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Winter Wheat Cultivars (winter + wheat_cultivar)
Selected AbstractsUltrastructural and Immunocytochemical Studies on Effects of Barley Yellow Dwarf Virus , Infection on Fusarium Head Blight, Caused by Fusarium graminearum, in Wheat PlantsJOURNAL OF PHYTOPATHOLOGY, Issue 1 2006Y. Liu Abstract The interactions between barley yellow dwarf virus (BYDV) and Fusarium head blight (FHB), caused by Fusarium graminearum, were studied in the two winter wheat cultivars (cvs.), Agent (susceptible to FHB) and Petrus (moderately resistant to FHB), using ultrastructural and immunocytochemical methods. Infections of wheat plants of both cvs. by BYDV increased susceptibility to FHB. BYDV infection caused numerous cytological changes in lemma tissue of both cvs. such as formation of vesicles in the cytoplasm, degradation of fine structures of chloroplasts of both cvs. and accumulation of large starch grains in the chloroplasts. Electron microscopical studies showed that the development of F. graminearum on spike surfaces was not affected in BYDV-infected plants. After penetration and intercellular growth in lemma tissue, defence responses to Fusarium infections were markedly reduced in BYDV-diseased plants compared to the tissue of virus-free plants. At sites of contact of fungal cells with host tissue, depositions of cell wall material were distinctly less pronounced than in tissues of virus-free plants of cv. Petrus. Detection of , -1,3-glucanases and chitinases in lemma tissue of cv. Agent revealed no appreciably increased accumulation of both defence enzymes in F. graminearum -infected virus-free and BYDV-infected tissues compared to the non-infected control tissue. On the other hand, in cv. Petrus, infection with F. graminearum induced a markedly enhanced activity of both enzymes 3 days after inoculation. The increase of both enzyme activities was less pronounced in BYDV-infected plants than in tissue exclusively infected with F. graminearum. Cytological studies suggest that in contrast to the susceptible cv. Agent postinfectional defence responses may play still an important role in the resistance of the moderately resistant cv. Petrus to FHB. [source] Studies on Symptom Development, Phenolic Compounds and Morphological Defence Responses in Wheat Cultivars Differing in Resistance to Fusarium Head BlightJOURNAL OF PHYTOPATHOLOGY, Issue 4-5 2002E. SIRANIDOU Abstracts Development of Fusarium head blight, caused by Fusarium culmorum, was evaluated in seven winter wheat cultivars and one spring wheat cultivar in an outdoor pot experiment. Of the cultivars studied, only the spring wheat cultivar Frontana exhibited resistance against initial infection by the fungus. Significantly higher amounts of free phenolic compounds were found in the glumes, lemmas and paleas of Frontana prior to and at all sampling times after inoculation, in comparison to the winter wheat cultivar Agent. Furthermore, the amount of p -coumaric acid increased significantly in the glumes, lemmas and paleas of the cultivar Frontana 2 days after inoculation compared to that in uninoculated spike tissues. However, the amounts of ferulic acid between inoculated and healthy plant tissues did not differ. Ultrastructural studies indicated more pronounced structural defence responses, such as cell wall appositions, in the infected lemma tissue of the resistant cultivar Frontana compared with the susceptible Agent 3 days after inoculation. Immunogold labelling of lignin revealed no differences in the density of gold particles on the cell walls of healthy lemma tissue in the two cultivars. However, density of particles increased in the infected lemma tissue of the resistant cultivar Frontana on cell walls adjacent to the fungal cells, 3 days after inoculation. The susceptible cultivar Agent showed little or no response to the infection. Phenolic compounds appear to play a role in the resistance of the cultivar Frontana to F. culmorum. [source] Evidence of a major genetic factor conditioning freezing sensitivity in winter wheatPLANT BREEDING, Issue 3 2008D. Z. Skinner Abstract The inheritance of freezing tolerance in F2 -derived F4 populations from all possible crosses of winter wheat cultivars ,Kestrel', ,Eltan', ,Tiber', ,Froid' and germplasm line Oregon Feed Wheat #5 (ORFW) was investigated. When frozen to a temperature equal to the LT50 of the least freezing tolerant parent (ORFW), survival frequency distributions were skewed to greater survival in six of the 10 crosses, however, very few of the progeny from the four crosses to ORFW survived. The inheritance of this freezing sensitivity was investigated with freezing of F2:4 populations from the crosses of ORFW to ,Eltan' or ,Tiber' to the LT50 of the hardier parent. Very few of the F2:4 populations survived as well as ,Eltan' or ,Tiber', indicating a small number of strongly dominant genetic factors in ORFW that conditioned freezing sensitivity. Molecular analysis indicated these factors were not spring-type vernalization alleles. [source] Inheritance of resistance to wheat midge, Sitodiplosis mosellana, in spring wheatPLANT BREEDING, Issue 5 2002R. I. H. McKenzie Abstract Inheritance of resistance to a wheat midge, Sitodiplosis mosellana (Géhin), was investigated in spring wheats derived from nine resistant winter wheat cultivars. F1 hybrids were obtained from crosses between resistant winter wheats and susceptible spring wheats, and used to generate doubled haploid populations. These populations segregated in a ratio of 1:1 resistant to susceptible, indicating that a single gene confers the resistance. The F2 progeny from an intercross among spring wheats derived from the nine resistance sources did not segregate for resistance. Therefore, the same gene confers resistance in all nine sources of resistance, although other genes probably affect expression because the level of resistance varied among lines. Heterozygous plants from five crosses between diverse susceptible and resistant spring wheat parents all showed intermediate levels of response, indicating that resistance is partly dominant. Susceptible plants were reliably discriminated from heterozygous or homozygous resistant ones in laboratory tests, based on the survival and development of wheat midge larvae on one or two spikes. This powerful resistance gene, designated Sm1, is simply inherited and can be incorporated readily into breeding programmes for spring or winter wheat. However, the use of this gene by itself may lead to the evolution of a virulent population, once a resistant cultivar is widely grown. [source] | ||||||||||