Breeding and selection for high early season sugar content in a sugarcane (Saccharum spp. hybrids) improvement program

1994 ◽  
Vol 45 (7) ◽  
pp. 1569 ◽  
Author(s):  
MC Cox ◽  
DM Hogarth ◽  
PB Hansen
Keyword(s):  
Genetic Variance ◽  
Recurrent Selection ◽  
Sugar Content ◽  
Additive Genetic Variance ◽  
Breeding Population ◽  
Cane Sugar ◽  
Improvement Program ◽  
Narrow Sense Heritability ◽  
Saccharum Spp ◽  
Early Season

A recurrent selection program for high early season commercial cane sugar (CCS) in sugarcane (Saccharum spp. hybrids) commenced in 1988. About 20 families (first clonal stage) and their parents are grown in two regions each year. Elite clones with high early CCS are selected and these are recycled into the breeding population with a short generation interval. Estimates of narrow-sense heritability from midparent-offspring regressions were moderate to high (0.6 or greater). Thus breeding for this trait using a large database of information available on early CCS characteristics of parental clones should be effective. Additive genetic variance (=2A) was more important than non-additive genetic variance.

scholarly journals Selection strategies of segregant soybean populations for resistance to Asian rust

2009 ◽  
Vol 44 (11) ◽  
pp. 1452-1459 ◽  
Author(s):  
Aliny Simony Ribeiro ◽  
José Francisco Ferraz de Toledo ◽  
Magno Antonio Patto Ramalho
Keyword(s):  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Infected Leaf ◽  
Good Resistance ◽  
Narrow Sense Heritability ◽  
Growing Seasons ◽  
Selection Strategies ◽  
Line Selection ◽  
Soybean Resistance ◽  
Selection Of

The objective of this work was to identify the best selection strategies for the more promising parental combinations to obtain lines with good resistance to soybean Asian rust (Phakopsora pachyrhizi). Two experiments were carried out in the field during the 2006/2007 and 2007/2008 growing seasons, to determine the percentage of infected leaf area of individual plants of five parents and their segregant F2 and F3 populations. The data obtained indicates that additive genetic variance predominates in the control of soybean resistance to Asian rust, and that the year and time of assessment do not significantly influence the estimates of the genetic parameters obtained. The narrow-sense heritability (h²r) ranged from 23.12 to 55.83%, and indicates the possibility of successful selection of resistant individuals in the early generations of the breeding program. All the procedures used to select the most promising populations to generate superior inbred lines for resistance to P. pachyrhizi presented similar results and identified the BR01-18437 x BRS 232 population as the best for inbred line selection.

GENETIC VARIANCE OF PROTEOLYTIC ACTIVITY IN ALFALFA HERBAGE

1987 ◽  
Vol 67 (1) ◽  
pp. 159-165
Author(s):  
S. R. BOWLEY ◽  
B. D. McKERSIE
Keyword(s):  
Medicago Sativa ◽  
Proteolytic Activity ◽  
Genetic Variance ◽  
Effective Means ◽  
Breeding Population ◽  
Narrow Sense ◽  
Nonprotein Nitrogen ◽  
Narrow Sense Heritability ◽  
Medicago Sativa L

Protein hydrolysis can be extensive during ensiling of alfalfa (Medicago sativa L.) herbage. Such hydrolysis lengthens the ensiling phase and reduces the quality of the resultant feed. The objectives of this study were: (1) to estimate the genetic variance and narrow-sense heritability (via a half-sib analysis) of proteolytic activity in an alfalfa breeding population (OAC-A83); and (2) to estimate the genetic diversity among related Medicago subspecies (M. falcata, M. varia, M. praefalcata and M. glomerata), M. sativa introductions, and two cultivars, Iroquois and OAC Minto. An in vitro procedure was used to quantify proteolytic activity, which was expressed as milligrams of trichloroacetic acid (TCA)-soluble leucine equivalents per gram fresh leaf weight, released during a 7-d incubation. Significant (P < 0.05) differences were found among the half-sib families of OAC-A83. The narrow-sense heritability of proteolytic activity was low (13.9%). The expected response to selection for low proteolytic activity, if the top 10% of the plants were recombined, was 5% of the OAC-A83 population mean. Although significant (P < 0.05) differences were obtained among the Medicago introductions, none of the introductions or subspecies tested had lower proteolytic activity than that found in the two cultivars tested (Iroquois and OAC Minto). It was concluded that, although possible, genetic improvement of proteolytic potential in alfalfa may not be easily obtained. In the short term, rapid lowering of silage pH (e.g., bacterial inoculants or acid additives) will likely remain the most effective means of controlling protein degradation in alfalfa silage.Key words: Medicago sativa L., silage, ensiling, soluble nonprotein nitrogen, heritability, alfalfa

scholarly journals Genetic Control of O3 Sensitivity in a Cross Between Two Cultivars of Snap Bean

