Partial resistance to leaf rust in a collection of ancient Spanish barleys

A collection of 569 Spanish barley accessions was screened for resistance to leaf rust (Puccinia hordei Otth) in the field at Cordoba during the 2000-2001 season. The level of resistance ranged from very low to very high. In 14% of the accessions the relative AUDPC (L94 = 100%) was lower than 10%. Selected accessions that were most resistant in the field, were tested in the seedling stage under controlled conditions. Macroscopic components of resistance indicated that six lines had a high level of partial resistance close to check cv. Vada and one line a similar level of partial resistance. Histological studies indicated that the resistance was based on a high percentage of early aborted colonies and reduction in colony size without plant cell necrosis. Three of the selected lines showed high percentage of plant cell necrosis associated with established colonies, which indicates a combination of prehaustorial resistance with late acting incomplete posthaustorial resistance. Although the new barley varieties already incorporate some partial resistance, new sources of partial resistance like these are needed to improve durability of the resistance

Characterization of Lr46, a gene conferring partial resistance to wheat leaf rust

Components of resistance conferred by the Lr46 gene, reported as causing "slow rusting" resistance to leaf rust in wheat, were studied and compared with the effects of Lr34 and genes for quantitative resistance in cv. Akabozu. Lr34 is a gene that confers non-hypersensitive type of resistance. The effect of Lr46 resembles that of Lr34 and other wheats reported with partial resistance. At macroscopic level, Lr46 produced a longer latency period than observed on the susceptible recurrent parent Lalbahadur, and a reduction of the infection frequency not associated with hypersensitivity. Microscopically, Lr46 increased the percentage of early aborted infection units not associated with host cell necrosis and decreased the colony size. The effect of Lr46 is comparable to that of Lr34 in adult plant stage, but in seedling stage its effect is weaker than that of Lr34

The importance of human rights protection in the internal protection alternative inquiry

Since the 1980s, Western states have denied refugee status for asylum seekers who can receive protection in a part of their country of nationality other than that of their habitual residence based on the principle of the internal protection alternative (IPA). Since then, this principle has been applied very inconsistently. While some jurisdictions require a high level of human rights protection in the IPA area, others return asylum seekers to such an area despite a history of significant human rights violations. The question that this thesis aims to answer is: What is the required level of human rights protection in the IPA area under the 1951 Convention Relating to the Status of Refugees? This thesis explores the current approaches to assessing the required level of human rights protection. This thesis then argues for a new approach, which is more in line with the Refugee Convention. Using a contextual approach of the legal basis of the IPA inquiry, it is argued that the new approach must assess whether basic civil and political rights are respected in the IPA zone, as “national protection” under the Refugee Convention entails at least the protection of these rights. Furthermore, states must assess whether the conditions in the IPA zone may compel someone to return to the area of persecution, as returning someone an area with such conditions violates the prohibition of refoulement under Article 33(1) of the Refugee Convention. This thesis explores how a lack of respect for the rights to work, education and health may result in someone returning to the area of persecution. This is because in cases where people do not receive enough remuneration or unemployment assistance to sustain themselves and their families or cannot afford to access education or health services, they typically rely on support from their family and community. If they cannot access such support in the IPA area, but they believe they can in the area of persecution, they may therefore be compelled to return. Therefore, a high level of human rights protection is required in the IPA area

Pyramiding of Ryd2 and Ryd3 conferring tolerance to a German isolate of Barley yellow dwarf virus-PAV (BYDV-PAV-ASL-1) leads to quantitative resistance against this isolate

