Insect Feeding Deterrents in Endophyte-Infected Tall Fescue

The presence of an endophytic fungus, Acremonium coenophialum, in tall fescue (Festuca arundinacea) deterred aphid feeding by Rhopalosiphum padi and Schizaphis graminum. Both species of aphid were unable to survive when confined to endophyte-infected tall fescue plants. Feeding deterrents and toxic factors to R. padi and Oncopeltus fasciatus, large milkweed bug, were primarily associated with a methanol extract obtained when endophyte-infected tall fescue seed was serially extracted with hexane, ethyl acetate, and methanol. The concentrations of pyrrolizidine alkaloids were determined to be 30 to 100 times greater in the methanol extract than in the hexane and ethyl acetate extracts.     

Production of the Tremorgenic Mycotoxins Verruculogen and Fumitremorgin B by Penicillium piscarium Westling

The tremorgenic mycotoxins verruculogen and fumitremorgin B were isolated from Penicillium piscarium Westling. The coexistence of these tremorgens in culture has previously been reported for one other unrelated fungal species, Aspergillus caespitosus Raper and Thom, and lends further support to the suggestion that the tremorgens have a common biosynthetic origin.     

Surrogate transformation of perennial ryegrass, Lolium perenne, using genetically modified Acremonium endophyte.

Summary Conditions have been developed for transforming protoplasts of the perennial ryegrass endophyteAcremonium strain 187BB. Unlike most other ryegrass endophytes, this strain does not produce the lolitrem B neurotoxin and is therefore suitable as a host for surrogate introduction of foreign genes into grasses. Transformation frequencies of 700–800 transformants/g DNA were obtained for both linear and circular forms of pAN7-1, a hygromycin (hph) resistant plasmid. Up to 80% of the linear transformants were stable on further culturing but only 25% of the circular transformants retained hygromycin resistance. Integration of pAN7-1 into the genome was confirmed by Southern blotting and probing of genomic digests of transformant DNA. Both single and tandemly repeated copies of the plasmid were found in the genome and both the number and sites of integration varied among the transformants. At least 13 chromosomes were identified in 187BB using contour-clamped homogeneous electric field (CHEF) gel electrophoresis. Probing of Southern blots of these gels confirmed that pAN7-1 had integrated into different chromosomes. The -glucuronidase (GUS) gene,uidA, was also introduced into 187BB by co-transformation of pNOM-2 with pAN7-1. GUS activity was detected by growing the transformants on plates containing 5-bromo-4-chloro-3-indolyl -D-glucuronic acid and by enzyme assays of mycelial extracts. Severalhph- anduidA-containing transformants were reintroduced into ryegrass seedlings and expression of GUS visualized in vivo, demonstrating that 187BB can be used as a surrogate host to introduce foreign genes into perennial ryegrass. Molecular analysis of fungal isolates from the leaf sheath confirmed that the pattern of pAN7-1 and pNOM-2 hybridizing fragments was identical to that observed in the fungus used as inoculum.     

Studies on the susceptibility ofOryctes rhinoceros to some entomogenous fungi

Cultures ofMetarhizium anisopliae (Metsch.) Sor.,Beauveria bassiana (Bals.) Vuill.,B. tenella (Delac.) Siem.,Aspergillus fumigatus Fres. andPaecilomyces farinosus (Dicks, exFr.) Brown & Smith were tested for pathogenicity toOryctes rhinoceros L. All the long spored cultures ofM. anisopliae isolated fromOryctes spp. were equally pathogenic toO. rhinoceros. Most of the 23 short spored cultures from other insects caused lesions onOryctes larvae but only 5 isolates were lethal. SomeBeauveria isolates caused brown lesions on larvae but generally these larvae developed into normal adults. One isolate ofB. bassiana fromCarpocapsa pomonella L. killed larvae at the time of pupation. Cultures ofA. fumigatus andP. farinosus were not pathogenic. A method for growingM. anisopliae on oats for large scale field use is described.

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Résumé Des cultures deMetarhizium anisopliae, deBeauveria bassiana, deB. tenella, d'Aspergillus fumigatus et dePaecilomyces farinosus ont été examinées en fonction de leurs effets pathogènes surOryctes rhinoceros. Toutes les cultures à spores longues deM. anisopliae isolées desOryctes spp. ont été également pathogènes pourO. rhinoceros. La plupart des 23 cultures à spores courtes obtenues à partir d'autres insectes ont causé des lésions sur les larves d'Oryctes mais cinq seulement ont été mortelles. Certaines souches deBeauveria ont causé des lésions brunes sur les larves mais, en général, ces larves ont donné des adultes normaux. Une culture deB. bassiana isolée deCarpocapsa pomonella a tué les larves au moment de leur métamorphose en chrysalides. Les cultures d'A. fumigatus et deP. farinosus n'ont pas eu d'effet pathogène. Une méthode de culture deM. anisopliae sur avoine pour l'utiliser sur de grandes surfaces est décrite.

     

Isolation and characterization of microsatellite loci in wild and domestic turkeys (Meleagris gallopavo)

We describe the isolation, development and application of seven microsatellite loci in the eastern wild turkey, Meleagris gallopavo silvestris, as well as their amplification and levels of polymorphism in the domestic turkey. The number of alleles per locus ranged from 5 to 15 and average heterozygosity was high for almost all loci. Domestic turkeys showed significantly reduced numbers of alleles per locus and overall heterozygosities when compared to eastern wild turkeys. The high variability in these markers should provide the level of resolution required to continue studies of wild turkey population genetics.