Showing papers on "Rust published in 1992"

Genetic association of leaf rust resistance gene Lr34 with adult plant resistance to stripe rust in bread wheat

Abstract: Near-isogenic Thatcher lines (viz., RL6058, RL6077, and Line 920) carrying gene Lr34 for leaf rust resistance, Frontana, and various other wheat cultivars carrying Lr34 displayed adult plant resistance to stripe rust in Mexico. F2 populations or F3 lines from several intercrosses of wheats carrying Lr34 did not segregate for susceptibility to stripe rust and leaf rust, indicating that at least one resistance gene was common in each parent. An evaluation of F3 lines for stripe rust and leaf rust, from the crosses of stripe rust and leaf rust susceptible Jupateco 73S with stripe rust and leaf rust resistant Condor and Jupateco 73R, showed linked segregation for the two diseases. For each disease, resistance was conferred by one partially dominant gene. Because Lr34 is located on chromosome 7D, the linked Yr gene is designated Yr18. RL6058, RL6077, Line 920, Condor, or Jupateco 73R could be used as tester genotypes for Yr18. The durable adult plant stripe rust resistance of Anza, a related sib of the parent of Condor, is postulated to be attributable to Yr18, which is widespread in cultivars from the International Maize and Wheat Improvement Center germ plasm and South American wheats. An additional adult plant stripe rust resistance gene was present in both Sonoita 81 and Tonichi 81

Effect of gene Lr34 in the enhancement of resistance to leaf rust of wheat

Abstract: Leaf rust resistance gene Lr34 is present in many wheat cultivars throughout the world that have shown durable resistance to leaf rust. Fourteen pair-wise combinations of Lr34 and seedling leaf rust resistance genes were developed by intercrossing near isogenic 'Thatcher' lines. In both seedling and adult plant tests homozygous paired combinations of specific resistance genes with Lr34 had enhanced resistance relative to either parent to different numbers of isolates that were avirulent to the additional resistance genes. The TcLr34, 18 line also expressed enhanced resistance to specific isolates virulent to Lr18 in seedling and adult plant stages. In rust nursery tests, homozygous lines were more resistant than either parent, if the additional leaf rust gene conditioned an effective of resistance when present singly. The ability of Lr34 to interact with other genes conditioning effective resistance may contribute to the durability of leaf rust resistance in cultivars with Lr34.

Inheritance of Slow-Rusting Resistance to Leaf Rust in Wheat

Abstract: Race-specific resistance of wheat (L. emend. Thell.) to leaf rust (f. sp.) is often short-lived. Slow-rusting resistance has been reported to be a more durable type of resistance. To exploit the advantages of this durability, genetic analysis of slow rusting is essential. Inheritance of slow-rusting resistance to leaf rust was studied in F families of spring wheat in two field experiments. The F families resulted from two diallel crosses involving one fast-rusting and either five or two slow-rusting wheat genotypes. Parents and progenies were evaluated in replicated field trials under epidemics initiated by artificial inoculation. The area under disease progress curve (AUDPC) was used to measure rust severity over time. Significant differences in AUDPC were observed among crosses and among progeny within crosses. Mean AUDPC values of crosses ranged from 16 to 538. Predominantly additive genetic variance for slow rusting was detected, but additive × additive genetic variance also was present. Narrow-sense heritability varied from 45 to 92%, depending on the cross. Correlation coefficients between slow rusting and plant maturity were negative and low. Positive but low correlation coefficients between plant height and slow rusting were observed. Results indicated that early-generation selection for slow-rusting resistance to leaf rust in wheat should be effective, and would not be significantly influenced by either plant height or plant maturity.