2000 ◽  
Vol 125 (2) ◽  
pp. 222-227 ◽  
Author(s):  
Richard A. Reinert ◽  
Gwen Eason
Keyword(s):  
Genetic Control ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Phenotypic Variance ◽  
Narrow Sense Heritability ◽  
Snap Bean ◽  
Reciprocal Crosses ◽  
Blue Lake ◽  
Environmental Component ◽  
Variance Estimates

Identification of genetic control of ozone (O3) sensitivity is desirable for selection of plant cultivars which are indicators of O3 stress. A cross was made between two cultivars of snap bean (Phaseolus vulgaris L.), `Oregon 91' (P1) and `Wade Bush' (P2), an O3-sensitive and O3-insensitive cultivar, respectively. Ten genetic populations (generations), `Oregon 91' (P1), `Wade Bush' (P2), F1, F2, backcrosses to both parents, and all reciprocal crosses, were field planted in each of two summers and evaluated for injury to O3. Ozone responses for the reciprocal crosses were not significantly different for any generation, so injury ratings from the reciprocal crosses were combined for each generation to provide six populations (P1, P2, F1, F2, BC1, and BC2) for analysis. When components of genetic variation were estimated from the six generations, additive genetic variance was the most important component in the total genetic variance available, although dominance variance was also a significant component. There was an inconsistency in the magnitude and the direction of the factors contributing to the dominance effects and also a large environmental component making up the phenotypic variance. Estimates of broad-sense heritability and narrow-sense heritability were 60% and 44%, respectively. Results suggest that O3-sensitive and O3-insensitive selections could be screened and evaluated in an ambient O3 environment. Several generations will be necessary, however, to develop `Bush Blue Lake' type selections that vary only in sensitivity to O3.

scholarly journals Narrow-sense heritability estimation of complex traits using identity-by-descent information

2017 ◽  
Author(s):  
Luke M. Evans ◽  
Rasool Tahmasbi ◽  
Matthew Jones ◽  
Scott I. Vrieze ◽  
Gonçalo R. Abecasis ◽  
...  
Keyword(s):  
Complex Traits ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Fundamental Parameter ◽  
Last Common Ancestor ◽  
Narrow Sense ◽  
Narrow Sense Heritability ◽  
Heritability Estimation ◽  
Causal Variants ◽  
Heritability Estimates

ABSTRACTHeritability is a fundamental parameter in genetics. Traditional estimates based on family or twin studies can be biased due to shared environmental or non-additive genetic variance. Alternatively, those based on genotyped or imputed variants typically underestimate narrow-sense heritability contributed by rare or otherwise poorly-tagged causal variants. Identical-by-descent (IBD) segments of the genome share all variants between pairs of chromosomes except new mutations that have arisen since the last common ancestor. Therefore, relating phenotypic similarity to degree of IBD sharing among classically unrelated individuals is an appealing approach to estimating the near full additive genetic variance while avoiding biases that can occur when modeling close relatives. We applied an IBD-based approach (GREML-IBD) to estimate heritability in unrelated individuals using phenotypic simulation with thousands of whole genome sequences across a range of stratification, polygenicity levels, and the minor allele frequencies of causal variants (CVs). IBD-based heritability estimates were unbiased when using unrelated individuals, even for traits with extremely rare CVs, but stratification led to strong biases in IBD-based heritability estimates with poor precision. We used data on two traits in ~120,000 people from the UK Biobank to demonstrate that, depending on the trait and possible confounding environmental effects, GREML-IBD can be applied successfully to very large genetic datasets to infer the contribution of very rare variants lost using other methods. However, we observed apparent biases in this real data that were not predicted from our simulation, suggesting that more work may be required to understand factors that influence IBD-based estimates.

scholarly journals Efficiencies of Clonally Replicated and Seedling Testing for Spruce Breeding and Deployment Strategies

2009 ◽  
Vol 58 (1-6) ◽  
pp. 292-300
Author(s):  
Y. H. Weng ◽  
Y. S. Park ◽  
D. Simpson ◽  
T. J. Mullin
Keyword(s):  
Genetic Variance ◽  
Gene Diversity ◽  
Additive Genetic Variance ◽  
Seed Orchard ◽  
Narrow Sense ◽  
Family Selection ◽  
Narrow Sense Heritability ◽  
Additive Variance ◽  
Clonal Seed Orchard ◽  
Seedling Test

