scholarly journals DISTRIBUTION OF NONSTRUCTURAL VARIATION ALONG THREE CHROMOSOME ARMS BETWEEN WHEAT CULTIVARS CHINESE SPRING AND CHEYENNE

Genetics ◽  
1984 ◽  
Vol 106 (2) ◽  
pp. 309-324
Author(s):  
Anne Crossway ◽  
Jan Dvořák
Keyword(s):  
Chinese Spring ◽  
Continuous Distribution ◽  
Inbred Lines ◽  
Wheat Cultivars ◽  
Chromosome Variation ◽  
Homologous Chromosomes ◽  
Ring Bivalents ◽  
Chromosome Arm ◽  
Parental Inbred ◽  
The Mean

ABSTRACT Metaphase I (MI) pairing of wheat homologous chromosomes is usually reduced in hybrids between cultivars relative to the parental inbred lines. Previous work suggested that this phenomenon is caused by polymorphism in nucleotide sequences (nonstructural chromosome variation) among wheat cultivars. The present work investigated the distribution of this variation along three selected chromosome arms between cultivars Chinese Spring and Cheyenne. Chinese Spring ditelosomics 3Aq, 6Ap and 6Bp were crossed with disomic substitutions of Cheyenne chromosomes 3A, 6A and 6B in Chinese Spring, respectively. The resulting F1 plants, called substituted monotelodisomics, were crossed with the respective Chinese Spring monosomics, producing potentially "recombinant" substituted monosomics. When these "recombinant" chromosomes were combined with the parental Chinese Spring telosomes, marked reductions in mean telosome-pairing frequency were found compared with the corresponding Chinese Spring monotelodisomics. The mean pairing frequencies of the "recombinant" chromosomes showed a continuous distribution between those of the substituted and Chinese Spring monotelodisomics. The results suggest that the nonstructural variation that reduces MI pairing between chromosomes of different wheat cultivars is not localized in a specific site but distributed along each chromosome arm. Little variation was found among monotelodisomics for either the number of ring bivalents per cell or the number of univalents other than those constituting the heteromorphic pair. This implies that the reductions in MI pairing between the Cheyenne and Chinese Spring chromosomes are caused by something residing within these specific chromosomes that does not affect the pairing of the remaining Chinese Spring chromosomes in the same cell. Furthermore, the absence of parental types among the "recombinant"-substituted monotelodisomics suggests that the sequences involved in the variation studied here are capable of converting heterohomologous chromosomes to something intermediate in nature in the span of only a single generation.

Yields of mixtures of single-cross hybrid field beans (Viciafaba L.) with one of the parental inbred lines

1966 ◽  
Vol 67 (2) ◽  
pp. 235-237 ◽  
Author(s):  
D. A. Bond ◽  
J. L. Fyfe ◽  
Gillian Toynbee-Clarke
Keyword(s):  
Inbred Lines ◽  
The Other ◽  
Normal Rate ◽  
Single Cross ◽  
Parental Inbred ◽  
The Mean ◽  
Field Beans

The yields of seed from a hybrid, one of its parents and different mixtures of the hybrid and parent were compared in the case of two different hybrids. Open-pollinated controls were included in the trial, which was sown at about the normal rate for beans. With both hybrids a mixture of 11 of hybrid to 1 of parent yielded as well as the hybrid itself and mixtures of 2 of hybrid to 1 of parent yielded in both cases about 7 cwt./acro more than the mean of the open-pollinated controls. With the higher-yielding hybrid, which had less contrast in vegetative vigour between hybrid and parent, mixtures in the proportions 5:1 and 2:1 showed declining yields, but with the other hybrid they yielded as well as the pure hybrid.