Analysis of durable resistance to stem rust in barley

Abstract: Since the mid-1940’s, barley cultivars grown in the northern Great Plains of the USA and Canada have been resistant to stem rust caused by Puccinia graminis f. sp. tritici. This durable resistance is largely conferred by a single gene, Rpg1, derived from a single plant selection of the cultivar Wisconsin 37 and an unimproved Swiss cultivar. At the seedling stage, barley genotypes with Rpg1 generally exhibit low mesothetic reactions at 16–20° C and slightly higher mesothetic reactions at 24–28°C to many stem rust pathotypes. This resistance is manifested by a low level of rust infection and mostly incompatible type uredia on adult plants. Rpg1 reacts in a pathotype-specific manner since some genotypes of P. g. f. sp. tritici are virulent on cultivars carrying this gene in the field. Several factors may have contributed to the longevity of stem rust resistance in barley, a) since barley is planted early and matures early, it can sometimes escape damage from stem rust inoculum carried from the south; b) one or more minor genes may augment the level of resistance already provided by Rpg1; c) the cultivation of resistant wheat cultivars and eradication of barberry have reduced the effective population size and number of potential new pathotypes of P. g. f. sp. tritici, respectively; and d) virulent pathotypes of P. g. f. sp. tritici and P. g. f. sp. secalis have not become established. This situation changed in 1989 when a virulent pathotype (Pgt-QCC) of P. g. f. sp. tritici became widely distributed over the Great Plains. However, Rpg1 may still confer some degree of resistance to pathotype QCC because stem rust severities have been low to moderate and yield losses light on barley cultivars carrying the gene during the last four seasons (1989–1992). Several sources of incomplete resistance to pathotype QCC have been identified in barley. To facilitate the transfer of resistance genes from these sources into advanced breeding lines, molecular marker assisted selection is being employed.

Increased photosynthesis and resistance to rust infection in upper, uninfected leaves of rusted broad bean (Vicia faba L.)

Abstract: SUMMARY Photosynthesis and resistance to rust infection were studied in upper, uninfected leaves of broad bean, Vicia faba L., where the lower two leaves were infected with rust, Uromyces viciae-fabae (Pers.) Shroet. Following inoculation of the lower leaves, rates of net photosynthesis were significantly increased in the upper, uninfected, fully-developed leaves and the young developing leaves, compared to controls. In contrast, photosynthesis was substantially reduced in the lower, rusted leaves. When 14CO2 was fed to the upper, uninfected leaves of rusted plants, there was a considerable increase in labelled assimilate in those leaves, compared to controls. In addition, there was substantial movement of labelled assimilate into lower, rusted leaves, into young, developing leaves and into roots. On the other hand, there was a substantial reduction in labelled assimilates moving into shoot apices. Upper, uninfected leaves of rusted beans exhibited Increased resistance to rust infection. Thus, the percentage leaf area covered with rust and the number of pustules per cm2 were reduced in these leaves compared to controls. This resistance to rust infection was greatest when the upper leaves were challenged 1 d after inoculation of the lower leaves with rust and decreased with increasing time after inoculation of the lower leaves. Young, developing leaves on rusted beans also exhibited increased resistance to rust infection. When photosynthesis in the upper leaves was reduced to near control values or well below control values by shading, resistance to rust infection in those leaves was also reduced, although not in proportion to the reduction in photosynthesis. It is suggested that the increased photosynthesis in upper, uninfected bean leaves probably facilitates maximum expression of resistance to infection in those leaves.

Suppression of rust resistance in bread wheat (Triticum aestivum L.) by D-genome chromosomes

Abstract: Several tests were done in bread wheat (Triticum aestivum L.) to demonstrate the occurrence of genes on D-genome chromosomes that suppress resistance to leaf rust (Puccinia recondita f. sp. tritici Rob. ex Desm.) and stem rust (Puccinia graminis f. sp. tritici Eriks. &Henn.). Ten rust-resistant wild tetraploid wheats (T. turgidum var. dicoccoides) were crossed with both durum (T. turgidum var. durum) and bread wheats. In all cases, resistance to leaf rust and stem rust was expressed in the hybrids with durum wheats but suppressed in the hybrids with bread wheats. Crosses were made between five diverse durum wheats and four diverse bread wheats. The pentaploid hybrid seedlings of 12 crosses were tested with leaf rust race 15 and in all cases the resistance of the durum parents was suppressed. Fourteen D-genome disomic chromosome substitution lines in the durum wheat 'Langdon' were tested with stem rust race 15B-1 and leaf rust race 15. Chromosomes 1B, 2B, and 7B were found to carry genes for resistance to ...