Barley yellow dwarf virus (BYDV) is an economically important pathogen of barley, which may become even more important due to global warming. In barley, several loci conferring tolerance to BYDV-PAV-ASL-1 are known, e.g. Ryd2, Ryd3 and a quantitative trait locus (QTL) on chromosome 2H. The aim of the present study was to get information whether the level of tolerance against this isolate of BYDV in barley can be improved by combining these loci. Therefore, a winter and a spring barley population of doubled haploid (DH) lines were genotyped by molecular markers for the presence of the susceptibility or the resistance encoding allele at respective loci (Ryd2, Ryd3, QTL on chromosome 2H) and were tested for their level of BYDV-tolerance after inoculation with viruliferous (BYDV-PAV-ASL-1) aphids in field trials. In DH-lines carrying the combination Ryd2 and Ryd3, a significant reduction of the virus titre was detected as compared to lines carrying only one of these genes. Furthermore, spring barley DH-lines with this allele combination also showed a significantly higher relative grain yield as compared to lines carrying only Ryd2 or Ryd3. The QTL on chromosome 2H had only a small effect on the level of tolerance in those lines carrying only Ryd2, or Ryd3 or a combination of both, but the effect in comparison to lines carrying no tolerance allele was significant. Overall, these results show that the combination of Ryd2 and Ryd3 leads to quantitative resistance against BYDV-PAV instead of tolerance

The phenotypic expression of QTLs for partial resistance to barley leaf rust during plant development

Partial resistance is generally considered to be a durable form of resistance. In barley, Rphq2, Rphq3 and Rphq4 have been identified as consistent quantitative trait loci (QTLs) for partial resistance to the barley leaf rust pathogen Puccinia hordei. These QTLs have been incorporated separately into the susceptible L94 and the partially resistant Vada barley genetic backgrounds to obtain two sets of near isogenic lines (NILs). Previous studies have shown that these QTLs are not effective at conferring disease resistance in all stages of plant development. In the present study, the two sets of QTL–NILs and the two recurrent parents, L94 and Vada, were evaluated for resistance to P. hordei isolate 1.2.1 simultaneously under greenhouse conditions from the first leaf to the flag leaf stage. Effect of the QTLs on resistance was measured by development rate of the pathogen, expressed as latency period (LP). The data show that Rphq2 prolongs LP at the seedling stage (the first and second leaf stages) but has almost no effect on disease resistance in adult plants. Rphq4 showed no effect on LP until the third leaf stage, whereas Rphq3 is consistently effective at prolonging LP from the first leaf to the flag leaf. The changes in the effectiveness of Rphq2 and Rphq4 happen at the barley tillering stage (the third to fourth leaf stages). These results indicate that multiple disease evaluations of a single plant by repeated inoculations of the fourth leaf to the flag leaf should be conducted to precisely estimate the effect of Rphq4. The present study confirms and describes in detail the plant development-dependent effectiveness of partial resistance genes and, consequently, will enable a more precise evaluation of partial resistance regulation during barley developmen

Search for partial resistance to leaf rust in a collection of ancient Spanish wheats

A collection of 917 accessions of Spanish durum and bread wheat was screened for resistance to leaf rust (Puccinia triticina) under field conditions at three locations. Resistance levels ranged from very low to very high, high susceptibility being most frequent. Relative disease severity (referred to the most susceptible accession = 100 %) was lower than 20 % in about 6 % of the accessions in each location. In the collection most of the lines (84 %)displayed a susceptible infection type. A final selection of seven accessions (one of them durum) displaying low severity level in the field and high infection type in a growth chamber was chosen for further studies. High levels of partial resistant with longer latency period and high percentage of early aborted colonies without necrosis were found. They might be used in breeding programmes

^1H{^(19)F} NOE NMR Structural Signatures of the Insulin R_6 Hexamer: Evidence of a Capped HisB10 Site in Aryl- and Arylacryloyl-carboxylate Complexes

New and improved insulin: ^1H{^(19)F} NOE NMR difference spectra for CF_3-substituted aromatic carboxylates bound at the HisB10 sites of the R_6 human insulin (HI) hexamer show strong NOEs between the CF_3 groups and the LeuB6, AsnB3, and PheB1 sidechains. The NOEs and structural modeling establish that these carboxylates form closed complexes with the HisB10 site capped by the PheB1 rings