The synaptic behaviour of the wild forms of Triticum turgidum and T. timopheevii

Genome ◽  
2001 ◽  
Vol 44 (4) ◽  
pp. 517-522 ◽  
Author(s):  
M Martínez ◽  
T Naranjo ◽  
C Cuadrado ◽  
C Romero
Keyword(s):  
Synaptonemal Complex ◽  
Triticum Turgidum ◽  
Genetic System ◽  
Wild Wheat ◽  
Homologous Chromosomes ◽  
Tetraploid Wheats ◽  
Ring Bivalents ◽  
In The Wild ◽  
The Mean ◽  
Wild Accessions

Different wild allopolyploid species of Triticeae show extensive bivalent formation at zygotene while a considerable number of multivalents is present in cultivated polyploid wheats. To study the chromosome behaviour at early meiotic stages in wild forms of tetraploid wheats Triticum turgidum and T. timopheevii (2n = 4x = 28) we have analysed the synaptic pattern in fully traced spread nuclei at mid- and late zygotene and at pachytene of wild accessions of these species. The mean number of synaptonemal complex (SC) bivalents at mid-zygotene ranged from 12.22 to 13.14 among the accessions studied indicating a strong restriction of synapsis initiation to homologous chromosomes. The mean of bivalents increased at pachytene because of the transformation of multivalents into bivalents. Ring bivalents observed at metaphase I support that SC bivalents were formed by homologous chromosomes. The average values of SC bivalents at mid-zygotene in the wild forms are much higher than the average values observed in the cultivated tetraploid wheats but similar to that of a mutant line of T. turgidum with a duplication that includes Ph1, the major homoeologous pairing suppressor locus. These results suggest that the efficiency of the mechanism operating in the homologous recognition for synapsis is higher in wild wheat populations than in cultivated varieties. Apparently, a relatively detrimental modification of the pairing regulating genetic system accompanied the domestication of the wild wheat forms.Key words: Ph1 locus, Triticum turgidum, Triticum timopheevii, synaptonemal complex, diploidisation.

scholarly journals DISTRIBUTION OF NONSTRUCTURAL VARIATION BETWEEN WHEAT CULTIVARS ALONG CHROMOSOME ARM 6Bp: EVIDENCE FROM THE LINKAGE MAP AND PHYSICAL MAP OF THE ARM

Genetics ◽  
1984 ◽  
Vol 106 (2) ◽  
pp. 325-333
Author(s):  
Jan Dvořák ◽  
Kuey-Chu Chen
Keyword(s):  
Linkage Map ◽  
Chinese Spring ◽  
Physical Map ◽  
Rrna Genes ◽  
Gene Region ◽  
Rrna Gene ◽  
Crossing Over ◽  
Wheat Cultivars ◽  
Chromosome Arm ◽  
26S Rrna

ABSTRACT Metaphase I (MI) pairing of homologous chromosomes in wheat intercultivar hybrids (heterohomologous chromosomes) is usually reduced relative to that within the inbred parental cultivars (euhomologous chromosomes). It was proposed elsewhere that this phenomenon is caused by polymorphism in nucleotide sequences (nonstructural chromosome variation) among wheat cultivars. The distribution of this polymorphism along chromosome arm 6Bp (=6BS) of cultivars Chinese Spring and Cheyenne was investigated. A population of potentially recombinant chromosomes derived from crossing over between telosome 6Bp of Chinese Spring and Cheyenne chromosome 6B was developed in the isogenic background of Chinese Spring. The approximate length of the Chinese Spring segment present in each of these chromosomes was assessed by determining for each chromosome the interval in which crossing over occurred (utilizing the rRNA gene region, a distal C-band and the gliadin gene region as markers). The MI pairing frequencies of these chromosomes (only the complete chromosomes were used) with the normal Chinese Spring telosome 6Bp were determined. These were directly proportional to the length of the euhomologous segment. The longer the incorporated euhomologous segment the better was the MI pairing. This provided evidence that the heterohomologous chromosomes are differentiated from each other in numerous sites distributed throughout the arm.—The comparison of the physical map of arm 6Bp with the linkage map showed a remarkable distortion of the linkage map; no crossing over was detected in the proximal 68% of the arm. A population of 49 recombinant chromosomes was assayed for recombination within the rRNA gene region, but none was detected. No new length variants of the nontranscribed spacer separating the 18S and 26S rRNA genes were detected either.

scholarly journals A novel approach for nitrogen diagnosis of wheat canopies digital images by mobile phones based on histogram

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xin Qi ◽  
Yanan Zhao ◽  
Yufang Huang ◽  
Yang Wang ◽  
Wei Qin ◽  
...  
Keyword(s):  
Neural Network ◽  
Mobile Phones ◽  
Mean Value ◽  
Wheat Cultivars ◽  
N Content ◽  
Color Parameters ◽  
The Neural Network ◽  
The Mean ◽  
Leaf N Content ◽  
Leaf N

