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Leaf Rust (leaf + rust)

Distribution by Scientific Domains

Life Sciences	93%

Terms modified by Leaf Rust

leaf rust resistance

Selected Abstracts

Leaf rust and stripe rust resistance genes Lr54 and Yr37 transferred to wheat from Aegilops kotschyi

PLANT BREEDING, Issue 6 2005
G. F. Marais
Abstract The tendency of unpaired meiotic chromosomes to undergo centric misdivision was exploited to translocate leaf rust and stripe rust resistance genes from an Aegilops kotschyi addition chromosome to a group 2 chromosome of wheat. Monosomic and telosomic analyses showed that the translocation occurred to wheat chromosome arm 2DL. The introgressed region did not pair with the corresponding wheat 2DL telosome during meiosis suggesting that a whole arm may have been transferred. Female transmission of the resistance was about 55% whereas male transmission was strongly preferential (96%). The symbols Lr54 and Yr37 are proposed to designate the new resistance genes. [source]

Quantitative-genetic analysis of leaf-rust resistance in seedling and adult-plant stages of inbred lines and their testcrosses in winter rye

PLANT BREEDING, Issue 6 2002
T. Miedaner
Abstract Leaf rust is the most frequent leaf disease of winter rye in Germany. All widely grown population and hybrid varieties are susceptible. This study was undertaken to estimate quantitative-genetic parameters of leaf-rust resistance in self-fertile breeding materials with introgressed foreign leaf-rust resistances and to analyze the relative importance of seedling and adult-plant resistance. Forty-four inbred lines and their corresponding testcrosses with a highly susceptible tester line were grown in a field in four different environments (location-year combinations) with artificial inoculation. Plots were separated by a nonhost to promote autoinfections and minimize interplot interference. Leaf-rust severity was rated on three leaf insertions at three dates. The testcrosses showed a considerably higher disease severity than the lines. High correlations (r , 0.9, P = 0.01) existed among the leaf insertions and the rating dates. Large genotypic variation for resistance was found in both the inbred and testcross populations. Genotype-environment interaction and error variances were of minor importance, thus high entry-mean heritabilities were achieved. A tight correlation between the inbreds and their corresponding testcrosses was found (r = 0.88, P = 0.01). Heterosis for resistance was significant (P = 0.05), but not very important. In a seedling test with 20,30 single-pustule isolates, 34 out of 44 inbreds reacted race-specifically. From the remaining inbred lines, three were medium and seven highly susceptible. In a further greenhouse test with 16 inbreds, seven were susceptible and five were resistant in both seedling and adult-plant stages. The remaining four lines had adult-plant resistance. In conclusion, race-specific leaf-rust resistance can be selected among inbred lines per se. Lines should also be tested in the adult-plant stage. [source]

Molecular mapping of the leaf rust resistance gene Rph7 in barley

PLANT BREEDING, Issue 5 2000
A. Graner
Abstract Leaf rust of barley, caused by Puccinia hordei Otth, is an important foliar disease in most temperate regions of the world. Sixteen major leaf rust resistance (Rph) genes have been described from barley, but only a few have been mapped. The leaf rust resistance gene Rph7 was first described from the cultivar ,Cebada Capa' and has proven effective in Europe. Previously mapped restriction fragment length polymorphism (RFLP) markers have been used to determine the precise location of this gene in the barley genome. From the genetic analysis of a ,Bow-man'/,Cebada Capa' cross, Rph7 was mapped to the end of chromosome 3HS, 1.3 recombination units distal to the RFLP marker cMWG691. A codominant cleaved amplified polymorphic site (CAPS) marker was developed by exploiting allele-specific sequence information of the cMWG691 site and adjacent fragments of genomic DNA. Based on the large amount of polymorphism present in this region, the CAPS marker may be useful for the marker-assisted selection of Rph7 in most diverse genetic backgrounds. [source]

Rust severity in bioenergy willow plantations treated with additional nutrients

FOREST PATHOLOGY, Issue 1 2009
M. Toome
Summary A 3-year field study was carried out to determine the effect of wastewater irrigation and previous differences in mineral fertilization on the occurrence of willow leaf rust (Melampsora epitea). The experiment was conducted in two energy forest plantations: one designed for wastewater purification and the other as a mineral fertilization experiment. The severity of leaf rust on different clones and sites with different treatments was assessed by counting the number of uredinia per leaf unit area. Generally, plants irrigated with wastewater consistently had more leaf rust, irrespective of the study years or willow clones. Previous mineral fertilization had mixed effects on different clones 2 years after the last application. Three years after the last fertilizer application, however, no impact of the treatment on rust disease development was detected. In general, the rust levels differed from year to year probably due to climate. In this study, no correlation was detected between shoot age and rust severity, whereas climate and treatments strongly influenced leaf rust levels on some willow clones. [source]

Virulence Frequences of Puccinia triticina in Germany and the European Regions of the Russian Federation

