Doctor of Philosophy / The responses of 92 barley genotypes to selected P. hordei pathotypes was assessed in greenhouse tests at seedling growth stages and in the field at adult plant growth stages to determine known or unknown resistances. On the basis of multipathotype tests, 35 genotypes were postulated to carry Rph2, Rph4, Rph5, Rph12, RphCantala alone or combinations of Rph2 + Rph4 and Rph1 + Rph2, whereas 52 genotypes lacked detectable seedling resistance to P. hordei. Five genotypes carried seedling resistance that was effective to all pathotypes tested, of which four were believed to carry uncharacterised resistance based on pedigree information. Field tests at adult plant growth stages indicated that while 28 genotypes were susceptible, 57 carried uncharacterised APR to P. hordei. Pedigree analysis indicated that APR in the test genotypes could have been derived from three different sources. The resistant responses of seven cultivars at adult plant growth stages were believed to be due to the presence of seedling resistance effective against the field pathotypes. Genetic studies conducted on 10 barley genotypes suggested that ‘Vada’, ‘Nagrad’, ‘Gilbert’, ‘Ulandra (NT)’ and ‘WI3407’ each carry one gene providing adult plant resistance to P. hordei. Genotypes ‘Patty’, ‘Pompadour’ ‘Athos’, ‘Dash’ and ‘RAH1995’ showed digenic inheritance of APR at one field site and monogenic inheritance at a second. One of the genes identified in each of these cultivars provided high levels of APR and was effective at both field sites. The second APR gene was effective only at one field site, and it conferred low levels of APR. Tests of allelism between resistant genotypes confirmed a common APR gene in all genotypes with the exception of ‘WI3407’, which based on pedigree information was genetically distinct from the gene common in ‘Vada’, ‘Nagrad’, ‘Patty’, ‘RAH1995’ and ‘Pompadour’. An incompletely dominant gene, Rph14, identified previously in an accession of Hordeum vulgare confers resistance to all known pathotypes of P. hordei in Australia. The inheritance of Rph14 was confirmed using 146 and 106 F3 lines derived from the crosses ‘Baudin’/ ‘PI 584760’ (Rph14) and ‘Ricardo’/‘PI 584760’ (Rph14), respectively. Bulk segregant analysis on DNA from the parental genotypes and resistant and susceptible DNA bulks from F3 lines using diversity array technology (DArT) markers located Rph14 to the short arm of chromosome 2H. Polymerase chain reaction (PCR) based marker analysis identified a single simple sequence repeat (SSR) marker, Bmag692, linked closely to Rph14 at a map distance of 2.1 and 3.8 cM in the populations ‘Baudin’/ ‘PI 584760’and ‘Ricardo’/‘PI 584760’, respectively. Seedlings of 62 Australian and two exotic barley cultivars were assessed for resistance to a variant of Puccinia striiformis, referred to as BGYR, which causes stripe rust on several wild Hordeum species and some genotypes of cultivated barley. With the exception of six Australian barley cultivars and an exotic cultivar, all displayed resistance to the pathogen. Genetic analyses of six Australian barley cultivars and the Algerian barley ‘Sahara 3771’, suggested that they carried either one or two major seedling resistance genes to the pathogen. A single recessive seedling resistance gene, Bgyr1, identified in ‘Sahara 3771’ was located on the long arm of chromosome 7H and flanked by restriction fragment length polymorphism (RFLP) markers wg420 and cdo347 at genetic distances of 12.8 and 21.9 cM, respectively. Mapping resistance to BGYR at adult plant growth stages using a doubled haploid population derived from the cross ‘Clipper’/‘Sahara 3771’ identified two major QTLs on the long arms of chromosomes 3H and 7H that explained 26 and 18% of total phenotypic variation, respectively. The QTL located on chromosome 7HL corresponded to the seedling resistance gene Bgyr1. The second QTL was concluded to correspond to a single adult plant resistance gene designated Bgyr2, originating from cultivar ‘Clipper’.

Errata attached to inside front cover. Bibliography: leaves [156-188]

1 v. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, Waite Agricultural Research Institute, 1993

Includes bibliographical references (l5 leaves) / vi, 126, [49] leaves, [17] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of the work presented in this thesis was to develop molecular genetic markers for YD2 (the gene in barley which provides protection against barley yellow dwarf luteovirus) which could be used for the marker assisted selection of the gene in breeding programs and enable the gene to be cloned via a map-based approach. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1998

Bibliography: leaves 121-141.

Bibliography: leaves 118-132. This thesis examines the structure and gene expression of barley yellow dwarf viruses (BYDVs)-PAV in order to gain a better understanding of the interaction between the virus and the Yd2 resistance gene. The protein products of open reading frame (ORF)3, ORF4 and ORF5 are expressed in bacterial cells, in order to characterise the BYDV-PAV virion-associated proteins. The effect of the Yd2 resistance gene on the expression of the BYDV-PAV viral proteins in infected cells is also studied.