AbstractGenetic gains based on a genetic test using clonal replicates were compared to those based on a test using seedlings at the same gene diversity and testing effort levels using POPSIM™ Simulator. Three testing and deployment strategies targeting for white spruce (P. glauca [Moench] Voss) and black spruce (P. mariana (Mill.) B.S.P.) in New Brunswick were compared: seedling test with clonal seed orchard deployed as seedlings (CSO_ST), clonally replicated test with clonal seed orchard deployed as seedlings (CSO_CRT), and clonally replicated test deployed as a clone mix (MVF). The breeding populations (BP) were formed by balanced within-family selection and the production populations (PP) were selected by strong restriction on relatedness, i.e., no parent in common. Compared to the seedling test, the clonally replicated test resulted in faster accumulation of additive effects but quicker loss of additive variance in the BP, and this is particular true in the case of lower narrow-sense heritability or less non-additive genetic variance. The quicker loss in BP additive variance was overcompensated for by its faster accumulation in BP additive effect, resulting in higher gain in the clonally replicated test based PPs. Compared to the CSO_ST, the gain superiority of the CSO_CRT increased with generations, decreasing narrow-sense heritability or reducing the amount of non-additive variance. Implementing MVF was the most effective in terms of gain in most simulated cases and its superiority over the CSO_ST increased with generations, decreasing narrowsense heritability, or increasing non-additive genetic variance. Overall results demonstrated significant advantages of using clonally replicated test both for BP advancement and PP selection in most of the scenarios, suggesting that clonally replicated test should be incorporated into current spruce breeding strategies.

scholarly journals Prediction of subgenome additive and interaction effects in allohexaploid wheat

2018 ◽  
Author(s):  
Nicholas Santantonio ◽  
Jean-Luc Jannink ◽  
Mark E. Sorrells
Keyword(s):  
Genomic Prediction ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Predictive Ability ◽  
Breeding Population ◽  
Wheat Breeding ◽  
Covariance Matrices ◽  
Genome Duplications ◽  
Increase In Accuracy ◽  
Allohexaploid Wheat

1AbstractWhole genome duplications have played an important role in the evolution of angiosperms. These events often occur through hybridization between closely related species, resulting in an allopolyploid with multiple subgenomes. With the availability of affordable genotyping and a reference genome to locate markers, breeders of allopolyploids now have the opportunity to manipulate subgenomes independently. This also presents a unique opportunity to investigate epistatic interactions between homeologous orthologs across subgenomes. We present a statistical framework for partitioning genetic variance to the subgenomes of an allopolyploid, predicting breeding values for each subgenome, and determining the importance of inter-genomic epistasis. We demonstrate using an allohexaploid wheat breeding population evaluated in Ithaca, NY and an important wheat dataset previously shown to demonstrate non-additive genetic variance. Subgenome covariance matrices were constructed and used to calculate subgenome interaction covariance matrices across subgenomes for variance component estimation and genomic prediction. We propose a method to extract population structure from all subgenomes at once before covariances are calculated to reduce collinearity between subgenome estimates. Variance parameter estimation was shown to be reliable for additive subgenome effects, but was less reliable for subgenome interaction components. Predictive ability was equivalent to current genomic prediction methods. Including only inter-genomic interactions resulted in the same increase in accuracy as modeling all pairwise marker interactions. Thus, we provide a new tool for breeders of allopolyploid crops to characterize the genetic architecture of existing populations, determine breeding goals, and develop new strategies for selection of additive effects and fixation of inter-genomic epistasis.

COMPARISON OF PREDICTED AND SIMULATED RESPONSES TO S1 SELECTION IN A DIPLOID, CROSS-FERTILIZED SPECIES

1981 ◽  
Vol 61 (1) ◽  
pp. 9-15 ◽  
Author(s):  
T. M. CHOO ◽  
L. W. KANNENBERG
Keyword(s):  
Coefficient Of Variation ◽  
Variance Component ◽  
Genetic Variance ◽  
Recurrent Selection ◽  
Genetic Models ◽  
Variance Component Analysis ◽  
Narrow Sense Heritability ◽  
Complete Dominance ◽  
Per Se ◽  
Good Agreement

Computer simulation was used to test the accuracy of mathematical formulae for predicting mean response and variance of response to S1 per se recurrent selection under both additive and complete dominance genetic models. S1 selection was simulated at two levels of selection intensity (5 and 25%) and two levels of narrow sense heritability (0.2 and 0.6) for 15 cycles. In each cycle, 400 S1 families were evaluated in simulated trials consisting of one replication of 10-plant plots at each of four locations. The character under selection was controlled by 40 independently assorted loci. For both genetic models, variance component analysis provided good estimates of genetic variance and the predicted gains were in good agreement with the simulated gains. The simulated coefficient of variation of response was small and was very close to the predicted coefficient of variation in each of the four selection regimes under both models.

