Trade-Off Between Triadimefon Sensitivity and Pathogenicity in a Selfed Sexual Population of Puccinia striiformis f. sp. Tritici

If distinct biological species are to coexist in sympatry, they must be reproductively isolated and must exploit different limiting resources. A two-niche Levene model is analysed, in which habitat preference and survival depend on underlying additive traits. The population genetics of preference and viability are equivalent. However, there is a linear trade-off between the chances of settling in either niche, whereas viabilities may be constrained arbitrarily. With a convex trade-off, a sexual population evolves a single generalist genotype, whereas with a concave trade-off, disruptive selection favours maximal variance. A pure habitat preference evolves to global linkage equilibrium if mating occurs in a single pool, but remarkably, evolves to pairwise linkage equilibrium within niches if mating is within those niches—independent of the genetics. With a concave trade-off, the population shifts sharply between a unimodal distribution with high gene flow and a bimodal distribution with strong isolation, as the underlying genetic variance increases. However, these alternative states are only simultaneously stable for a narrow parameter range. A sharp threshold is only seen if survival in the ‘wrong’ niche is low; otherwise, strong isolation is impossible. Gene flow from divergent demes makes speciation much easier in parapatry than in sympatry.

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Virulence and Simple Sequence Repeat Marker Segregation in a Puccinia striiformis f. sp. tritici Population Produced by Selfing a Chinese Isolate on Berberis shensiana

Phytopathology ◽

10.1094/phyto-07-15-0162-r ◽

2016 ◽

Vol 106 (2) ◽

pp. 185-191 ◽

Cited By ~ 27

Author(s):

Yuan Tian ◽

Gangming Zhan ◽

Xianming Chen ◽

Angkana Tungruentragoon ◽

Xia Lu ◽

...

Keyword(s):

Stripe Rust ◽

Puccinia Striiformis ◽

Stripe Rust Resistance ◽

Chinese Isolate ◽

Wheat Line ◽

Sexual Population ◽

Parental Isolate ◽

New Races ◽

Simple Sequence ◽

Rust Resistance Genes

Puccinia striiformis f. sp. tritici, the causal agent of wheat stripe rust, frequently produces new races overcoming resistance in wheat cultivars. A recently identified race, V26 with virulence to Yr26 and many other stripe rust resistance genes, has a high potential to cause epidemics in China. In this study, teliospores from a single-urediniospore isolate of V26 (Pinglan 17-7) produced on the wheat line 92R137 (Yr26) were used to produce a sexual population through selfing by infecting Berberis shensiana plants under controlled conditions. One hundred and eighteen progeny isolates and the parental isolate were phenotyped for virulence/avirulence on 24 Yr gene lines of wheat. These progeny isolates were all avirulent to Yr5, Yr8, Yr15, and YrTr1 and virulent to Yr1, Yr2, Yr7, Yr9, Yr10, Yr17, Yr24, Yr25, Yr26, YrA, YrExp2, and YrV23, indicating that the parental isolate is homozygous avirulent or homozygous virulent at these loci. The progeny population segregated for avirulence to Yr6, Yr43, and YrSP at one locus (3 avirulent:1 virulent ratio); for virulence to Yr27 and Yr28 at one locus (3 virulent:1 avirulent); and for Yr4, Yr32, and Yr44 at two loci (15 virulent:1 avirulent). Among the eight segregating avirulence/virulence loci, association was found between virulence to Yr4 and Yr32, as well as between virulence to Yr6 and Yr43 based on χ2 tests. From 82 genotypically different progeny isolates, 24 pathotypes and 82 multilocus genotypes were identified. The results show that a highly diverse population can be produced from a single isolate by selfing on a barberry plant and sexually produced population can be used to genetically characterize virulence of the stripe rust pathogen.

