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As the depth of soil petroleum contamination can vary substantially under field conditions, a rhizotron experiment was performed to investigate the influence of endophyte,P. indica, on maize growth and degradation of petroleum components in a shallow and a deep-reaching subsurface layer of a soil. For control, a treatment without soil contamination was also included. The degree in contamination and the depth to which it extended had a strong effect on the growth of the plant roots. Contaminated soil layers severely inhibited root growth thus many roots preferred to bypass the shallow contaminated layer and grow in the uncontaminated soil. While the length and branching pattern of these roots were similar to those of uncontaminated treatment. Inoculation of maize withP. indicacould improve root distribution and root and shoot growth in all three contamination treatments. This inoculation also enhanced petroleum degradation in soil, especially in the treatment with deep-reaching contamination, consequently the accumulation of petroleum hydrocarbons (PAHs) in the plant tissues were increased. [ABSTRACT FROM PUBLISHER]

Abstract: Epichloë festucae (Ascomycota) infects the grass Festuca rubra. Infected plants may be more resistant to herbivores and obtain other benefits. The 5109bp dsRNA genome of a virus which infects E. festucae was sequenced, and its incidence in natural populations and transmission were studied. The viral genome has characteristics of the family Totiviridae. Its two ORFs are overlapped by four nucleotides; ORF1 codes a 765 amino acid putative coat protein (CP); ORF2 is in a −1 frameshift with respect to ORF1, and codes a 826 amino acid RNA dependent RNA polymerase (RdRp). This virus, denominated Epichloë festucae virus 1 (EfV1), is closely related to members of the genus Totivirus which infect filamentous fungi, as deduced from phylogenetic analyses of CPs and RdRps. In two natural populations of Epichloë festucae, 36.4% of the isolates were infected by EfV1. The virus was efficiently transmitted to asexual fungal spores. However, when ascospore progeny of matings between virus-free and infected strains was analyzed, it was found that the virus was not transmitted to progeny of sexual spores. [Copyright &y& Elsevier]

Endophytes of the genus Epichloë (Clavicipitaceae, Ascomycota) are systemic symbionts of cool-season grasses. Their interactions with grass hosts may vary between mutualistic and pathogenic depending on the mode of endophyte reproduction. Sexual strains prevent flowering and seed set (choke disease) of the host and can be horizontally transmitted by ascospores, while asexual strains remain asymptomatic and are vertically transmitted through seeds. In Switzerland nearly all plants of Brachypodium sylvaticum (Huds.) P.B. are infected by Epichloeë sylvatica Leuchtmann & Schardl, but choke symptoms arc formed very rarely, and are restricted to particular locations and to a minority of plants at those locations. Earlier research has revealed that F. sylvatica is genetically differentiated into sexual and asexual subpopulations. Given the high level of infection and assuming horizontal transmission of sexual strains, multiple host infections have been predicted. In this study, 25 plants out of 63 examined by isozyme analysis were found to he infected by two or three different endophyte genotypes. In most cases endophyte genotypes appeared to he correlated with the symptom type of a particular tiller, suggesting that the fungal genome controls choke formation and that the sexual and asexual subpopulations are separated at the ramet (tiller) level rather than at the genet (plant) level. These conclusions were further supported by analyses with log-linear models of the population structure of E. sylvatica at four locations where choke symptoms were present. These analyses also revealed a geographic structure in the asexual subpopulation hut not in the sexual subpopulation which could be caused by the different dispersal ranges of their propagules. The rare occurrence of sexually reproducing strains and the dominance of a single genotype in asymptomatic plant populations may be explained by the colonization history of B. sylvaticum and its endophyte in Switzerland. [ABSTRACT FROM AUTHOR]