Host–pathogen specificity in postseedling reaction of Linum usitatissimum to Melampsora lini

1992 ◽  
Vol 70 (6) ◽  
pp. 1168-1174 ◽  
Author(s):  
J. A. Hoes ◽  
E. O. Kenaschuk
Keyword(s):  
Linum Usitatissimum ◽  
Genetic Background ◽  
Virulence Genes ◽  
Single Gene ◽  
Adult Plant ◽  
Host Genotype ◽  
Resistance Level ◽  
Melampsora Lini ◽  
Host Pathogen ◽  
Different Levels

Eleven commercial flax cultivars and 10 race differentials, inoculated at the prebloom stage, showed significantly different levels of postseedling resistance to virulent races of flax rust. The effects of hosts and of races were significant or highly significant. Races differentiated hosts, hosts differentiated races, and host × race interaction was highly significant. Non-allelic, single-gene differences in host genotype were associated with higher levels of resistance and were ascribed to epistatic action by an L6-complex and by genes K1, M4, and N1. Epistatic action for susceptibility by gene L9 may have occurred in the race differentials Dakota (L9M) and Koto (L9P). The high aggressiveness of race 22 on 10 commercial race-differentiating hosts was correlated with possession of 26 virulence genes compared with 12–15 genes possessed by three other races. Indications are that allelism of host resistance genes and linked virulence of corresponding virulence genes, and also genetic background, were factors in host × pathogen interactions. The cultivar McGregor is a superior source of postseedling rust resistance because each of its genes K1 and L6 was associated with a high resistance level to race 22. Key words: adult plant, allelism, epistasis, flax.

scholarly journals Avena sterilis L. Genotypes as a Potential Source of Resistance to Oat Powdery Mildew

Plant Disease ◽  
2016 ◽  
Vol 100 (10) ◽  
pp. 2145-2151 ◽  
Author(s):  
Sylwia Okoń ◽  
Edyta Paczos-Grzęda ◽  
Tomasz Ociepa ◽  
Aneta Koroluk ◽  
Sylwia Sowa ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Single Gene ◽  
Screening Tests ◽  
Single Spore ◽  
Avena Sterilis ◽  
Breeding Programs ◽  
Host Pathogen ◽  
Pathogen Screening ◽  
High Level ◽  
Different Levels

The aim of the present study was to identify Avena sterilis genotypes demonstrating a high level of resistance against oat powdery mildew, using host-pathogen tests. The study was conducted on 350 A. sterilis genotypes from different parts of the world. Six single-spore isolates of Blumeria graminis (DC.) f. sp. avenae, which demonstrated different levels of virulence to control lines and cultivars, were used in host-pathogen screening tests. To confirm the resistant response of selected genotypes, 13 other isolates were used. Reactions to the isolates were grouped into three classes: resistant, intermediate, and susceptible. Susceptible cultivars Sam and Fuchs were used as controls to estimate the degree of infection. The results of the screening test showed that 10 genotypes were classified as resistant. The second test based on 13 other isolates revealed that only four of the 10 genotypes were a valuable source of resistance against powdery mildew. The identified genotypes may be used in oat breeding programs to increase the level of resistance against powdery mildew. First, however, further studies aimed at identifying whether this resistance is conditioned by a single gene or combinations of different genes are required.

Flax rust from Linum marginale: pathogenicity reactions on the Linum usitatissimum set of differential varieties

1989 ◽  
Vol 67 (11) ◽  
pp. 3187-3191 ◽  
Author(s):  
G. J. Lawrence
Keyword(s):  
Resistance Gene ◽  
Resistance Genes ◽  
Linum Usitatissimum ◽  
Virulence Genes ◽  
Avirulence Genes ◽  
Reaction Type ◽  
Melampsora Lini ◽  
Two Factors ◽  
Standard Set ◽  
Differential Varieties

Flax rust, Melampsora lini (Ehrenb.) Lév., occurs on Linum marginale Cunn., the only Linum species indigenous to Australia. Evidence suggests that the rust is native to L. marginale and is not a recent introduction. Forty-five isolates from this rust population, collected from 21 locations, were tested for reaction type on the standard set of 28 flax (L. usitatissimum) differential lines. All isolates were avirulent on the majority of differentials and only three clearly different virulence phenotypes were distinguished. This finding contrasts with the results of a companion study in which the same isolates displayed many different virulence phenotypes when tested on a set of L. marginale lines. Two factors apparently contribute to the failure of the L. usitatissimum differentials to detect most of the variation for virulence present in this rust population. First, 10 of the differentials have been reported to possess resistance gene L9 in addition to their designated gene. Since all isolates recognize the L9 gene, these differentials could make no contribution to differentiating between the isolates. Second, many of the L. usitatissimum resistance genes apparently do not occur in L. marginale and with no selection on the rust to conserve or evolve the corresponding virulence genes, the corresponding avirulence genes appear to have become, or remained, fixed in the rust population.