JOURNAL OF PHYTOPATHOLOGY, Issue 1 2007
V. Lind
Abstract From 2001 to 2003, leaf rust was collected in different regions of Germany and the Russian Federation to generate single spore isolates and to study the structure of the pathogen populations by analyses of virulence. The virulence of isolates was tested with 38 near-isogenic lines each carrying a different resistance gene. The analyses of variance revealed significant effects for the frequency of virulent isolates, the regions and most interactions with years and regions, but no significance was found for the effects of years. In Germany, an increase of virulence frequencies was detected for Lr1 and Lr2a while a decrease was found for Lr3a, Lr3bg and Lr3ka. Such clear trends did not occur in Russia which may be due to the great agroclimatic differences between regions. The variance of the frequency of virulent isolates was used to estimate adequate sample sizes for the analysis of regional populations of leaf rust. This procedure resulted in more reliable information about the dynamic processes within the pathogen populations. In 2002 and 2003, all pathotypes in Germany had a combined virulence to Lr1, Lr2a, Lr2b, Lr15, Lr17 and Lr20 supplemented by a few other genes. The complexity of virulence was lower in the most frequent pathotypes. In Russia virulence to the alleles at locus Lr3 was very common. Using detached leaf segments in Germany and Russia it turned out that the most virulent pathotypes carry 34 and 32 virulence genes, respectively. Virulence to Lr9, Lr19, Lr24 and Lr38 was rare or even absent. The use of major genes, not overcome by corresponding virulent pathotypes, may contribute to more durable types of resistance in case they are combined with genes having different effects, e.g. adult plant resistance. [source]

Isolation and antifungal activity of lignans from Myristica fragrans against various plant pathogenic fungi

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 9 2007
Jun Young Cho
Abstract BACKGROUND: In a search for plant extracts with potent in vivo antifungal activity against various plant diseases, we found that treatment with a methanol extract of Myristica fragrans Houttyn (nutmeg) seeds reduced the development of various plant diseases. The objectives of the present study were to isolate and determine antifungal substances from My. fragrans and to evaluate their antifungal activities. RESULTS: Three antifungal lignans were isolated from the methanol extract of My. fragrans seeds and identified as erythro -austrobailignan-6 (EA6), meso -dihydroguaiaretic acid (MDA) and nectandrin-B (NB). In vitro antimicrobial activity of the three lignans varied according to compound and target species. Alternaria alternata, Colletotrichum coccodes, C. gloeosporioides, Magnaporthe grisea, Agrobacterium tumefaciens, Acidovorax konjaci and Burkholderia glumae were relatively sensitive to the three lignans. In vivo, all three compounds effectively suppressed the development of rice blast and wheat leaf rust. In addition, EA6 and NB were highly active against the development of barley powdery mildew and tomato late blight, respectively. Both MDA and NB also moderately inhibited the development of rice sheath blight. CONCLUSION: This is the first study to demonstrate the in vitro and in vivo antifungal activities of the three lignans from My. fragrans against plant pathogenic fungi. Copyright © 2007 Society of Chemical Industry [source]

Wheat leaf rust resistance gene Lr59 derived from Aegilops peregrina

PLANT BREEDING, Issue 4 2008
G. F. Marais
Abstract An Aegilops peregrina (Hackel in J. Fraser) Maire & Weiller accession that showed resistance to mixed leaf rust (Puccinia triticina Eriks.) inoculum was crossed with, and backcrossed to, hexaploid wheat (Triticum aestivum L.). During backcrossing a chromosome segment containing a leaf rust resistance gene (here designated Lr59) was spontaneously translocated to wheat chromosome 1A. Meiotic, monosomic and microsatellite analyses suggested that the translocated segment replaced most of, or the complete, 1AL arm, and probably resulted from centromeric breaks and fusion. The translocation, of which hexaploid wheat line 0306 is the appropriate source material, provided seedling leaf rust resistance against a wide range of South African and Canadian pathotypes. [source]

Leaf rust and stripe rust resistance genes Lr54 and Yr37 transferred to wheat from Aegilops kotschyi

Identification of a molecular marker linked to an Agropyron elongatum-derived gene Lr19 for leaf rust resistance in wheat

PLANT BREEDING, Issue 3 2003
D. P. Cherukuri
Abstract The leaf rust resistance gene Lr19, transferred from Agropyron elongatum into wheat (Triticum aestivum L.) imparts resistance to all pathotypes of leaf rust (Puccinia recondita f.sp. tritici) in South-east Asia. A segregating F2 population from a cross between the leaf rust resistant parent ,HW 2046' carrying Lr19 and a susceptible parent ,Agra Local' was screened in the phytotron against a virulent pathotype 77-5 of leaf rust with the objective of identifying the molecular markers linked to Lr19. The gene was first tagged with a randomly amplified polymorphic DNA (RAPD) marker S73728. The RAPD marker linked to the gene Lr19 which mapped at 6.4 ± 0.035 cM distance, was converted to a sequence characterized amplified region (SCAR) marker. The SCAR marker (SCS73719) was specific to Lr19 and was not amplified in the near-isogenic lines (NILs) carrying other equally effective alien genes Lr9, Lr28 and Lr32 enabling breeders to pyramid Lr19 with these genes. [source]

