Search

This study was designed to assess effects of a diet containing endophyte (Acremonium coenophialum)-infected tall fescue seed on litter growth and development in mice. Twenty pairs of mature CD-1 mice were allocated to dietary treatments containing 50% (wt/wt) rodent chow plus either 50% endophyte-infected tall fescue seed or seed that was not infected. At parturition, six pups of approximately equal BW and sex ratio were selected from each litter and fostered to each of the dams for suckling, resulting in four suckling groups. Pups born to dams fed the infected diet weighed less at birth and experienced developmental delays in BW gain and in eye opening (16.7 vs. 13.7 d) regardless of the foster dam's diet. Pups born of dams fed the diet that was not infected attained the greatest growth rates and weaning weights; those suckling dams fed the diet that was not infected demonstrated the largest gains. Pups born of and suckled by dams fed the infected diet demonstrated greatly reduced growth rates and weaning weights compared with the other groups. Results suggest that the congenital effect on pups born of dams fed an infected diet was significant in lowering the growth rate of the pups during suckling. The dam's ability to provide nourishment to the pups also was lowered when fed this diet. When these two factors were combined, the differences were greater than for either factor separately.

A laboratory bioassay to distinguish isolates of Peronospora tabacina D.B. Adam was developed utilizing 7-mm acetone-dipped disks cut from tobacco leaf panels from several cultivars of Nicotiana tabacum, sporangiospores of P. tabacina, a germination indicator (Calcofluor), and fluorescence microscopy. Sporangiospore germination percentage of each isolate X cultivar pair was determined. Mean germination of sporangiospores differed between domestic and international collection locations (except between the two Mexican isolates). These results suggest the presence of different pathotypes of P. tabacina

A 232-bp DNA sequence was obtained from random amplified polymorphic DNA of Peronospora tabacina, the blue mold pathogen of tobacco. This sequence had homology to P. tabacina DNA but not to DNA of other downy mildew or oomycetous fungi tested. The fragment was determined to be part of a repetitive DNA sequence that was ubiquitous in a worldwide collection of P. tabacina. Oligonucleotides were designed for amplification of this sequence by polymerase chain reaction. The fragment was reliably amplified with amounts of DNA (1-10 fg) that are less than that contained in a single P. tabacina sporangiospore. Use of this technique enabled the detection of P. tabacina DNA directly in local lesions, systemic vascular infections, and other infected parts of tobacco plants [...]