The development of wheat (Triticum aestivum L.) cultivars that are resistant to Wheat streak mosaic virus (WSMV), yet competitive in yield under nondiseased conditions, is an objective for breeding programs in the Great Plains. This field study was conducted to compare classical and transgenic sources of resistance to WSMV. Three sets of germplasm were evaluated. These included adapted cultivar...

Studies of experimental infection of the cotton rat, Sigmodon hispidus, with the virulent Sheila Smith (R type) and the avirulent Si 7 (U type) strains of Rickettsia rickettsii were undertaken to evaluate the role of this native wild mammal in the ecology of Rocky Mountain spotted fever. The Sheila Smith strain, which was highly lethal for guinea pigs, was nonpathogenic for cotton rats. Serial ...

Effects of plant age on resource acquisition and stress tolerance processes is a largely unstudied subject in herbaceous perennials. In a field experiment, we compared rates of photosynthesis (A), ribulose-1,5-bisphosphate (RuBP) carboxylation capacity (V Cmax), maximum electron transport rate (J max), and triose phosphate utilization (TPU), as well as concentrations of Rubisco and sucrose-phos...

The effects of environmental conditions on population trends of plant-parasitic nematodes were studied in experimental plots of five wheatgrasses in the western Utah desert. In a 3-year (1984-86) field study, soil water and temperature affected the population trends of the ectoparasites, Tylenchorhynchus acutoides and Xiphinema americanum, and the migratory endoparasite, Pratylenchus neglectus,...

We evaluate the use of mitochondrial DNA (mtDNA) genetic markers to describe population structure and matrilineal kinship on a microgeographic scale. An analysis of restriction site variation in 134 cotton rats (Sigmodon hispidus) collected from a 3.2 hectare field revealed significant spatial and temporal heterogeneity in frequencies of mtDNA genotypes among nest sites. Inspection of particula...

A putative translocation line (#32), together with a disomic addition line (TAI27) and an octo-amphiploid line (Zhong3) of common wheat and Thinopyrum intermedium were characterized by restriction fragment length polymorphism (RFLP) analysis, using probes covering all seven homoeologous groups of Triticeae. Line 32 was confirmed to be a cryptic translocation line, based on the detection of mult...

soil affected by salt (nacl) is a major problem worldwide and in areas with potential agriculture; lands in many countries are not enough to support crop production. the development of salt tolerant cultivars would be enhanced by better understanding of the genetic control of tolerance to salt stress. a new cereal, tritipyrum, a range of amphiploids between triticum spp. and thinopyrum spp....

For the first time, using chromosome engineering of durum wheat, the underlying genetic determinants of a yield-improving segment from Thinopyrum ponticum (7AgL) were dissected. Three durum wheat-Th. ponticum near-isogenic recombinant lines (NIRLs), with distal portions of their 7AL arm (fractional lengths 0.77, 0.72, and 0.60) replaced by alien chromatin, were field-tested for two seasons unde...