scholarly journals Heritability of Latent Period Estimated from Wild-Type and Selected Populations of Puccinia triticina

2007 ◽  
Vol 97 (8) ◽  
pp. 1022-1029 ◽  
Author(s):  
Jeffrey S. Lehman ◽  
Gregory Shaner
Keyword(s):  
Latent Period ◽  
Puccinia Triticina ◽  
Wild Type ◽  
Fitness Components ◽  
Susceptible Host ◽  
Resistance Selection ◽  
Selection Experiments ◽  
Wheat Leaf ◽  
Parasitic Fitness ◽  
Fungal Populations

Durability of partially resistant wheat cultivars to wheat leaf rust depends on the amount of genetic variation in parasitic fitness within populations of the pathogen Puccinia triticina. To assess the durability of partial resistance, selection experiments were used to explore quantitative variation in parasitic fitness of P. triticina. Fungal populations 881-WT and 882-WT were selected for shortened latent period on partially resistant cvs. CI 13277 and Sw 72469-6 for multiple generations. Fitness components were measured for wild-type and selected fungal populations. Responses to selection and selection differentials were calculated, and broad-sense, realized heritabilities for latent period were estimated for wild-type fungal populations on CI 13227 and on Sw 72469-6. Selected populations had fitness characteristics, not limited to latent period, that could provide greater fitness in nature. Generally, more cycles of selection had greater effects on fitness. In particular cases, selected populations on a partially resistant cultivar had values for latent period, uredinium area, and sporulation no different from those of a susceptible host–pathogen combination. Heritabilities of latent period of populations 881-WT and 882-WT on CI 13227 or populations 881-WT and 882-WT on Sw 72469-6 ranged from 0.65 to 0.76 and 0.17 to 0.24, respectively. Our results suggest the variation to overcome quantitative host resistance exists in extant populations of P. triticina. In addition, because more of the variation in latent period for populations of P. triticina on CI 13227 was genetic than for populations on Sw 72469-6, CI 13227 is likely to be more vulnerable to pathogen adaptation despite its exceptionally long latent period.

scholarly journals Selection of Populations of Puccinia recondita f. sp. tritici for Shortened Latent Period on a Partially Resistant Wheat Cultivar

1997 ◽  
Vol 87 (2) ◽  
pp. 170-176 ◽  
Author(s):  
Jeffrey S. Lehman ◽  
Gregory Shaner
Keyword(s):  
Growth Rate ◽  
Latent Period ◽  
Puccinia Recondita ◽  
Infection Frequency ◽  
Wheat Cultivars ◽  
Wild Type ◽  
Parasitic Fitness ◽  
Fungal Populations ◽  
Type Population ◽  
Selection Of

Wild-type fungal population 851-WT was selected for shortened latent period on cv. CI 13227 for five uredinial generations to study the adaptation of Puccinia recondita f. sp. tritici to partially resistant wheat cultivars. Differences among wild-type and selected populations for traits contributing to parasitic fitness (i.e., latent period, infection frequency, and uredinium area and growth rate) were assessed in monocyclic infection experiments on susceptible cv. Monon and partially resistant cvs. Suwon 85, Sw 72469-6, L-574-1, and CI 13227. Differences were greatest among fungal populations on cv. CI 13227. The mean latent period of selected population 851-C5 was 2 days shorter (~20%) than that of wild-type population 851-WT. In addition, uredinia of population 851-C5 expanded 40% faster and produced ~75% more urediniospores. On cv. L-574-1, the selected population was also more fit than the wild-type progenitor for initial uredinium area and growth rate and cumulative urediniospore production. In contrast to wild-type and selected populations on cvs. CI 13227 and L-574-1, selected population 851-C5 on cv. Monon produced slower expanding uredinia with fewer urediniospores than did population 851-WT on Monon. These results show that variation in the latent period of P. recondita f. sp. tritici populations is partially under genetic control and wild-type P. recondita f. sp. tritici populations contain members reproductively more fit on partially resistant wheat cultivars but not necessarily on susceptible cultivars. Such members are capable of partially overcoming quantitative host resistance.

scholarly journals Genetically Divergent Types of the Wheat Leaf Fungus Puccinia triticina in Ethiopia, a Center of Tetraploid Wheat Diversity

