Barley Yellow Dwarf of Winter Wheat: Effects on Germplasm, and Inheritance, Combining Ability, and Reciprocal Effect for Tolerance to the Barley Yellow Dwarf Virus

108 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.Investigation of the effects of the barley yellow dwarf virus (BYDV) on winter wheat germplasm showed fall infection to be more devastating than spring infection, reducing grain yield an average of 61% vs. 38% for spring infection. BYDV also decreased winter survival, plant height, number of heads, and kernel weight. Among 1700 winter wheat entries screened, none were found to possess outstanding tolerance, though genetic variability for tolerance to the virus exists and seems to be quantitatively inherited. Heritability of tolerance is low under both fall and spring infection, but is higher under fall than spring inoculation. An interaction of entries with time of inoculation (fall vs. spring) suggests entries show differential tolerance to fall and spring times of infection. In a 12-parent diallel mating design which included reciprocal crosses in both F(,1) and F(,2) generations, reciprocal effect accounted for very little of the variability among entries for tolerance to BYDV. General combining ability and specific combining ability mean squares were highly significant, with general combining ability accounting for more of the entry sums of squares. Parental tolerance to BYDV is a good indicator of worth as a parent, especially if the parent is very tolerant or very susceptible. General combining ability for grain yield is not related to general combining ability for tolerance to BYDV when yield of infected as percent of the control treatment is the measure of tolerance. Therefore, breeding for high yield will not lead to less yield loss under BYDV infection. There is a general agreement between combining ability effects in fall and spring inoculated treatments, leading to the conclusion that one should be able to test and develop tolerant varieties under one environment which are tolerant in the other environment.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Characterization of Ethiopian Wheat Germplasm for Resistance to Four Puccinia graminis f. sp. tritici Races Facilitated by Single-Race Nurseries

In Ethiopia, breeding rust resistant wheat cultivars is a priority for wheat production. A stem rust epidemic during 2013 to 2014 on previously resistant cultivar Digalu highlighted the need to determine the effectiveness of wheat lines to multiple races of Puccinia graminis f. sp. tritici in Ethiopia. During 2014 and 2015, we evaluated a total of 97 bread wheat and 14 durum wheat genotypes against four P. graminis f. sp. tritici races at the seedling stage and in single-race field nurseries. Resistance genes were postulated using molecular marker assays. Bread wheat lines were resistant to race JRCQC, the race most virulent to durum wheat. Lines with stem rust resistance gene Sr24 possessed the most effective resistance to the four races. Only three lines with adult plant resistance possessed resistance effective to the four races comparable with cultivars with Sr24. Although responses of the wheat lines across races were positively correlated, wheat lines were identified that possessed adult plant resistance to race TTKSK but were relatively susceptible to race TKTTF. This study demonstrated the importance of testing wheat lines for response to multiple races of the stem rust pathogen to determine if lines possessed non-race-specific resistance

Targeting Staphylococcus aureus quorum sensing with non-peptidic small molecule inhibitors

A series of 3-oxo-C12-HSL, tetramic acid and tetronic acid analogues was synthesized to gain insights into the structural requirements for quorum sensing inhibition in Staphylococcus aureus. Compounds active against agr were non-competitive inhibitors of the auto-inducing peptide (AIP)-activated AgrC receptor, by altering the activation efficacy of the cognate AIP-1. They appeared to act as negative allosteric modulators and are exemplified by 3-tetradecanoyltetronic acid 17 which reduced nasal cell colonization and arthritis in a murine infection model