Characterization of rust-resistant wheat-Agropyron intermedium derivatives by C-banding, in situ hybridization and isozyme analysis.

Abstract: Chromosome constitutions of three wheat-Agropyron intermedium derivatives were identified by C-banding analysis, in situ hybridization using biotin-labeled genomic Ag. intermedium DNA as a probe and isozyme analysis. Lines W44 and W52 were identified as 7Ai-2(7D) and 7Ai-2(7A) chromosome substitution lines carrying the same chromosome pair of Ag. intermedium. The alien chromosome was found to be homoeologous to group 7 based on C-banding, meiotic pairing and isozyme analyses. Line W49 was identified as a wheat Ag. intermedium chromosome translocation line. The breakpoint of the T2AS · 2AL-7Ai-2L translocation is located in the long arm at a fraction length of 0.62, and the transferred Ag. intermedium segment has a size of about 2.4 μm. Lines W44 and W52 expressed Ag. intermedium genes for resistance to leaf rust, stripe rust and stem rust, but only leaf rust resistance was expressed in W49. The results show that the leaf rust resistance gene(s), designated Lr38, is located in the distal half of the long arm of chromosome 7Ai-2, whereas the genes for resistance to stem rust and stripe rust are located either in the short arm or in the proximal region of the long arm of this chromosome.

Induction of systemic resistance to rust in Vicia faba by phosphate and EDTA: effects of calcium

Abstract: Resistance in the upper leaves of broad bean (Vicia faba) plants to infection by the rust fungus, Uromyces viciae-fabae, was increased following treatment of the lower leaves with 10 mm potassium phosphate or 5 mm EDTA. Increasing the interval between treatment of the lower leaves and inoculation of the upper leaves had little effect on rust infection. Thus rust infection was reduced by 50 and 34% if the upper leaves were inoculated 1 day after treatment of the lower leaves with potassium phosphate or EDTA, respectively, while there was a 75% reduction in infection if the interval between treatment and inoculation was increased to 12 days. Application of calcium nitrate (10 mm) after the phosphate or EDTA treatments prevented the induction of systemic resistance. Calcium nitrate applied alone to the lower leaves had no significant effect on rust infection of the upper leaves.

Enhanced leaf rust resistance in wheat conditioned by resistance gene pairs with Lr13

Abstract: Leaf rust resistance gene Lr13 is present in many North American hard red spring wheat cultivars that have shown durable resistance to leaf rust. Fifteen pair-wise combinations of Lr13 and seedling leaf rust resistance genes were developed by intercrossing near isogenic Thatcher lines. In both seedling and adult plant tests, homozygous paired combinations of specific resistance genes with Lr13 had enhanced resistance relative to either parent to rust isolates that had intermediate avirulent infection types to the additional genes. In field tests, homozygous lines were more resistant than either parent if the additional leaf rust gene conditioned an effective level of resistance when present singly.

Mechanisms of alteration in bean rust epidemiology due to intercropping with maize

Abstract: We performed experiments to identify how maize influences bean rust (caused by Uromyces appendiculatus) in maize-bean intercrops. The effects of competition with maize and interference by maize on dispersal of rust urediniospores were evaluated in trials conducted three times during 1989 and 1990. Alterations in the nondispersal (infection) phase of the pathogen life cycle due to intercropping and competition with maize also were assessed. Overall effects of maize on rust severity were evaluated in another experiment (...)

A region of heterogeneity adjacent to the 5s ribosomal RNA gene of cereal rusts

Abstract: Total genomic DNA was isolated from three cereal stem rusts, Puccinia graminis f. sp. tritici, f. sp. secalis, f. sp. avenae, and two cereal leaf rusts, P. recondita f. sp. tritici and P. coronata f. sp. avenae, and analyzed for the presence of heterogeneity in the intergenic region of the ribosomal DNA repeat unit. A 1 kb region of the repeat unit between the 26s and the 5s rRNA genes (IGR-1) was amplified by PCR and was found to be heterogeneous within each isolate and variable in size between races and species. The PCR results were confirmed by Southern blot analysis of native DNA. In an isolate of race C36(48), heterogeneity appeared to be due to variable numbers of 0.1 kb subrepeats in IGR-1. Nine wheat stem rust strains representing nine different races produced a unique pattern of heterogeneity while two different isolates of one race were identical, as were five of another. This may provide a rapid method for race identification in wheat stem rust. Heterogeneity and polymorphism in rye stem rust, oat stem rust, wheat leaf rust, and oat crown rust, was less pronounced than in wheat stem rust. In the course of this work, the 5s rRNA gene was located and its position and orientation within the ribosomal repeat unit was established.