2016 ◽  
Vol 106 (4) ◽  
pp. 380-385 ◽  
Author(s):  
J. A. Kolmer ◽  
M. A. Acevedo
Keyword(s):  
Leaf Rust ◽  
Common Wheat ◽  
Hexaploid Wheat ◽  
Rust Fungus ◽  
Tetraploid Wheat ◽  
Low Frequency ◽  
Puccinia Triticina ◽  
Leaf Rust Resistance ◽  
Virulence Phenotype ◽  
Wheat Leaf

Collections of Puccinia triticina, the wheat leaf rust fungus, were obtained from tetraploid and hexaploid wheat in the central highlands of Ethiopia, and a smaller number from Kenya, from 2011 to 2013, in order to determine the genetic diversity of this wheat pathogen in a center of host diversity. Single-uredinial isolates were derived and tested for virulence phenotype to 20 lines of Thatcher wheat that differ for single leaf rust resistance genes and for molecular genotypes with 10 simple sequence repeat (SSR) primers. Nine virulence phenotypes were described among the 193 isolates tested for virulence. Phenotype BBBQJ, found only in Ethiopia, was predominantly collected from tetraploid wheat. Phenotype EEEEE, also found only in Ethiopia, was exclusively collected from tetraploid wheat and was avirulent to the susceptible hexaploid wheat ‘Thatcher’. Phenotypes MBDSS and MCDSS, found in both Ethiopia and Kenya, were predominantly collected from common wheat. Phenotypes CCMSS, CCPSS, and CBMSS were found in Ethiopia from common wheat at low frequency. Phenotypes TCBSS and TCBSQ were found on durum wheat and common wheat in Kenya. Four groups of distinct SSR genotypes were described among the 48 isolates genotyped. Isolates with phenotypes BBBQJ and EEEEE were in two distinct SSR groups, and isolates with phenotypes MBDSS and MCDSS were in a third group. Isolates with CCMSS, CCPSS, CBMSS, TCBSS, and TCBSQ phenotypes were in a fourth SSR genotype group. The diverse host environment of Ethiopia has selected and maintained a genetically divergent population of P. triticina.

Mapping of QTLs prolonging the latent period of Puccinia triticina infection in wheat

2004 ◽  
Vol 110 (2) ◽  
pp. 244-251 ◽  
Author(s):  
X.-Y. Xu ◽  
G.-H. Bai ◽  
B. F. Carver ◽  
G. E. Shaner ◽  
R. M. Hunger
Keyword(s):  
Latent Period ◽  
Puccinia Triticina

scholarly journals Effect of Resistance Inducing Chemicals on Wheat Leaf Rust Caused by Puccinia triticina

2013 ◽  
Vol 41 (2) ◽  
pp. 121-133
Author(s):  
Nour El-Din Soliman ◽  
Magdy Saber ◽  
Alaa Abd-Elaziz ◽  
Ibrahim Imbabi
Keyword(s):  
Leaf Rust ◽  
Puccinia Triticina ◽  
Wheat Leaf Rust ◽  
Wheat Leaf

scholarly journals Maximum likelihood estimation of fitness components in experimental evolution

2018 ◽  
Author(s):  
Jingxian Liu ◽  
Jackson Champer ◽  
Chen Liu ◽  
Joan Chung ◽  
Riona Reeves ◽  
...  
Keyword(s):  
Maximum Likelihood ◽  
Experimental Evolution ◽  
Evolutionary Dynamics ◽  
Likelihood Estimation ◽  
Loss Of Function ◽  
Wild Type ◽  
Fitness Components ◽  
Linked Gene ◽  
Males And Females

AbstractEstimating fitness differences between allelic variants is a central goal of experimental evolution. Current methods for inferring selection from allele frequency time series typically assume that evolutionary dynamics at the locus of interest can be described by a fixed selection coefficient. However, fitness is an aggregate of several components including mating success, fecundity, and viability, and distinguishing between these components could be critical in many scenarios. Here we develop a flexible maximum likelihood framework that can disentangle different components of fitness and estimate them individually in males and females from genotype frequency data. As a proof-of-principle, we apply our method to experimentally-evolved cage populations of Drosophila melanogaster, in which we tracked the relative frequencies of a loss-of-function and wild-type allele of yellow. This X-linked gene produces a recessive yellow phenotype when disrupted and is involved in male courtship ability. We find that the fitness costs of the yellow phenotype take the form of substantially reduced mating preference of wild-type females for yellow males, together with a modest reduction in the viability of yellow males and females. Our framework should be generally applicable to situations where it is important to quantify fitness components of specific genetic variants, including quantitative characterization of the population dynamics of CRISPR gene drives.

