Quantitative genetics of disease incidence in Ustilago hordei controlled by virulence and aggressiveness genes

1991 ◽  
Vol 69 (2) ◽  
pp. 420-427 ◽  
Author(s):  
David D. Pope ◽  
Conrad F. Wehrhahn
Keyword(s):  
Disease Incidence ◽  
Additive Genetic Variance ◽  
Virulence Gene ◽  
Supporting Evidence ◽  
Gene Effects ◽  
Barley Cultivars ◽  
Weak Evidence ◽  
Ustilago Hordei ◽  
Selection For ◽  
Maximal Expression

Biometric analyses of variability in the disease incidence phenotype were performed using three F2 dikaryotic populations of the smut fungus Ustilago hordei (Pers.) Lagerh. on barley cultivars 'Trebi' (partially resistant) and 'Odessa' (universal suscept). The variance component involving interactions between segregating genes of U. hordei and environmental factors made the largest contribution towards the disease incidence on both cultivars. Additive and nonadditive (dominant and epistatic) gene effects contributed significantly to total disease incidence variation on both 'Trebi' and 'Odessa'. Heritability (additive genetic variance) was 2.5 times higher on 'Trebi' than on 'Odessa', and nonadditive variance effects were higher on 'Odessa' than on 'Trebi' by a factor of 1.5. Five effective factors were estimated to be segregating in the F2 populations; the virulence gene and four agressiveness factors. It is hypothesized that certain aggressiveness polygenes interact either with at least one other aggressiveness polygene or with the virulence gene. Analysis of variance–covariance provided supporting evidence for the epistatic activity of some genes and weak evidence for possible previous selection for intermediate optimal rather than maximal expression of the disease incidence phenotype. Key words: Ustilago hordei, aggressiveness, polygenes, disease incidence, smut.

Genetic variation and correlation among yield and quality traits in cocksfoot (Dactylis glomerata L.)

2007 ◽  
Vol 145 (6) ◽  
pp. 599-610 ◽  
Author(s):  
A. JAFARI ◽  
H. NASERI
Keyword(s):  
Dry Matter ◽  
Additive Genetic Variance ◽  
Heading Date ◽  
Dactylis Glomerata ◽  
Tiller Number ◽  
Water Soluble ◽  
Quality Traits ◽  
Gene Effects ◽  
Yield And Quality ◽  
Selection For

SUMMARYThe objective of the present research was to study the genetic variability for total dry matter (DM) yield, tiller number, heading date and three quality traits, namely content of digestible dry matter (DDM), water-soluble carbohydrate (WSC) and crude protein (CP), in cocksfoot (Dactylis glomerata L.). Twenty-five parents were randomly chosen from a genetically broad-based population, and their respective half-sib (HS) families were generated. Clonally-propagated parents and their HS family seeds were grown as individual plants using a randomized complete block design with two replications in Alborz Research Center, Karaj, Iran, during 2002–04. The results of combined analyses over 2 years showed significant variances between clonal parents for all traits except CP. In the HS generation, between-family variances were only significant for tiller number, heading date and WSC. Clone×year (S2GY) and family×year (S2FY) interactions were significant for all traits except for WSC in HS families. The estimates of broad-sense heritability (h2b) were moderate to high for all traits (h2b=0·37–0·69), except CP. Narrow-sense heritability (h2n) estimates from analyses of progenies and from regression of HS progenies on parents (h2op) were moderate, relatively the same values as h2b for heading date, tiller number and WSC, which suggested that additive genetic variance was the main component controlling these traits. For DM yield and DDM, h2n and h2op estimates were low, whereas h2b estimates were moderate, which suggested that both additive and non-additive gene effects played an important role in the genetic regulation of these traits. Genetic correlations among CP with both WSC and DDM were generally negative, whereas WSC was positively correlated with DDM and tiller number. The genetic correlation among DM yield with DDM was weak and inconsistent and, in general, negative. DM yield had negative and positive correlation with heading date and tiller number, respectively. It was concluded that there was significant variation and moderate heritability for most traits in the cocksfoot populations evaluated to improve yield and quality traits. Selection for high WSC is a means to improve quality in general. The data also indicate that response to combined selection for both DDM and DM yield should be possible. Selection for DDM alone could result in reduction in yield.