Bibliography: leaves 173-200 / iv, 200 leaves, 7 leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1986

Bibliography: leaves 121-141. / viii, 151 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1996?

Bibliography: leaves 118-132. / iv, 132 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis examines the structure and gene expression of barley yellow dwarf viruses (BYDVs)-PAV in order to gain a better understanding of the interaction between the virus and the Yd2 resistance gene. The protein products of open reading frame (ORF)3, ORF4 and ORF5 are expressed in bacterial cells, in order to characterise the BYDV-PAV virion-associated proteins. The effect of the Yd2 resistance gene on the expression of the BYDV-PAV viral proteins in infected cells is also studied. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1997

Doctor of Philosophy / The responses of 92 barley genotypes to selected P. hordei pathotypes was assessed in greenhouse tests at seedling growth stages and in the field at adult plant growth stages to determine known or unknown resistances. On the basis of multipathotype tests, 35 genotypes were postulated to carry Rph2, Rph4, Rph5, Rph12, RphCantala alone or combinations of Rph2 + Rph4 and Rph1 + Rph2, whereas 52 genotypes lacked detectable seedling resistance to P. hordei. Five genotypes carried seedling resistance that was effective to all pathotypes tested, of which four were believed to carry uncharacterised resistance based on pedigree information. Field tests at adult plant growth stages indicated that while 28 genotypes were susceptible, 57 carried uncharacterised APR to P. hordei. Pedigree analysis indicated that APR in the test genotypes could have been derived from three different sources. The resistant responses of seven cultivars at adult plant growth stages were believed to be due to the presence of seedling resistance effective against the field pathotypes. Genetic studies conducted on 10 barley genotypes suggested that ‘Vada’, ‘Nagrad’, ‘Gilbert’, ‘Ulandra (NT)’ and ‘WI3407’ each carry one gene providing adult plant resistance to P. hordei. Genotypes ‘Patty’, ‘Pompadour’ ‘Athos’, ‘Dash’ and ‘RAH1995’ showed digenic inheritance of APR at one field site and monogenic inheritance at a second. One of the genes identified in each of these cultivars provided high levels of APR and was effective at both field sites. The second APR gene was effective only at one field site, and it conferred low levels of APR. Tests of allelism between resistant genotypes confirmed a common APR gene in all genotypes with the exception of ‘WI3407’, which based on pedigree information was genetically distinct from the gene common in ‘Vada’, ‘Nagrad’, ‘Patty’, ‘RAH1995’ and ‘Pompadour’. An incompletely dominant gene, Rph14, identified previously in an accession of Hordeum vulgare confers resistance to all known pathotypes of P. hordei in Australia. The inheritance of Rph14 was confirmed using 146 and 106 F3 lines derived from the crosses ‘Baudin’/ ‘PI 584760’ (Rph14) and ‘Ricardo’/‘PI 584760’ (Rph14), respectively. Bulk segregant analysis on DNA from the parental genotypes and resistant and susceptible DNA bulks from F3 lines using diversity array technology (DArT) markers located Rph14 to the short arm of chromosome 2H. Polymerase chain reaction (PCR) based marker analysis identified a single simple sequence repeat (SSR) marker, Bmag692, linked closely to Rph14 at a map distance of 2.1 and 3.8 cM in the populations ‘Baudin’/ ‘PI 584760’and ‘Ricardo’/‘PI 584760’, respectively. Seedlings of 62 Australian and two exotic barley cultivars were assessed for resistance to a variant of Puccinia striiformis, referred to as BGYR, which causes stripe rust on several wild Hordeum species and some genotypes of cultivated barley. With the exception of six Australian barley cultivars and an exotic cultivar, all displayed resistance to the pathogen. Genetic analyses of six Australian barley cultivars and the Algerian barley ‘Sahara 3771’, suggested that they carried either one or two major seedling resistance genes to the pathogen. A single recessive seedling resistance gene, Bgyr1, identified in ‘Sahara 3771’ was located on the long arm of chromosome 7H and flanked by restriction fragment length polymorphism (RFLP) markers wg420 and cdo347 at genetic distances of 12.8 and 21.9 cM, respectively. Mapping resistance to BGYR at adult plant growth stages using a doubled haploid population derived from the cross ‘Clipper’/‘Sahara 3771’ identified two major QTLs on the long arms of chromosomes 3H and 7H that explained 26 and 18% of total phenotypic variation, respectively. The QTL located on chromosome 7HL corresponded to the seedling resistance gene Bgyr1. The second QTL was concluded to correspond to a single adult plant resistance gene designated Bgyr2, originating from cultivar ‘Clipper’.