scholarly journals Isolation and Characterization of HIV-1 Isolates Resistant to Oxathiin Carboxanilide Analogues: Evaluation of Variables in the Drug Resistance Selection Process

1996 ◽  
Vol 7 (5) ◽  
pp. 261-269 ◽  
Author(s):  
T.L. Kinjerski ◽  
L.A. Pallansch ◽  
R.W. Buckheit
Keyword(s):  
Drug Resistance ◽  
Amino Acid ◽  
Reverse Transcriptase ◽  
Selection Process ◽  
Antiviral Agents ◽  
Wild Type Virus ◽  
Wild Type ◽  
Resistance Selection ◽  
Isolation And Characterization ◽  
Virus Isolates

Virus isolates resistant to a variety of structural analogues of oxathiin carboxanilide (UC84) were selected in cell culture and phenotypically and mo!ecularly characterized in order to evaluate the effects of variables in the resistance selection process. The rate of appearance of the resistant viruses and the net loss of sensitivity of the virus isolates to the selecting compound were not dependent on the selective pressure employed against wild-type virus, but were associated with structural features of the compound. Although each of the compounds rapidly selected for resistant viruses, the isolates obtained varied in their overall level of resistance, in their cross-resistance to other non-nucleoside reverse transcriptase inhibitors (NNRTIs) and in the amino acid changes present in the reverse transcriptase (RT). The mutation Y181C was most commonly observed, often with a second mutation, such as K101E or V-106A. The amino acid change L100I was also observed upon selection. In order to determine the reproducibility of the in-vitro resistance selection process, 10 isolates resistant to UC84 were independently selected in parallel cultures. Mutations detected in the RT of these isolates were varied but included the commonly reported Y181C and V106A amino acid changes, as well as unique changes K101I, K101N, K103Q, G190A, T139I and A98S. These results demonstrate that from the heterogeneous wild-type population, antiviral agents, such as the UC compounds, may select a wide variety of virus isolates with resistance-engendering amino acid changes in the RT. In addition, the results also suggest that antiviral agents may select for resistant viruses at different rates and to different extents, offering the possibility that compounds might be identified which do not readily result in high level drug resistance.

scholarly journals Physiologic Specialization of Puccinia triticina on Wheat in the United States in 2002

Plant Disease ◽  
2004 ◽  
Vol 88 (10) ◽  
pp. 1079-1084 ◽  
Author(s):  
J. A. Kolmer ◽  
D. L. Long ◽  
M. E. Hughes
Keyword(s):  
United States ◽  
Leaf Rust ◽  
Great Plains ◽  
Puccinia Triticina ◽  
The United States ◽  
Wheat Leaf Rust ◽  
Ohio Valley ◽  
Virulence Phenotype ◽  
Common Phenotype ◽  
Wheat Leaf

Collections of Puccinia triticina were obtained from rust-infected wheat leaves by cooperators throughout the United States and from surveys of wheat fields and nurseries in the Great Plains, Ohio Valley, Southeast, California, and the Pacific Northwest, in order to determine the virulence of the wheat leaf rust fungus in 2002. Single uredinial isolates (785 in total) were derived from the wheat leaf rust collections and tested for virulence phenotype on lines of Thatcher wheat that are near-isogenic for leaf rust resistance genes Lr1, Lr2a, Lr2c, Lr3, Lr9, Lr16, Lr24, Lr26, Lr3ka, Lr11, Lr17, Lr30, LrB, Lr10, Lr14a, and Lr18. In the United States in 2002, 52 virulence phenotypes of P. triticina were found. Virulence phenotype MBDS, which is virulent to resistance gene Lr17, was the most common phenotype in the United States. MBDS was found in the Southeast, Great Plains, and the Ohio Valley regions, and also in California. Phenotype MCDS, virulent to Lr17 and Lr26, was the second most common phenotype and occurred in the same regions as MBDS. Virulence phenotype THBJ, which is virulent to Lr16 and Lr26, was the third most common phenotype, and was found in the southern and northern central Great Plains region. Phenotype TLGJ, with virulence to Lr2a, Lr9, and Lr11, was the fourth most common phenotype and was found primarily in the Southeast and Ohio Valley regions. The Southeast and Ohio Valley regions differed from the Great Plains regions for predominant virulence phenotypes, which indicate that populations of P. triticina in those areas are not closely connected. The northern and southern areas of the Great Plains were similar for frequencies of predominant phenotypes, indicating a strong south to north migration of urediniospores.