AbstractThe accurate and nondestructive assessment of leaf nitrogen (N) is very important for N management in winter wheat fields. Mobile phones are now being used as an additional N diagnostic tool. To overcome the drawbacks of traditional digital camera diagnostic methods, a histogram-based method was proposed and compared with the traditional methods. Here, the field N level of six different wheat cultivars was assessed to obtain canopy images, leaf N content, and yield. The stability and accuracy of the index histogram and index mean value of the canopy images in different wheat cultivars were compared based on their correlation with leaf N and yield, following which the best diagnosis and prediction model was selected using the neural network model. The results showed that N application significantly affected the leaf N content and yield of wheat, as well as the hue of the canopy images and plant coverage. Compared with the mean value of the canopy image color parameters, the histogram could reflect both the crop coverage and the overall color information. The histogram thus had a high linear correlation with leaf N content and yield and a relatively stable correlation across different growth stages. Peak b of the histogram changed with the increase in leaf N content during the reviving stage of wheat. The histogram of the canopy image color parameters had a good correlation with leaf N content and yield. Through the neural network training and estimation model, the root mean square error (RMSE) and the mean absolute percentage error (MAPE) of the estimated and measured values of leaf N content and yield were smaller for the index histogram (0.465, 9.65%, and 465.12, 5.5% respectively) than the index mean value of the canopy images (0.526, 12.53% and 593.52, 7.83% respectively), suggesting a good fit for the index histogram image color and robustness in estimating N content and yield. Hence, the use of the histogram model with a smartphone has great potential application in N diagnosis and prediction for wheat and other cereal crops.

Maize Stand Density Yield Response of Parental Inbred Lines and Derived Hybrids

Crop Science ◽  
2016 ◽  
Vol 57 (1) ◽  
pp. 32-39 ◽  
Author(s):  
Agustina Amelong ◽  
Fernando Hernández ◽  
A. Daniel Novoa ◽  
Lucas Borrás
Keyword(s):  
Stand Density ◽  
Inbred Lines ◽  
Yield Response ◽  
Parental Inbred

Varietal reactions of Trifolium subterraneum L. to Phaseolus virus 2 Pierce.

1954 ◽  
Vol 5 (4) ◽  
pp. 598 ◽  
Author(s):  
EM Hutton ◽  
JW Peak
Keyword(s):  
Trypan Blue ◽  
Continuous Distribution ◽  
Systemic Infection ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Epidermal Cells ◽  
Severe Strain ◽  
Resistant Varieties ◽  
Lethal Reaction ◽  
The Mean

A number of varieties of subterranean clover (Trifolium subterraneum L.) were tested with a severe strain of Phaseolus virus 2 Pierce. Northam First Early, Dwalganup, and Pink Flowered gave lethal necrotic reactions while the rest developed mottles and chlorosis of different degrees of intensity. Reductions in the mean fresh weights of plants of five subterranean clover varieties ranged from 26.1 to 76.7 per cent. Epidermal cells of mottled leaves contained irregular aggregates of viroplasts stained by treatment with phloxine-trypan blue. Viroplasts in young tip leaves did not stain if the plants were held at temperatures below 44.6°F while those in mature basal leaves were not so affected. The lethal-reactors Northam First Early, Dwalganup, and Pink Flowered were resistant in the field to Phaseolus virus 2. With hand inoculation in the glass-house an average of 10 per cent. of plants of these varieties remained free from systemic infection, whereas all the plants of mottle-reacting varieties became systemically infected. The virus had a discontinous distribution in plants of lethal-reactors, compared with a continuous distribution in those of mottle-reactors such as Mount Barker. The lethal reaction is heritable in a dominant fashion in most crosses, so that the development of desirable new virus- resistant varieties is possible.

scholarly journals Variability of leaf Cadmium content in tetraploid and hexaploid wheat

Genetika ◽  
2009 ◽  
Vol 41 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Marija Kraljevic-Balalic ◽  
Novica Mladenov ◽  
Igor Balalic ◽  
Miroslav Zoric
Keyword(s):  
Cadmium Concentration ◽  
Tetraploid Wheat ◽  
Anthropogenic Sources ◽  
Cadmium Content ◽  
Atomic Absorption Spectrometer ◽  
Wheat Cultivars ◽  
Mean Values ◽  
The Mean ◽  
Heading Stage ◽  
Absorption Spectrometer