scholarly journals Intrapathotype Diversity for Aggressiveness and Pathogen Evolution in Cultivar Mixtures

2001 ◽  
Vol 91 (5) ◽  
pp. 500-510 ◽  
Author(s):  
Christian Lannou
Keyword(s):  
Genetic Background ◽  
Host Genotype ◽  
Pathogen Evolution ◽  
Rate Of Increase ◽  
Two Component ◽  
Host Genetic ◽  
Cost Of Virulence ◽  
Different Levels ◽  
Cultivar Mixtures

A model was developed and used to study the consequences of diversity for aggressiveness within pathotypes on pathogen evolution in two-component and four-component cultivar mixtures. It was assumed that, within a pathotype, a proportion of the isolates would have higher or lower spore efficacy than the average on a given host genetic background. Two situations were examined in which the pathogen can have either independent or negatively correlated values for spore efficacy on different cultivars. In the latter case, a pathogen genotype more aggressive than the average on a host genotype was always less aggressive on other host genotypes. In the simulations, isolates with greater aggressiveness relative to a host genotype were selected for and increased in frequency. However, because simple pathotypes always reproduced on the same host genotype whereas complex pathotypes were able to grow on several hosts, selection was faster for simple pathotypes. Pathotypes with two different levels of diversity for aggressiveness were compared with nondiversified pathotypes. In order to make comparisons, the effect of a 5 and 10% cost of virulence on the development of complex pathotypes was simulated. In general, increased diversity within pathotypes reduced the rate of increase of complex pathotypes in host mixtures, and this effect was stronger with greater frequencies of autodeposition of pathogen spores.

scholarly journals Linkage in Linum Usitatissimum and in Melampsora Lini Between Genes Controlling Host-Pathogen Reactions

1956 ◽  
Vol 9 (1) ◽  
pp. 18 ◽  
Author(s):  
GME Mayo
Keyword(s):  
Disease Resistance ◽  
Linum Usitatissimum ◽  
Susceptible Variety ◽  
Allelic Series ◽  
Critical Test ◽  
Melampsora Lini ◽  
Upper Limits ◽  
Host Pathogen

The work of FloI', the most procise published on the genetics of disease resistance in higher plant.s, is shown to establish much less t.han is claimed. His allclie series are based on one case where linkago cannot be gl'Cater than 0�3 per cent. at 0�05 lo\'n! of certainty, if t.he data (\1'0 accepted as satisfactory: in fact, they eontain several nnsatisfactory features. For the rest of Flor's evidence, upper limits of linkages between genes within his allelic series of not less than approximately 20 per cent. are possible. More critical test�s are needed, using progeny of heterozygotes buekcrossed to a universally susceptible variety.

scholarly journals Resistance to Asian soybean rust in soybean lines with the pyramided three Rpp genes

2013 ◽  
Vol 13 (1) ◽  
pp. 75-82 ◽  
Author(s):  
Naoki Yamanaka ◽  
Noelle G Lemos ◽  
Miori Uno ◽  
Hajime Akamatsu ◽  
Yuichi Yamaoka ◽  
...  
Keyword(s):  
Genetic Background ◽  
Susceptible Variety ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Soybean Line ◽  
Pathogen Population ◽  
Resistance Level ◽  
Asian Soybean Rust ◽  
High Level

In this study, the influence of genetic background on the resistance level of a soybean line carrying Rpp2, Rpp4, and Rpp5 was evaluated by backcrossing it with a susceptible variety. It was also evaluated eight lines which carry these Rpp genes against five Asian soybean rust (ASR) isolates, in order to determine the likely range of resistance against ASR isolates differing in pathogenicity. The results indicated that a high level of resistance against various ASR isolates could be retained in lines carrying the three Rpp genes in susceptible genetic backgrounds, although minor influences of plant genetic background and ASR pathogenicity to the ASR resistance could occur. Thus, lines with the pyramided three Rpp genes should be effective against a complex pathogen population consisting of diverse Phakopsora pachyrhizi isolates.