MASS SELECTION FOR POST-WEANING GROWTH IN SWINE. IV. SELECTION RESPONSE AND CONTROL POPULATION STABILITY

1976 ◽  
Vol 56 (4) ◽  
pp. 783-790
Author(s):  
G. W. RAHNEFELD ◽  
I. GARNETT
Keyword(s):  
Additive Genetic Variance ◽  
Average Daily Gain ◽  
Selection Response ◽  
Relative Magnitude ◽  
Control Population ◽  
Mass Selection ◽  
Gene Effects ◽  
Selection For ◽  
And Control ◽  
Daily Gain

Recurrent mass selection for post-weaning average daily gain was practiced for 11 generations in a population of Lacombe swine. Response to selection was assessed from predicted response, 0.241 ± 0.023 kg; observed response, 0.146 ± 0.018 kg; estimated heritability, 0.327 ± 0.031; and realized heritability, 0.198 ± 0.016. Observed response was estimated to be 0.61 of the predicted. Examination of additive genetic variance, selection differentials, drift variance, inbreeding and regression of post-weaning average daily gain on generation time indicated that the pedigreed Yorkshire control population served as an adequate control. Gene effects were not found to be dependent on the sex of the organism as assessed by the genetic correlation between sexes, covariance between half-sib family means and the relative magnitude of parent–offspring-based estimates of heritability.

scholarly journals SELECTION FOR BLOOD PRESSURE LEVELS IN MICE

Genetics ◽  
1974 ◽  
Vol 76 (3) ◽  
pp. 537-549
Author(s):  
Gunther Schlager
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Population Bottleneck ◽  
Control Line ◽  
Selected Lines ◽  
High Line ◽  
Selection For ◽  
Random Control

ABSTRACT Response to two-way selection for systolic blood pressure was immediate and continuous for about eight generations. In the twelfth generation, the High males differed from the Low males by 38 mmHG; the females differed by 39 mmHg. There was little overlap between the two lines and they were statistically significant from each other and from the Random control line. There appeared to be no more additive genetic variance in the eleventh and twelfth generations. Causes for the cessation of response are explored. This is probably due to a combination of natural selection acting to reduce litter sizes in the Low line, a higher incidence of sudden deaths in the High line, and loss of favorable alleles as both selection lines went through a population bottleneck in the ninth generation.—In the eleventh generation, the selected lines were used to produce F1, F2, and backcross generations. A genetic analysis yielded significant additive and dominance components in the inheritance of systolic blood pressure.

scholarly journals Screening of French Bean (Phaseolus vulgaris L.) Genotypes against Alternaria Leaf Spot Caused by (Alternaria alternata) under Dryland Conditions of Kashmir

2021 ◽  
pp. 25-30
Author(s):  
Sabiya Bashir ◽  
Mohammad Najeeb Mughal ◽  
Zahida Rashid ◽  
Shabeena Majid ◽  
Sabeena Naseer ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Leaf Spot ◽  
Disease Incidence ◽  
French Bean ◽  
Phaseolus Vulgaris L ◽  
Dryland Agriculture ◽  
Disease Reaction ◽  
The Mean ◽  
Selection For ◽  
Resistant Genotypes

Sixty-three genotypes of  french bean was screened against leaf spot (Alternaria  alternata) in sick plots at Research Farm of Dryland Agriculture Research Srinagar, Rangreth during  Kharif  2018 and 2019. The highest mean disease incidence ranged from 0.00 to 85.00 per cent  with  the mean disease intensity ranged from 0.00 to 53.26 per cent .One genotype namely  ‘Local Pulwama’ was highly susceptible in their disease reaction. Among the screened germplasm, ‘Highly Resistant’ genotypes was SKU-R-601, SKUA-R-105, SKU-R-927, DARS-25, DARS-66, DARS-R-615,  while as ‘Susceptible’ genotypes was  DARS-8, DARS-12,  DARS-11, SKUAST-R-155, SKU-R-928, DARS-7, DARS-R-4, Bhaderwah (L),  Local  Kupwara black and Raj Jawala. Local Pulwama was found to be a highly susceptible (HS) genotype.  Twenty nine genotypes namely., DARS-16, DARS-9, DARS-54, DARS-39, VL-125, DARS-63, ENTO-504, SKUAST-204,SKU-R-925, DARS-60, DARS-109, DARS-43, DARS-44, SKU-R-23, DARS-4, DARS-74, SKU-R-105, DARS-40, DARS-23, DARS-18, SKU-R-71, WB-341, SKU-R-605, Uri local, Shopian (L), SKU-R-23, DARS-71, SSGB-729, DARS-R-19 showed resistant reaction to disease. The selection for resistance was based on the reaction of varieties on leaves.

