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Anthracnose disease of cool-season turfgrasses, caused by the fungus Colletotrichum cereale, has recently emerged as one of the most significant pathogens of Poa annua. Here we investigated the utility of four repetitive transposable elements as molecular markers for the analysis of C. cereale populations. Southern blot hybridization analysis revealed lineage-specific polymorphisms and distribution patterns for these transposons. Comparative phylogenetic analysis of three nonrepetitive protein coding DNA sequences against the transposon restriction fragment length polymorphisms indicated that the transposon sequences have similar evolutionary histories to those found in the sampled C. cereale population, despite the alteration of several transposon copies by repeat-induced point mutation. The variability and ubiquity of the [Ccret2.sup.A15] transposon in C. cereale genomes suggest that this element could be used as a reliable DNA marker to discriminate between lineages of the fungus, identify hybrid genotypes, and analyze genetic diversity in populations of this turfgrass pathogen.

The suppressive ability of several strains of cyclic lipopeptide-producing Bacillus rhizobacteria to grey leaf spot disease caused by Magnaporthe oryzae has been documented previously; however, the underlying mechanism(s) involved in the induced systemic resistance (ISR) activity in perennial ryegrass ( Lolium perenne L.) remains unknown. Root-drench application of solid-phase extraction ( SPE)-enriched surfactin and live cells of mutant Bacillus amyloliquefaciens strain FZB42-AK3 (produces surfactin, but not bacillomycin D and fengycin) significantly reduced disease incidence and severity on perennial ryegrass. The application of the treatments revealed a pronounced multilayered ISR defence response activation via timely and enhanced accumulation of hydrogen peroxide ( H2O2), elevated cell wall/apoplastic peroxidase activity, and deposition of callose and phenolic/polyphenolic compounds underneath the fungal appressoria in naïve leaves, which was significantly more intense in treated plants than in mock-treated controls. Moreover, a hypersensitive response ( HR)-type reaction and enhanced expression of LpPrx (Prx, peroxidase), LpOXO4 (OXO, oxalate oxidase), LpPAL (PAL, phenylalanine ammonia lyase), LpLOXa (LOX, lipoxygenase), LpTHb (putative defensin) and LpDEFa (DEFa, putative defensin) in perennial ryegrass were associated with SPE-enriched surfactin and live AK3 cell treatments, acting as a second layer of defence when pre-invasive defence responses failed. The results indicate that ISR activity following surfactin perception may sensitize H2O2-mediated defence responses, thereby providing perennial ryegrass with enhanced protection against M. oryzae. [ABSTRACT FROM AUTHOR]