Resistance in spelt wheat to yellow rust: I. Formal analysis and variation for gliadin patterns

Abstract: Seven spelt wheat accessions of different origin were hybridized with the susceptible bread wheat cultivar Taichung 29 in order to study the genetics of their resistance to yellow rust (Puccinia striiformis Westend . f . sp . tritici) . One Iranian and five European accessions were found to carry Yr5 of Triticum aestivum ssp . spelta var . album, whereas a factor for resistance in the Iranian accession 415 was confirmed to be genetically distinct from Yr5. The alleles for resistance in each of the accessions studied showed a monogenic dominant mode of inheritance . Twenty-eight spelt wheat accessions, including those studied for their resistance to yellow rust, were subjected to polyacrylamide-gel-electrophoresis to study variation for gliadin storage protein patterns . Thirteen distinct patterns were revealed, implying the presence of duplicates within the studied spelt wheat collection .

Surveys of cereal diseases and pests in the Netherlands. 4. Occurrence of powdery mildew and rusts in winter wheat

Abstract: Results of annual surveys of winter wheat fields from 1974 to 1986 were compiled to describe epidemics of powdery mildew and rusts in relation to weather and cultivar resistance. An average of 29 and 70% of fields were infected by powdery mildew in May and July, respectively. Mildew prevalence in May was positively correlated with average temperature in October and with average temperature over the months December, January, February and March. In addition, it was correlated negatively with the average grade of mildew resistance of the cultivars sown each year. Prevalence of mildew in July did not show consistent correlations with weather characteristics nor with mildew prevalence in May. Yellow rust was usually not detected in May and on average 18% of the fields was infected in July. The occurrence of yellow rust decreased after 1977, when the farmers adopted cultivars resistant or moderately resistant to yellow rust. Brown rust was usually not detected in May, while in July on average 48% of the fields was infected. Brown rust intensity in July was high in years with a high March temperature and high precipitation during April and May. Black rust was rare in the Netherlands, with 3 and 1% of the fields infected in July 1977 and 1981, respectively.

Diseases and pests in energy crop plantations

Abstract: The Pest and Disease Management Activity was established in response to an awareness of the potential importance of pests and diseases in woody biomass production systems. Annual surveys in Canada, Eire, England, N. Ireland, Scotland and Sweden from 1987–1991 confirmed that rust disease ( Melampsora spp.) is currently the most serious problem in willow biomass production in Europe. Other pests and diseases cause problems only on a local scale, though they could become more generally severe. Increasing clonal susceptibility to rust and an an increasing association of premature defoliation with lower rust severity levels have occurred over the period. A high degree of intrinsic variability in pathogen populations is expressed as four formae speciales (f.spp.) and at least eight pathotypes of the most common rust species, M. epitea . The same f.spp. appear to occur among pathotypes in Sweden, New Zealand and the UK. A network of field experiments has been established, in collaboration with the Joint Trials Activity, to enable the rust pathotype composition to be compared between five countries. It also aims to identify an international set of standard willow clones to be utilized for characterizing rust pathotypes globally.

Host species specificity of the goldenrod rust fungus and the existence of rust resistance within some goldenrod species

Abstract: Five out of six species of goldenrod at a study site in Ontario had rust pustules in the field and also developed pustules after laboratory inoculation with urediospores of a single-pustule isolate...

High-temperature, adult-plant resistance to wheat stripe rust and effects on yield components

Abstract: High-temperature, adult-plant (HTAP) resistance to stripe rust (Puccinia striiformis West) in wheat (Triticum aestivum L. em Thell) has remained durable for at least 30 yr in the USA. The expression of HTAP resistance to stripe rust in six crosses of winter wheat was evaluated using F 6 populations at Pullman, WA in 1986 and F 7 populations at three environmentally different locations (Pullman, Mt. Vernon, and Walla Walla, WA) in 1987. Resistant families could not be differentiated at Pullman in 1986 and Walla Walla in 1987 because unfavorable weather delayed the development of rust (...)

