The genetics of pathogenic aggressiveness in three dikaryons of Ustilago hordei

1984 ◽  
Vol 62 (6) ◽  
pp. 1209-1219 ◽  
Author(s):  
C. E. Caten ◽  
C. Person ◽  
J. V. Groth ◽  
S. J. Dhahi
Keyword(s):  
Mating Type ◽  
Opposite Mating Type ◽  
Gene Effects ◽  
Genetic Determination ◽  
Ustilago Hordei ◽  
Number Of Genes ◽  
Polygenic System ◽  
New Races ◽  
Pathogen Populations

The genetic determination of a quantitative component of pathogenicity, aggressiveness, was examined in progeny populations derived from three parent dikaryons of Ustilago hordei. Aggressiveness was assessed as the proportion of smutted plants produced from inoculated seed of a compatible barley cultivar. The parents differed in their origins and cultural histories and this was reflected in the variability of their progenies. A standard race-10 strain appeared to be homozygous for genes affecting aggressiveness, while a dikaryon produced by mating two unrelated sporidia was heterozygous and produced highly variable progeny populations. In these populations, aggressiveness was determined by a polygenic system which involved both additive and dominance gene effects. It was not possible to estimate the number of genes involved, but segregation was apparent in individual tetrads. Furthermore, a difference between opposite mating-type segregants suggested the presence of a factor which affected aggressiveness and was linked to mating type. The dominance effects were ambidirectional suggesting that genotypes giving an intermediate level of aggressiveness are the most fit. The aggressiveness of a pathogen strain is an important factor determining the severity of epidemics on compatible hosts. It is also a major component of fitness and may influence the frequency of virulence factors in pathogen populations and the evolution of new races.

scholarly journals Temporal Genetic Dynamics of an Experimental, Biparental Field Population of Phytophthora capsici

2016 ◽  
Author(s):  
Maryn O. Carlson ◽  
Elodie Gazave ◽  
Michael A. Gore ◽  
Christine D. Smart
Keyword(s):  
Mating Type ◽  
Phytophthora Capsici ◽  
Haplotype Frequency ◽  
Experimental System ◽  
Experimental Population ◽  
Evolutionary Potential ◽  
Opposite Mating Type ◽  
Generational Shift ◽  
Frequency Changes ◽  
Pathogen Populations

AbstractDefining the contributions of dispersal, reproductive mode, and mating system to the population structure of a pathogenic organism is essential to estimating its evolutionary potential. After introduction of the devastating plant pathogen, Phytophthora capsici, into a grower’s field, a lack of aerial spore dispersal restricts migration. Once established, coexistence of both mating types results in formation of overwintering recombinant oospores, engendering persistent pathogen populations. To mimic these conditions, in 2008, we inoculated a field with two P. capsici isolates of opposite mating type. We analyzed pathogenic isolates collected in 2009-13 from this experimental population, using genome-wide single-nucleotide polymorphism markers. By tracking heterozygosity across years, we show that the population underwent a generational shift; transitioning from exclusively F1 in 2009-10; mixed generational in 2011; and ultimately all inbred in 2012-13. Survival of F1 oospores, characterized by heterozygosity excess, coupled with a low rate of selfing, delayed declines in heterozygosity due to inbreeding and attainment of equilibrium genotypic frequencies. Large allele and haplotype frequency changes in specific genomic regions accompanied the generational shift, representing putative signatures of selection. Finally, we identified an approximately 1.6 Mb region associated with mating type determination, constituting the first detailed genomic analysis of a mating type region (MTR) in Phytophthora. Segregation patterns in the MTR exhibited tropes of sex-linkage, where maintenance of allele frequency differences between isolates of opposite mating type was associated with elevated heterozygosity despite inbreeding. Characterizing the trajectory of this experimental system provides key insights into the processes driving persistent, sexual pathogen populations.

scholarly journals Inheritance of germination vigour in sugar beet sterility maintainers and their diallel hybrids