A microsatellite marker linked to leaf rust resistance transferred from Aegilops triuncialis into hexaploid wheat

PLANT BREEDING, Issue 3 2001
M. Aghaee-Sarbarzeh
Abstract Aegilops triuncialis (UUCC) is an excellent source of resistance to various wheat diseases, including leaf rust. Leaf rust-resistant derivatives from a cross of a highly susceptible Triticum aestivum cv.,WL711' as the recurrent parent and Ae. triuncialis Ace.3549 as the donor and with and without a pair of acrocentric chromosomes were used for molecular tagging. The use of a set of sequence tagged microsatellite (STMS) markers already mapped to different wheat chromosomes unequivocally indicated that STMS marker gwm368 of chromosome 4BS was tightly linked to the Ae. triuncialis leaf rust resistance gene transferred to wheat. The presence of the Ae. Triuncialis -specific STMS gwm368 homoeoallele along with the non-polymorphic 4BS allele in the rust-resistant derivatives with and without the acrocentric chromosome indicates that the resistance has been transferred from the acrocentric chromosome to either the A or the D genome of wheat. This alien leaf rust resistance gene has been temporarily named as LrTr. [source]

Evidence for hyperparasitism of coffee rust (Hemileia vastatrix) by the entomogenous fungus, Lecanicillium lecanii, through a complex ecological web

PLANT PATHOLOGY, Issue 4 2009
J. Vandermeer
The entomogenous fungus, Lecanicillium lecanii is hyperparasitic on Hemileia vastatrix, the cause of coffee leaf rust in the laboratory, and has frequently been observed attacking it in the field. The existence of a complex ecological web involving the spatially clustered mutualism of an ant (Azteca instabilis) with a scale insect (Coccus viridis), where the scale insect was infected by L. lecanii, prompted a search for a spatial correlation between the attack of L. lecanii on the scale insect and the incidence of rust in a commercial coffee crop. A weak but statistically significant effect of hyperparasitic control of coffee rust was observed on two distinct scales: in a 45-ha plot and on a scale of approximately 10 m. It was concluded that this effect was linked to an indirect effect of the ant,coccid mutualism, where L. lecanii was a parasite of the coccid. [source]

First report of leaf rust on plum (Prunus cerasifera) by Tranzschelia pruni-spinosa var. discolor in the eastern Mediterranean region of Turkey

PLANT PATHOLOGY, Issue 2 2004
S. Soylu
No abstract is available for this article. [source]

First record of leaf rust caused by Puccinia hordei on Hordeum vulgare ssp. spontaneum in Turkey

PLANT PATHOLOGY, Issue 2 2004
H. Kavak
No abstract is available for this article. [source]

Inhibition of the development of leaf rust (Puccinia recondita) by treatment of wheat with allopurinol and production of a hypersensitive-like reaction in a compatible host

PLANT PATHOLOGY, Issue 3 2000
A. L. Ádám
The effect of allopurinol [4-hydroxypyrazolo (3,4- d) pyrimidine], a purine analogue inhibitor of xanthine oxidase (XO) enzyme, was studied in the host,pathogen combination of Triticum aestivum,Puccinia recondita f.sp. tritici. Analysis of purines and pyrimidines in the allopurinol-treated wheat seedlings showed marked accumulation of xanthine, suggesting the inplanta inhibition of XO activity. In the incompatible wheat,rust interaction application of allopurinol as a drench, even at the highest concentration (50 ,m), did not change the hypersensitive reaction phenotype; only the number of lesions was slightly reduced. Allopurinol treatment decreased the augmented rate of electrolyte leakage and lipid peroxidation associated with the hypersensitive response (HR), an effect probably related to the inhibition of rust development by allopurinol. By contrast, in the case of the compatible wheat,leaf-rust combination the reaction type was strongly affected. The formation of uredia and production of uredospores were diminished or completely inhibited depending on the concentration of allopurinol, which was applied either as a drench (3.125,50 ,m) or as a foliar spray (100,400 ,m) to plants grown in perlite. At the highest allopurinol concentration in the drench, the compatible reaction type changed to a hypersensitive-like necrotic reaction. Significant increases in electrolyte leakage and lipid peroxidation (characteristic of the HR) were found 4,6 days after infection in susceptible plants treated with allopurinol. Staining of leaf slices from allopurinol-treated and compatible rust-infected plants with Evans blue indicated cell death surrounding the pustules, while at this stage no cell death was detected in infected leaves without allopurinol treatment. The above results suggest that XO is not the main source of the generation of active oxygen species in wheat during the HR to leaf rust. [source]