Evidence for the existence of a single race of common rust caused by Puccinia melanocephala, in Australian sugar cane cultivars

Abstract: A detached-leaf method for testing for physiological races of common rust disease, caused by Puccinia melanocephala, in Australian sugar cane cultivars is described. Single-uredium isolates collected from various locations in Queensland, Australia, between 1978 and 1986 were screened. Host reaction type was specific to individual cultivars and did not vary when these cultivars were inoculated with different rust isolates. For each cultivar there was no difference in generation time for each isolate. These results suggest that there is only one physiological race present in the pathogen population in Queensland. Reported changes in the severity of common rust disease in sugarcane cultivars were caused by changes in environmental conditions rather than the development of new races of the pathogen. Rust infection fluctuated during the growth of sugar cane, with a major peak occurring at tillering and stem elongation, following moderate rainfall and temperatures between 12 and 25¦C. Rust was more severe on older leaves than on younger leaves.

Terpene cleaning compositions and methods of using the same

Abstract: This invention relates to the cleaning composition comprising a mixture of (A) at least about 10% by weight of a terpene, (B) from about 1% to about 20% by weight of a polyalkoxylated alcohol, an alkyl or alkenyl succinate, or mixtures thereof, and (C) water, wherein the mixture has an acidic pH and methods of using the same. These compositions have improved grease cutting and rust inhibiting abilities.

The role of Lr34 in imparting durable resistance to wheat leaf rust through gene interaction

Abstract: The leaf rust responses of wheat lines carrying the complementary genes Lr27 and Lr31 and the same genes in a Chinese Spring background which contains Lr34, indicate that Lr34 interacts with the complementary genes to give enhanced levels of field resistance to leaf rust. Lr34, particularly in combination with other genes, is considered to be an important gene for imparting a high degree of durable resistance to leaf rust. Its similarity to Sr2, an adult plant gene for resistance to stem rust and its association with adult plant resistances to stem and stripe rusts are discussed.

Genetic Diversity for Adult Plant Resistance to Leaf Rust (Puccinia recondita) in Near‐Isogenic Lines and in Indian Wheats

Abstract: Variation for adult plant resistance in near-isogenic wheat lines carrying Lrl4b, Lrl4ab and Lr30 in a ‘Thatcher’ background indicated the possible presence of novel adult plant resistance genes effective against the Indian leaf rust population. Sixty-one wheats released for cultivation in India were grown in isolated nurseries. Each nursery was separately inoculated with one of four leaf rust pathotypes which had been selected to aid identification of resistance effective only in the adult plant stage. Seven distinct response groups were recognised and a minimum of six sources of adult plant resistance were postulated. In a group of 14 wheats, resistance was explained on the basis of the seedling response genes that were identified. Similar results for two years with pathotype 77-1 gave support to the reliability of field tests. Adult plant resistance (APR) sources were either race-specific or effective against all pathotypes used. Seedlings of cultivars with APR showed susceptible reactions. The possible presence of Lr34 in Indian wheats and its role in durable leaf rust resistance are discussed.

Evaluation of Resistance to Stem Rust in Perennial Ryegrass Grown in Controlled and Field Conditions

Abstract: Six cultivars of perennial ryegrass were evaluated for reaction to Puccinia graminis subsp. graminicola in controlled conditions when plants were 8 or 14 wk old and in the field as mature plants. Plants in controlled conditions were rated for rust infection type (0-4 scale) after inoculation with urediniospores, and an average stem rust infection index (ASRII) was used to compare cultivars. Plants in the field were assessed for percent incidence of infection and severity (percent modified Cobb scale). The area under the disease progress curve (AUDPC) was used to compare cultivars (.)

Rust removing agent for stainless steel surface

Abstract: A rust removing agent for a stainless steel surface of an aqueous solution of phosphoric acid, a polyhydroxymonocarboxylic acid or a salt thereof and a surfactant.