Heritabilities and genetic and phenotypic correlations for height and diameter in coastal Douglas-fir

1982 ◽  
Vol 12 (2) ◽  
pp. 181-185 ◽  
Author(s):  
Francis C. Yeh ◽  
Chris Heaman
Keyword(s):  
Genetic Correlation ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Growing Season ◽  
Breeding Population ◽  
Douglas Fir ◽  
Single Tree ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates

Factorial crosses of 22 seed trees and 4 pollen parents from a breeding population of 445 coastal Douglas-firs were tested at two sites. Analyses of heights and diameters after the sixth growing season indicated only the significance of additive genetic variance. The single tree heritability estimates for height and diameter were 0.10 ± 0.07 and 0.12 ± 0.08, respectively. The genetic correlation between height and diameter was 0.81 ± 0.64.

GENETIC VARIANCES IN AN EIGHT PARENT HALF DIALLEL OF OATS

1976 ◽  
Vol 18 (3) ◽  
pp. 419-427 ◽  
Author(s):  
D. R. Sampson ◽  
I. Tarumoto
Keyword(s):  
Grain Yield ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Heading Date ◽  
Phenotypic Variance ◽  
Narrow Sense ◽  
Narrow Sense Heritability ◽  
Additive Component ◽  
Tests Of Fit ◽  
Half Diallel

Twenty-eight progenies with their eight parent cultivars of Avena saliva L. (2n = 6x = 42) were grown in F1, F2 and F3 in separate years; the F1 as spaced plants, the F2 and F3 as dense seeded populations. Additive genetic variance constituted most of the phenotypic variance of eight traits (heading date, plant height, stem diameter, grain yield and four components of yield) according to a Griffing Method 4, Model II analysis. Similarly, additive × year interactions were more important than nonadditive × year interactions. A Hayman-Jinks analysis of the same material but with the parents included showed that the additive component was 2 to 16 times larger than the dominance components in the F1 However in the F2 and F3 the dominance components became larger than the additive components for most traits instead of declining in importance as expected. Further, tests of fit to the hypotheses underlying the Hayman-Jinks analysis were negative in 8 of 24 cases. It is postulated that these discrepancies result from epistatic variance which caused an upward bias in the dominance estimates. The calculation and uses of two estimates of narrow-sense heritability are discussed.

scholarly journals Narrow-Sense Heritability of Selected Sensory Descriptors in Virginia-Type Peanut (Arachis hypogaea L.)1

2003 ◽  
Vol 30 (1) ◽  
pp. 64-66 ◽  
Author(s):  
T. G. Isleib ◽  
H. E. Pattee ◽  
F. G. Giesbrecht
Keyword(s):  
Arachis Hypogaea ◽  
Genetic Variance ◽  
Genetic Model ◽  
Additive Genetic Variance ◽  
Narrow Sense ◽  
Roasted Peanut ◽  
Narrow Sense Heritability ◽  
Breeding Lines ◽  
Arachis Hypogaea L ◽  
F2 Generation

Abstract The sweet, bitter and roasted peanut attributes of roasted peanut (Arachis hypogaea L.) flavor have been shown to be heritable traits. Previous research has estimated broad-sense heritability (H) and breeding values of numerous peanut cultivars and breeding lines for these attributes, but no study has estimated narrow-sense heritability (h2) in a specific population derived through hybridization and inbreeding. A population of 120 F3-derived families was developed without selection from the cross of NC 7/NC Ac 18431, a virginia-type line identified in 1990 as having a good flavor profile. The parents and F3:5 families were grown at two locations in North Carolina in 1995. SMK samples from each plot were roasted, ground to paste, tasted by a sensory panel, and scored for roasted peanut, sweet, bitter and astringent attributes. Additive and nonadditive genetic variances were estimated by equating variances among F2-derived families and among F3-derived families within F2-derived families to genetic covariances among inbred relatives. Regardless of whether the genetic model included dominance or additive-by-additive epistasis, the estimates of additive genetic variance for flavor attributes were small compared to those for nonadditive genetic variance. Narrow-sense heritability in the F2 generation was estimated at 0 for roasted peanut and astringent, 0.02 to 0.04 for sweet, and 0.01 to 0.03 for bitter, depending on the model used. Because of the low values of h2, which are specific to this population, gain from selection in early generations is expected to be limited within this population. Selection in this population should be practiced in late generations. Other parents have been identified whose crosses should produce greater improvement in sensory quality than can be expected from the NC 7 / NC Ac 18431 population.

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