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An Avirulence Gene Cluster in the Wheat Stripe Rust Pathogen (Puccinia striiformis f. sp. tritici) Identified through Genetic Mapping and Whole-Genome Sequencing of a Sexual Population

mSphere ◽

10.1128/msphere.00128-20 ◽

2020 ◽

Vol 5 (3) ◽

Author(s):

Chongjing Xia ◽

Yu Lei ◽

Meinan Wang ◽

Wanquan Chen ◽

Xianming Chen

Keyword(s):

Whole Genome Sequencing ◽

Gene Cluster ◽

Genome Sequencing ◽

Genetic Map ◽

Reference Genome ◽

Puccinia Striiformis ◽

Whole Genome ◽

High Quality ◽

Sexual Population ◽

Content Type

ABSTRACT Puccinia striiformis f. sp. tritici, the causal agent of wheat stripe (yellow) rust, is an obligate, biotrophic fungus. It was difficult to study the genetics of the pathogen due to the lack of sexual reproduction. The recent discovery of alternate hosts for P. striiformis f. sp. tritici makes it possible to study inheritance and map genes involved in its interaction with plant hosts. To identify avirulence (Avr) genes in P. striiformis f. sp. tritici, we developed a segregating population by selfing isolate 12-368 on barberry (Berberis vulgaris) plants under controlled conditions. The dikaryotic sexual population segregated for avirulent/virulent phenotypes on nine Yr single-gene lines. The parental and progeny isolates were whole-genome sequenced at >30× coverage using Illumina HiSeq PE150 technology. A total of 2,637 high-quality markers were discovered by mapping the whole-genome sequencing (WGS) reads to the reference genome of strain 93-210 and used to construct a genetic map, consisting of 41 linkage groups, spanning 7,715.0 centimorgans (cM) and covering 68 Mb of the reference genome. The recombination rate was estimated to be 1.81 ± 2.32 cM/10 kb. Quantitative trait locus analysis mapped six Avr gene loci to the genetic map, including an Avr cluster harboring four Avr genes, AvYr7, AvYr43, AvYr44, and AvYrExp2. Aligning the genetic map to the reference genome identified Avr candidates and narrowed them to a small genomic region (<200 kb). The discovery of the Avr gene cluster is useful for understanding pathogen evolution, and the identification of candidate genes is an important step toward cloning Avr genes for studying molecular mechanisms of pathogen-host interactions. IMPORTANCE Stripe rust is a destructive disease of wheat worldwide. Growing resistant cultivars is the most effective, easy-to-use, economical, and environmentally friendly strategy for the control of the disease. However, P. striiformis f. sp. tritici can produce new virulent races that may circumvent race-specific resistance. Therefore, understanding the genetic basis of the interactions between wheat genes for resistance and P. striiformis f. sp. tritici genes for avirulence is useful for improving cultivar resistance for more effective control of the disease. This study developed a high-quality map that facilitates genomic and genetic studies of important traits related to pathogen pathogenicity and adaptation to different environments and crop cultivars carrying different resistance genes. The information on avirulence/virulence genes identified in this study can be used for guiding breeding programs to select combinations of genes for developing new cultivars with effective resistance to mitigate this devastating disease.

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A Flow-Preserving Algorithm for the Time-Cost Trade-Off Problem

IIE Transactions ◽

10.1080/05695558208974589 ◽

1982 ◽

Vol 14 (2) ◽

pp. 109-113 ◽

Cited By ~ 4

Author(s):

Suleyman Tufekci

Keyword(s):

Time Cost ◽

Trade Off

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Dual Goals for Speed and Accuracy on the Same Performance Task

Journal of Personnel Psychology ◽

10.1027/1866-5888/a000063 ◽

2012 ◽

Vol 11 (3) ◽

pp. 118-126 ◽

Cited By ~ 3

Author(s):

Olive Emil Wetter ◽

Jürgen Wegge ◽

Klaus Jonas ◽

Klaus-Helmut Schmidt

Keyword(s):

Memory Scanning ◽

Performance Task ◽

Performance Tasks ◽

Trade Off ◽

Test Experiment ◽

Trade Offs ◽

New Finding ◽

Sternberg Paradigm ◽

Speed Accuracy ◽

Speed And Accuracy

In most work contexts, several performance goals coexist, and conflicts between them and trade-offs can occur. Our paper is the first to contrast a dual goal for speed and accuracy with a single goal for speed on the same task. The Sternberg paradigm (Experiment 1, n = 57) and the d2 test (Experiment 2, n = 19) were used as performance tasks. Speed measures and errors revealed in both experiments that dual as well as single goals increase performance by enhancing memory scanning. However, the single speed goal triggered a speed-accuracy trade-off, favoring speed over accuracy, whereas this was not the case with the dual goal. In difficult trials, dual goals slowed down scanning processes again so that errors could be prevented. This new finding is particularly relevant for security domains, where both aspects have to be managed simultaneously.

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