2018 ◽  
Vol 23 ◽  
pp. 74-79
Author(s):  
M. O. Kornieieva ◽  
P. I. Vakulenko ◽  
L. S. Andrieieva ◽  
S. M. Tymchyshyn
Keyword(s):  
Seed Germination ◽  
Female Parent ◽  
Diallel Analysis ◽  
Gene Effects ◽  
Genetic Determination ◽  
Average Value ◽  
Cytoplasmic Effects ◽  
Degree Of Dominance ◽  
Genetic Value

Aim. To determine the degree of dominance of the “seed germination” sign and combination ability of sterility maintainers using diallel analysis. Methods. Hybridization of sterility maintainers was arranged as diallel crosses. Genetic determination of the sign was determined in accordance with Heyman’s method. Results. Used in crossing sterility maintainer lines have been studied in terms of their productivity in previous variety tests. D. The dominant inheritance of “seed germination” sign in diallel hybrids was determined as following: in the structure of the sign variability 43 % of cross combinations inherited this sign as positive dominance. Genetic determination of the “synergy of germination” sign was determined by the effects of combination ability. The additive effect of the female parent was assessed at 18.4 %, in male parent at 18.1 %, while the nonadditive effect of interaction between the components was at 40.7 % The influence of cytoplasmic effects amounted to 22,7 %. Selected were the best lines in specific pairs; their genetic value was studied as the average value of heterosis in many crossings involving specific lines. Conclusions. When forming sources of improved signs it is advisable to consider the cytoplasmic gene effects, which share is estimated at 22.7 %. The best lines in terms of general combination ability for seed germination found to be sterility maintainers Ot 1 and Ot 2. Keywords: sterility maintainers, combination ability, seed germination, additive, non-additive, and reciprocal effects.

Improved media for testing the mating reaction and genetic complementation of Ustilago hordei

1992 ◽  
Vol 70 (4) ◽  
pp. 788-793 ◽  
Author(s):  
Alfredo D. Martinez-Espinoza ◽  
Karla J. Dugan ◽  
Michael E. Bjarko ◽  
John E. Sherwood
Keyword(s):  
Mating Type ◽  
Activated Charcoal ◽  
Rapid Identification ◽  
Sexual Cycle ◽  
Mating Test ◽  
Opposite Mating Type ◽  
Mating Reaction ◽  
Ustilago Hordei ◽  
Key Words Barley ◽  
The Stability

The sexual cycle of Ustilago hordei, which results in the formation of teliospores, requires growth on its barley host for completion. However, the early steps of mating, including conjugation and the formation of dikaryotic mycelium, can occur on artificial media. The addition of activated charcoal to a variety of media enhanced the stability and intensity of the mating reaction as measured by mycelium formation. The incubation time at which the strongest mating reaction occurred was also reduced. The dikaryotic nature of the mycelia that resulted from mating on charcoal-containing media was confirmed by fluorescence microscopy. Complementation assays using minimal medium containing activated charcoal demonstrated allelism of mutations in auxotrophic sporidial strains of opposite mating type. The ease and reliability of this mating test allow for rapid identification of the mating type of unknown isolates and progeny of crosses, as well as providing a dependable procedure for performing complementation tests. Key words: barley, covered smut, Hordeum vulgare, mating type.

ESCAPE FROM MATING-TYPE INCOMPATIBILITY IN BISEXUAL (A + a) NEUROSPORA HETEROKARYONS

1975 ◽  
Vol 17 (3) ◽  
pp. 441-449 ◽  
Author(s):  
A. M. DeLange ◽  
A. J. F. Griffiths
Keyword(s):  
Mating Type ◽  
Loss Of Function ◽  
Wild Type ◽  
Opposite Mating Type ◽  
Type Locus ◽  
Heterokaryon Incompatibility ◽  
Recessive Mutant ◽  
Type Rate ◽  
Wild Type Rate ◽  
Incompatibility Locus