scholarly journals Temporal Gene Expression Profiling of the Wheat Leaf Rust Pathosystem Using cDNA Microarray Reveals Differences in Compatible and Incompatible Defence Pathways

2007 ◽  
Vol 2007 ◽  
pp. 1-13 ◽  
Author(s):  
Bourlaye Fofana ◽  
Travis W. Banks ◽  
Brent McCallum ◽  
Stephen E. Strelkov ◽  
Sylvie Cloutier
Keyword(s):  
Leaf Rust ◽  
Metabolic Pathways ◽  
Fungal Pathogens ◽  
Puccinia Triticina ◽  
Phenylpropanoid Pathway ◽  
Altered Expression ◽  
Temporal Gene Expression ◽  
Wheat Leaf ◽  
Mock Treatment ◽  
Host Genes

In this study, we detail the construction of a custom cDNA spotted microarray containing 7728 wheat ESTs and the use of the array to identify host genes that are differentially expressed upon challenges with leaf rust fungal pathogens. Wheat cultivar RL6003 (Thatcher Lr1) was inoculated with Puccinia triticina virulence phenotypes BBB (incompatible) or TJB (7-2) (compatible) and sampled at four different time points (3, 6, 12, and 24 hours) after inoculation. Transcript expression levels relative to a mock treatment were measured. One hundred ninety two genes were found to have significantly altered expression between the compatible and incompatible reactions. Among those were genes involved in photosynthesis, the production of reactive oxygen species, ubiquitination, signal transduction, as well as in the shikimate/phenylpropanoid pathway. These data indicate that various metabolic pathways are affected, some of which might be used by RL6003 to mount a coordinated defense against an incompatible fungal pathogen.

scholarly journals Baseline Sensitivity of Natural Population and Resistance of Mutants in Phytophthora capsici to Zoxamide

2011 ◽  
Vol 101 (9) ◽  
pp. 1104-1111 ◽  
Author(s):  
Yang Bi ◽  
Xiaolan Cui ◽  
Xiaohong Lu ◽  
Meng Cai ◽  
Xili Liu ◽  
...  
Keyword(s):  
Ultraviolet Irradiation ◽  
Mycelial Growth ◽  
Laboratory Experiments ◽  
Phytophthora Capsici ◽  
Cross Resistance ◽  
Wild Type ◽  
Baseline Sensitivity ◽  
Mycelial Culture ◽  
Resistance Selection ◽  
Resistant Mutants

Laboratory experiments were conducted to determine the baseline sensitivity of Phytophthora capsici and its risk for developing resistance to zoxamide. In total, 158 P. capsici isolates were collected from China. All 158 isolates were sensitive to zoxamide, with effective concentrations for 50% inhibition of mycelial growth of 0.023 to 0.383 μg/ml and a mean of 0.114 μg/ml, which showed a skewed unimodal distribution. Zoxamide-resistant mutants of P. capsici were obtained by either treating mycelial culture and zoospores with ultraviolet irradiation or adapting a culture on zoxamide-amended plates. The frequency of resistance selection averaged 1.8 × 10–7. Resistant isolates were also derived by selfing or crossing two sexually compatible isolates, resulting in a mean selection frequency of 0.47. The resistance factor (RF) for zoxamide was 25 to 100 in P. capsici mutants. Through 10 culture transfers, the mutants maintained high levels of RF (between 14 and 134) and had almost equal fitness as their wild-type parents in mycelial growth, sporulation, and virulence. There was no cross resistance between zoxamide and either flumorph, metalaxyl, azoxystrobin, or etridiazole. Based on the results above, P. capsici can develop resistance to zoxamide, and the risk is predicted to be moderate in nature.

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