CDC Bethune flax

2002 ◽  
Vol 82 (1) ◽  
pp. 101-102 ◽  
Author(s):  
G. G. Rowland ◽  
Y. A. Hormis ◽  
K. Y. Rashid
Keyword(s):  
Linum Usitatissimum ◽  
Oil Content ◽  
Oil Quality ◽  
High Yield ◽  
Lodging Resistance ◽  
Linum Usitatissimum L ◽  
Melampsora Lini ◽  
Crop Development ◽  
Cultivar Description ◽  
Moderately Resistant

CDC Bethune, is a medium-late-maturing oilseed flax (Linum usitatissimum L.) developed by Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan. This cultivar has medium oil content, medium oil quality, medium seed size, good lodging resistance and high yield when seeded early in the Black and the Brown Soil zones of the prairies. It is immune to North American races of rust caused by Melampsora lini and moderately resistant to wilt caused by Fusarium oxysporum f. sp. lini. Key words: Flax, oilseed, Linum usitatissimum L., cultivar description

scholarly journals Yield Loss Associated with Different Levels of Stem Rust Resistance in Bread Wheat

Plant Disease ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2531-2538 ◽  
Author(s):  
Tegwe Soko ◽  
Cornelia M. Bender ◽  
Renée Prins ◽  
Zacharias A. Pretorius
Keyword(s):  
Stem Rust ◽  
Yield Loss ◽  
Field Trials ◽  
Susceptible Variety ◽  
Yield Reduction ◽  
Adult Plant ◽  
Different Types ◽  
The Mean ◽  
Disease Pressure ◽  
Different Levels

Puccinia graminis f. sp. tritici race Ug99 (syn. TTKSK) has been identified as a major threat to wheat production based on its broad virulence. Despite its importance, the effect of Ug99 on different types of resistance in wheat has not been thoroughly researched. In field trials conducted with P. graminis f. sp. tritici race PTKST (Ug99 race group) over 2 years, AUDPC differentiated the moderately susceptible variety SC Stallion (515) and susceptible entries SC Nduna (995) and Line 37-07 (1634) from those with adult plant resistance (APR). AUDPC of APR varieties W1406 (256), W6979 (399), and Kingbird (209) was higher than the mean of 25 recorded for the all stage resistant (ASR) variety SC Sky. In fungicide-protected and unprotected plots, race PTKST resulted in a mean yield loss of 21.3%, with susceptible Line 37-03 recording a 47.9% decrease in grain yield. Yield reduction in APR varieties reached 19.5% in W1406, whereas the ASR control SC Sky showed a mean loss of 6.4%. Although APR reduced the effects of stem rust on yield and yield components under conditions of high disease pressure, it did not provide the same protection as effective ASR.

Effect of level of feed intake on the performance and carcass composition of growing pigs

1972 ◽  
Vol 14 (2) ◽  
pp. 199-208 ◽  
Author(s):  
R. S. Barber ◽  
R. Braude ◽  
K. G. Mitchell ◽  
R. J. Pittman
Keyword(s):  
Feed Intake ◽  
Genetic Background ◽  
Live Weight ◽  
Growing Pigs ◽  
Carcass Composition ◽  
Large White ◽  
Enzootic Pneumonia ◽  
Litter Mate ◽  
Different Genetic Background ◽  
Different Levels

SUMMARY1. Twelve blocks of six enzootic-pneumonia-free Large White litter-mate pigs were individually fed, wet, from 20 to 92 kg live weight on six different levels of feed intake. Four groups were fed according to scales based on live weight and two were fed on a ‘semi-ad libitum’ system. One of the scales used was based on the ARC (1967) recommendations.2. Pigs on ‘semi-ad libitum’ feeding grew significantly faster than those on scale feeding although the feed: gain ratios were similar. Differences in performance between the four scale-fed groups were relatively small.3. Although treatment differences in carcass measurements were in the main small, the commercial grading results favoured the carcasses from the scale-fed pigs. The firmness of backfat assessed by thumb pressure was reduced as the level of feeding was increased.4. The results were compared with those obtained in a similar trial carried out at Shinfield in 1957 using pigs of a completely different genetic background. The general conclusions reached were similar in the two trials, that to obtain the most satisfactory overall results some form of controlled scale-feeding was necessary.

CDC Buryu oilseed flax

2020 ◽  
Author(s):  
Helen M. Booker ◽  
Gordon Rowland ◽  
Hadley R. Kutcher ◽  
khalid Y. rashid
Keyword(s):  
Linum Usitatissimum ◽  
Oil Content ◽  
Oil Quality ◽  
Black Soil ◽  
Lodging Resistance ◽  
Linum Usitatissimum L ◽  
Melampsora Lini ◽  
Crop Development ◽  
Moderately Resistant ◽  
Maturity Rating

CDC Buryu, a late maturing oilseed flax (Linum usitatissimum L.), was registered in 2016 by the Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan. This cultivar had yield (106%) comparable to CDC Bethune and a maturity rating equal to Flanders in all soil zones of the Northern Prairies. The yield advantage over CDC Bethune was greater (>8%) in the Brown soil and Black soil zones of the Northern Prairies. It had medium oil content, oil quality, and seed size and good lodging resistance. It is immune to North American rust (race 371) caused by Melampsora lini and moderately resistant to wilt caused by Fusarium oxysporum f. sp. Lini and powdery mildew caused by Oidium lini.

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