Cadmium (Cd) is a toxic trace metal pollutant for humans, animals, and plants. It is a heavy metal present in soils from natural and anthropogenic sources. Much of the Cd taken up by plants is retained in the root, but a portion is translocated to the aerial portions of the plant and into the seed. The objective of this research was to determine the variability and diversity of Cd content in the leaves of 30 wheat cultivars with different ploidy level, during two years. Analyses of Cd content (ppm) in the leaves at heading stage were performed with an atomic absorption spectrometer (AAS). Significant differences between the mean values of the genotypes in Cd content were found. Tetraploid wheat genotypes had higher Cd content than hexaploid genotypes. Cd content was predominantly influenced by the year of growing (73%). The influence of genotype on Cd content amounted 16% and the interaction genotype ? year 11%. The cluster of the genotypes consists of four groups. In the groups three and four were some of the genotypes (Kalyan Sona, Partizanka and NS Rana 5) with lowest Cd content in the leaves. They could be chosen as parents in the hybridization for lower cadmium concentration.

scholarly journals IDENTITY COEFFICIENTS IN FINITE POPULATIONS. I. EVOLUTION OF IDENTITY COEFFICIENTS IN A RANDOM MATING DIPLOID DIOECIOUS POPULATION

Genetics ◽  
1977 ◽  
Vol 86 (3) ◽  
pp. 697-713
Author(s):  
C Chevalet ◽  
M Gillois ◽  
R F Nassar
Keyword(s):  
Genetic Variability ◽  
Population Size ◽  
Effective Population Size ◽  
Random Mating ◽  
Matrix Multiplication ◽  
Inbred Lines ◽  
Inbreeding Coefficient ◽  
Effective Population ◽  
The Mean ◽  
Over Time

ABSTRACT Properties of identity relation between genes are discussed, and a derivation of recurrent equations of identity coefficients in a random mating, diploid dioecious population is presented. Computations are run by repeated matrix multiplication. Results show that for effective population size (Ne) larger than 16 and no mutation, a given identity coefficient at any time t can be expressed approximately as a function of (1—f), (1—f)3 and (1—f)6, where f is the mean inbreeding coefficient at time t. Tables are presented, for small Ne values and extreme sex ratios, showing the pattern of change in the identity coefficients over time. The pattern of evolution of identity coefficients is also presented and discussed with respect to N eu, where u is the mutation rate. Applications of these results to the evolution of genetic variability within and between inbred lines are discussed.

Establishment of the Wake Behind a Disk

1964 ◽  
Vol 86 (4) ◽  
pp. 869-880 ◽  
Author(s):  
Thomas Carmody
Keyword(s):  
Shear Stress ◽  
Ambient Pressure ◽  
Continuous Distribution ◽  
Flow Characteristics ◽  
Graphical Form ◽  
Stress Distributions ◽  
Mean Velocity ◽  
Pressure Distributions ◽  
Energy Relationships ◽  
The Mean

An air-tunnel study of the establishment of the wake behind a disk at a Reynolds number of approximately 7 × 104 was undertaken. On the basis of the measured data, such a wake is fully established, that is, similarity profiles of the flow characteristics are formed, within 15 diameters of the disk, and approximately 95 percent of the transfer of energy from the mean motion to the turbulence motion takes place within 3 diameters of the disk, in the region of the mean standing eddy. The measured mean ambient-pressure and mean total-pressure distributions, mean velocity distributions, turbulence-intensity and shear-stress distributions, and the mean streamline pattern are presented in graphical form, as are the quantitative balances of the integrated momentum and mean-energy relationships. A stream function consisting of a continuous distribution of doublets is introduced to extend the radial limit of understanding of the flow characteristics to a very large if not infinite radius. Considerable attention is given to the problem of obtaining and interpreting turbulence shear-stress data immediately downstream from the point of flow separation. The applicability of a local diffusion coefficient or virtual viscosity of the Boussinesq or Prandtl type for relating the turbulence shear stress to the radial gradient of mean axial velocity is discussed. The Bernoulli sum and the energy changes along individual streamlines investigated in an associated study are incorporated herein to obtain a quantitative estimate of the local errors involved in the turbulence-shear-stress measurements.

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