Chemical control of loose smut (Ustilago segetum var. tritici) of barley and the effects of cultivar and environment on disease incidence

1991 ◽  
Vol 31 (3) ◽  
pp. 373
Author(s):  
R Loughman ◽  
EJ Speijers ◽  
GJ Thomas ◽  
DJ Ballinger
Keyword(s):  
Western Australia ◽  
Chemical Control ◽  
Disease Incidence ◽  
Field Trials ◽  
Loose Smut ◽  
High Rainfall ◽  
Barley Cultivars ◽  
Control Disease ◽  
Moderately Resistant ◽  
Very High

The reasons for an increase in barley loose smut in high rainfall areas of Western Australia were investigated in field trials from 1986 to 1988 by examining the effects of environment, cultivar and adequacy of chemical control. Disease was 4-18 times greater in 2 seed lines produced in very high rainfall areas (>750 mm/year) compared with that produced in high (450-750 mm/year) or low (<325 mm/year) rainfall areas. The effectiveness of 5 fungicide seed treatments was assessed. No fungicide seed treatment controlled disease completely. Triadimenol at 225 mg a.i./kg and carboxin at 940 mg a.i./kg were most effective, providing 93-96% disease control. Treatments were significantly (P<0.01) less effective in high rainfall areas of Western Australia. Barley cultivars released recently in Western Australia were found to be susceptible to loose smut; we suggest that the replacement of the moderately resistant Dampier with these cultivars has contributed to an increased incidence of disease.

Patterns in the evolution of nares size and secondary palate length in anomodont therapsids (Synapsida): implications for hypoxia as a cause of end-Permian tetrapod extinctions

2008 ◽  
Vol 82 (3) ◽  
pp. 528-542 ◽  
Author(s):  
Kenneth D. Angielczyk ◽  
Melony L. Walsh
Keyword(s):  
Atmospheric Oxygen ◽  
Term Trend ◽  
Weak Evidence ◽  
Secondary Palate ◽  
Respiratory Efficiency ◽  
Rigorous Study ◽  
Selection For ◽  
Long Term Trend ◽  
Do So

Seemingly consistent proportional differences in several palatal structures have been noted between Permian and Triassic anomodont therapsids for nearly a century. These patterns have been cited as evidence in support of a decline in atmospheric oxygen concentrations that may have contributed to end-Permian terrestrial extinctions. However, it is not known whether the observed differences are significant, or whether they stem from continued directional selection. If they are not significant, or if their timing does not match that proposed for the oxygen decline, support for the hypoxia-based extinction scenario would be weakened. We tested whether the internal nares and bony secondary palate, two palatal features proposed to be related to respiratory efficiency, are significantly larger in Triassic anomodonts, and whether the variation can be attributed to a long-term tendency for increase. Results based on raw data indicate that Triassic anomodonts have significantly larger secondary palates than Permian anomodonts. They also have significantly larger internal nares, but only when primitive, morphologically-divergent specimens are not considered. Although nares and palate size are correlated with stratigraphic occurrence, available data reject the hypothesis that the observed differences were the result of a long-term trend. Most of these findings are consistent with the predictions of the hypoxia scenario. However, removing the effects of body size and phylogeny causes some of the differences to break down, indicating that if selection for increased respiratory efficiency affected these characters, it was most likely not the only factor to do so. Therefore, the characters provide only weak evidence in support of the hypoxia scenario, and we recommend against their use for this purpose. Our results emphasize the need for caution when invoking presumed differences between Permian and Triassic vertebrates as support for hypoxia, or other extinction scenarios, without a rigorous study of the character(s) in question.

