Elite UK winter wheat cultivars differ in their ability to support the colonization of beneficial root-infecting fungi.

In numerous countries, Gaeumannomyces species, within the Magnaporthaceae family, have previously been implicated in the suppression of take-all root disease in wheat. A UK arable isolate collection (n=47) was gathered and shown to contain Gaeumannomyces hyphopodioides and an unnamed Magnaporthaceae species. A novel seedling pot bioassay revealed that both species had a similar ability to colonize cereal roots; however, rye (Secale cereale) was only poorly colonized by the Magnaporthaceae species. To evaluate the ability of 40 elite UK winter wheat cultivars to support soil inoculum of beneficial soil-dwelling fungi, two field experiments were carried out using a naturally infested arable site in south-east England. The elite cultivars grown in the first wheat situation differed in their ability to support G. hyphopodioides inoculum, measured by colonization on Hereward as the subsequent wheat in a seedling soil core bioassay. In addition, the root colonization ability of G. hyphopodioides was influenced by the choice of the second wheat cultivar. Nine cultivars supported the colonization of the beneficial root fungus. Our findings provide evidence of complex host genotype-G. hyphopodioides interactions occurring under field conditions. This new knowledge could provide an additional soil-based crop genetic management strategy to help combat take-all root disease.

Long-term spatiotemporal stability and dynamic changes in helminth infracommunities of bank voles (Myodes glareolus) in NE Poland.

Parasites are considered to be an important selective force in host evolution but ecological studies of host-parasite systems are usually short-term providing only snap-shots of what may be dynamic systems. We have conducted four surveys of helminths of bank voles at three ecologically similar woodland sites in NE Poland, spaced over a period of 11 years, to assess the relative importance of temporal and spatial effects on helminth infracommunities. Some measures of infracommunity structure maintained relative stability: the rank order of prevalence and abundance of Heligmosomum mixtum, Heligmosomoides glareoli and Mastophorus muris changed little between the four surveys. Other measures changed markedly: dynamic changes were evident in Syphacia petrusewiczi which declined to local extinction, while the capillariid Aonchotheca annulosa first appeared in 2002 and then increased in prevalence and abundance over the remaining three surveys. Some species are therefore dynamic and both introductions and extinctions can be expected in ecological time. At higher taxonomic levels and for derived measures, year and host-age effects and their interactions with site are important. Our surveys emphasize that the site of capture is the major determinant of the species contributing to helminth community structure, providing some predictability in these systems.