In Neurospora crassa, strains of opposite mating type generally do not form stable heterokaryons because the mating type locus acts as a heterokaryon incompatibility locus. However, when one A and one a strain, having complementing auxotrophic mutants, are placed together on minimal medium, growth may occur, although the growth is generally slow. In this study, escape from such slow growth to that at a wild type or near-wild type rate was observed. The escaped cultures are stable heterokaryons, mostly having lost the mating type allele function from one component nucleus, so that the nuclear types are heterokaryon compatible. Either A or a mating type can be lost. This loss of function has been attributed to deletion since only one nuclear type could be recovered in all heterokaryons except one, but deletion spanning adjacent loci has been directly demonstrated in a minority of cases. Alternatively when one component strain is tol and the other tol+ (tol being a recessive mutant suppressing the heterokaryon incompatibility associated with mating type), escape may occur by the deletion or mutation of tol+, also resulting in heterokaryon compatibility. An induction mechanism for escape is speculated upon.

scholarly journals Relationship Between Root and Yield Related Morphological Characters in Pea (Pisum Sativum L.)

2014 ◽  
Vol 66 (1) ◽  
pp. 3-15
Author(s):  
Sylwia Ciaglo-Androsiuk
Keyword(s):  
Root System ◽  
Morphological Traits ◽  
Lateral Roots ◽  
Morphological Characters ◽  
Yield Potential ◽  
Cultivated Plants ◽  
Genetic Determination ◽  
Canonical Correlations ◽  
Effect On Yield

AbstractRelation between morphological traits of the root system and yield related traits is an important issue concerning efforts aiming at improving of ideotype of cultivated plants species, including pea. In this paper, to analyse the dependency between traits describing the root system morphology and yield potential, Person’s andSpearman's_correlations as well as canonical correlations were used.Root system was analyzed in 14 and 21 day-old seedlings growing in blotting-paper cylinders. Yield potential of pea was analysed in a field experiment. Results of Person’s and Spearman's_correlations revealed that number of lateral roots and lateral roots density were correlated witch yield related traits. Correlation between root length and shoot length was observed only for 14 day-old seedlings. The result of canonical correlations revealed that number of lateral roots and lateral roots density had the largest effect on yield related traits. This work highlights, that in order to improve the yield of pea it might become necessary to understand genetic determination of morphological traits of the root system, especially number of lateral roots.

scholarly journals A Co-Association Network Analysis of the Genetic Determination of Pig Conformation, Growth and Fatness

PLoS ONE ◽  
2014 ◽  
Vol 9 (12) ◽  
pp. e114862 ◽  
Author(s):  
Anna Puig-Oliveras ◽  
Maria Ballester ◽  
Jordi Corominas ◽  
Manuel Revilla ◽  
Jordi Estellé ◽  
...  
Keyword(s):  
Network Analysis ◽  
Association Network ◽  
Genetic Determination

GENETICS AND METABOLISM

PEDIATRICS ◽  
1960 ◽  
Vol 25 (4) ◽  
pp. 565-571
Author(s):  
Barton Childs
Keyword(s):  
Mutant Gene ◽  
Human Populations ◽  
Affected Patient ◽  
Adrenal Hyperplasia ◽  
Genetic Determination ◽  
The Subject ◽  
Definition Of ◽  
Genetically Determined ◽  
Or Genes

IT IS the part of wisdom when about to give a dissertation which one hopes will at once instruct and entertain, to provide at the outset some definition of the subject matter. Genetics is the study of the heritable components of variation; the heritable factors which determine the range or extent of diversity. So, genetics is concerned with heritable differences and likenesses between individuals and between species. One emphasizes the differences because one can be certain of genetic determination of a particular characteristic only when it exists in a population in two or more alternative forms. It is the variants which catch the eye and hold the attention of the investigator, and which by their presence suggest more than one form of the gene or genes which determine that particular characteristic. I would like in what follows to present some examples of investigations of some aspects of genetics in human populations. ADRENAL HYPERPLASIA Several years ago Dr. Melvin Grumbach and I studied the genetics of adrenal hyperplasia, using as our material the patients of Dr. Lawson Wilkins. Since the disease occurs in more than one member of a sibship and since parents are unaffected, we suspected that it was genetically determined and that the affected patient possessed a double dose of a mutant gene; that is, the characteristic was recessive.

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