GENETIC CONTROL OF VIRULENCE IN USTILAGO HORDEI. II. SEGREGATIONS FOR HIGHER LEVELS OF VIRULENCE

1971 ◽  
Vol 13 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Gurmel Sidhu ◽  
Clayton Person
Keyword(s):  
Genetic Control ◽  
Virulence Genes ◽  
Barley Cultivars ◽  
Ustilago Hordei

Genetics of virulence of Ustilago hordei towards five barley cultivars (Excelsior, Vantage, Hannchen, Trebi and Lion) was investigated. Two genes, Uhv-1 and Uhv-2, were identified; Uhv-2 was effective on Excelsior, and Uhv-1 on both Hannchen and Vantage. The virulence genes were both recessive.

scholarly journals The Locus of Enterocyte Effacement (LEE)-Encoded Regulator Controls Expression of Both LEE- and Non-LEE-Encoded Virulence Factors in Enteropathogenic and EnterohemorrhagicEscherichia coli

2000 ◽  
Vol 68 (11) ◽  
pp. 6115-6126 ◽  
Author(s):  
Simon J. Elliott ◽  
Vanessa Sperandio ◽  
Jorge A. Girón ◽  
Sooan Shin ◽  
Jay L. Mellies ◽  
...  
Keyword(s):  
Gene Expression ◽  
Virulence Gene ◽  
Global Regulator ◽  
Lesion Formation ◽  
Virulence Gene Expression ◽  
E Coli ◽  
Secretion Pathway ◽  
Regulatory Cascade ◽  
Enterocyte Effacement ◽  
Maximal Expression

ABSTRACT Regulation of virulence gene expression in enteropathogenicEscherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) is incompletely understood. In EPEC, the plasmid-encoded regulator Per is required for maximal expression of proteins encoded on the locus of enterocyte effacement (LEE), and a LEE-encoded regulator (Ler) is part of the Per-mediated regulatory cascade upregulating the LEE2, LEE3, andLEE4 promoters. We now report that Ler is essential for the expression of multiple LEE-located genes in both EPEC and EHEC, including those encoding the type III secretion pathway, the secreted Esp proteins, Tir, and intimin. Ler is therefore central to the process of attaching and effacing (AE) lesion formation. Ler also regulates the expression of LEE-located genes not required for AE-lesion formation, including rorf2, orf10,rorf10, orf19, and espF, indicating that Ler regulates additional virulence properties. In addition, Ler regulates the expression of proteins encoded outside the LEE that are not essential for AE lesion formation, including TagA in EHEC and EspC in EPEC. Δler mutants of both EPEC and EHEC show altered adherence to epithelial cells and express novel fimbriae. Ler is therefore a global regulator of virulence gene expression in EPEC and EHEC.

IDENTICAL GENES FOR VIRULENCE IN THE SMUTS USTILAGO HORDEI AND U. NIGRA, AND INHERITANCE OF VIRULENCE ON THE BARLEY CULTIVARS KEYSTONE AND CONQUEST

1974 ◽  
Vol 54 (2) ◽  
pp. 253-257 ◽  
Author(s):  
R. A. FULLERTON ◽  
J. NIELSEN
Keyword(s):  
Hordeum Vulgare ◽  
Virulence Genes ◽  
Recessive Gene ◽  
Breeding Program ◽  
Hordeum Vulgare L ◽  
Barley Cultivars ◽  
Ustilago Hordei

Virulence of Ustilago hordei (Pers.) Lagerh. and U. nigra Tapke on the barley (Hordeum vulgare L.) cultivars Keystone and Conquest was studied. One recessive gene or linked genes, the same in both smut species, appeared to confer virulence on both cultivars. Earlier investigators had found identical virulence genes in both species of smut for the cultivars Excelsior, Lion, Pannier and Trebi. Therefore, testing for resistance or susceptibility in a breeding program could be done with a strain of only one of the species.

scholarly journals The limits to artificial selection for body weight in the mouse: IV. Sources of new genetic variance—irradiation and outcrossing

1967 ◽  
Vol 9 (1) ◽  
pp. 87-98 ◽  
Author(s):  
R. C. Roberts
Keyword(s):  
Body Weight ◽  
Artificial Selection ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Negative Results ◽  
Selection For ◽  
The Cross

1. Two methods are examined of introducing new genetic variance into a line of mice selected for high 6-week weight which, at its limit, displayed no additive genetic variance.2. The first method—irradiation—gave largely negative results. Any further gain under selection that was achieved could not be clearly distinguished from a possible environmental trend.3. The second method—outcrossing to an unselected strain and then selecting from the cross—resulted in a clear gain over the original limit, but nine generations were required even to recover the original limit.4. Various methods of transcending selection limits are evaluated in terms of their application to livestock improvement.

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