maladaptation in Microbotryum carthusianorum and its host plant Dianthus carthusianorum. We performed a full cross-inoculation experiment using half-sib plant families and fungal samples originating from three naturally infected populations in the Czech Republic. We specifically asked, which components of pathogen fitness (i.e., infectivity and host manipulation) are affected by local (mal)adaptation. The pathogen was on average 1.6 times more successful in infecting plants from foreign populations compared to plants from its home population. Once the infection was successful, the pathogen accelerated the plant’s flowering and thus increased the opportunity for transmission to new hosts. However, the level of manipulation of host flowering did not differ between home and foreign populations. This study showed that the pathogen’s infectivity followed a clear pattern of local maladaptation, whereas the host manipulation did not. Our study taken together with previous studies of a related anther smut species reveals the pervasiveness of local maladaptation in this group of pathogens that arises as the result of their restricted gene flow and reduced recombination rates.

     

Utilization of isozyme polymorphism for cultivar identification of 45 commercial peas (Pisum sativum L.)

Forty five Pisum sativum cultivars were analysed by isozyme electrophoresis with the objective to find protein markers for exact and reproducible discrimination of individual genotypes. The combination of six enzyme systems (acid phosphatase, amylase, esterase, leucine aminopeptidase, shikimate dehydrogenase and phosphoglucomutase) with two electrophoretic techniques (NATIVE-PAGE, isoelectric focusing) and use of seed and leaf tissue enabled to identify all 45 studied cultivars. Critical factors which may affect utilization of isozyme electrophoresis for commercial applications in pea breeding and seed production and testing are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Stripping Fecundity of Common Bream (Abramis brama L.) from the Rivers Trent and Sow (Nottinghamshire, UK)

Results obtained with common bream (Abramis brama) originating from the rivers Trent and Sow (Great Britain) are presented with particular attention to the egg size and absolute and relative fecundity recorded during stripping of hormonally (pituitary extract) treated females. The average number of eggs obtained by stripping 1 kg of female biomass (RSF) from the river Sow and Trent were 93,642 ± 20,896 and 151,179 ± 25,123, respectively. These values were similar to the respective parameters in bream populations from north-western USSR lakes.