Breeding for improved nutritive value of Phalaris tuberosa herbage: an evaluation of alternative sources of genetic variation

1973 ◽  
Vol 24 (1) ◽  
pp. 21 ◽  
Author(s):  
RJ Clements
Keyword(s):  
Genetic Variation ◽  
Nitrogen Content ◽  
Nutritive Value ◽  
Negative Relationship ◽  
Heading Date ◽  
Breeding Program ◽  
Response To Selection ◽  
Annual Species ◽  
Selection For ◽  
Heading Stage

The variation in herbage nitrogen content and in vitro organic matter digestibility (IVDOM) among Phalaris species and hybrids, within an Algerian ecotype of P. tuherosa and among plants derived from a broadly based P. tuberosa breeding population, was examined. Variation was extensive in each of the three populations, and appears adequate for plant breeding purposes. In each population, IVDOM was negatively related to heading date. Another feature common to all populations at the heading stage was a negative relationship between WDOM and nitrogen content, demonstrable particularly when other factors having similar effects on both characters were held constant. In mature herbage of the P. tuberosa ecotype there was a positive genetic correlation between nitrogen content and IVDOM, but IVDOM at maturity was negatively related to nitrogen content at heading. Annual Phalaris species had higher average IVDOM values at heading (mean 70.5 %) than perennial species (mean 66.1 %) when data were adjusted to a common heading date. Although there was considerable intraspecific variation, only the annual species were sufficiently superior to the best P. tuberosa strains to warrant consideration for hybridizing with P. tuberosa. Since such hybrids have reduced perenniality, and are cytologically unstable, interspecific hybridization appears to have the least value as a source of herbage quality for a P. tuberosa breeding program. In addition, annual species were lower in nitrogen content (mean 1 .15 %) than perennials (mean 1.70 %) at a common heading date. Estimated heritabilities of IVDOM and nitrogen content of mature herbage of the P. tuberosa ecotype were 0.78 and 0.59 respectively, for a family mean based on replicated eight-plant rows. Genetic statistics indicated that a substantial response to selection for improved digestibility of mature herbage would be accompanied by a correlated increase in IVDOM at heading, a slight increase in nitrogen content at maturity, a decrease in nitrogen content at heading, little change in heading date, and perhaps some increase in the weight of individual tillers. Response to selection for increased nitrogen content would be small, and would be accompanied by a reduction in tiller weight. Individual plants derived from the broadly based population ranged from 56 to 76% IVDOM at the heading stage. This population, because of its agronomic superiority, is considered to be the most suitable source of genetic variation on which to base a breeding program.

scholarly journals Recurrent evolution of cross-resistance in response to selection for improved post-infection survival in Drosophila melanogaster

2021 ◽  
Author(s):  
Aparajita Singh ◽  
Aabeer Basu ◽  
Biswajit Shit ◽  
Tejashwini Hegde ◽  
Nitin Bansal ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Bacterial Pathogen ◽  
Host Population ◽  
Host Susceptibility ◽  
Cross Resistance ◽  
Response To Selection ◽  
Host Sex ◽  
Determining Factors ◽  
Selection For

The host susceptibility to one pathogen can decrease, increase, or remain unaffected by virtue of the host evolving resistance towards a second pathogen. Negative correlations between a host susceptibility to different pathogens is an often-cited explanation for maintenance of genetic variation in immune function determining traits in a host population. In this study, we investigated the change in susceptibility of Drosophila melanogaster flies to various novel bacterial pathogens after being experimentally selected for increased resistance to one particular bacterial pathogen. We independently selected flies to become more resistant towards Enterococcus faecalis and Pseudomonas entomophila, and baring a few exceptions the evolved populations exhibited cross-resistance against the range of pathogens tested in the study. Neither the identity of the native pathogen nor the host sex was major determining factors in predicting the pattern of cross-resistance exhibited by the selected populations. We therefore report that a generalized cross-resistance to novel pathogens can repeatedly evolve in response to selection for resistance against a single pathogen.

scholarly journals Genetic Variation and Selection for Carotene Content in Carrots

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 821E-821
Author(s):  
Philipp Simon
Keyword(s):  
Genetic Variation ◽  
Combining Ability ◽  
General Combining Ability ◽  
Mass Selection ◽  
Realized Heritability ◽  
Response To Selection ◽  
Carotene Content ◽  
Selection For ◽  
Variation And Selection ◽  
Made In

A six-parent diallel which included carrot inbreds with a range of carotene content from 80 to 490 ppm was evaluated over 2 years. General combining ability accounted for most of the variation observed. Phenotypic mass selection was exercised for high carotene content in three carrot populations. Response to selection continued to be high in one population, HCM, after 11 cycles of selection. In contrast, after three generations of selection, little progress was able to be made in a population derived from primarily Nantes-type open-pollinated cultivars. Realized heritability estimates varied from 15% to 49%. Environment contributed significantly to variation in carotene content.

scholarly journals Lessons from a GWAS study of a wheat pre-breeding program: pyramiding resistance alleles to Fusarium crown rot

2020 ◽  
Author(s):  
Marcos Malosetti ◽  
Laura B. Zwep ◽  
Kerrie Forrest ◽  
Fred A. van Eeuwijk ◽  
Mark Dieters
Keyword(s):  
Complex Traits ◽  
Selection Process ◽  
Breeding Program ◽  
Crown Rot ◽  
Response To Selection ◽  
Qtl Detection ◽  
Gwas Study ◽  
Fusarium Crown Rot ◽  
Breeding Populations ◽  
Selection For

AbstractMuch has been published on QTL detection for complex traits using bi-parental and multi-parental crosses (linkage analysis) or diversity panels (GWAS studies). While successful for detection, transferability of results to real applications has proven more difficult. Here, we combined a QTL detection approach using a pre-breeding populations which utilized intensive phenotypic selection for the target trait across multiple plant generations, combined with rapid generation turnover (i.e. “speed breeding”) to allow cycling of multiple plant generations each year. The reasoning is that QTL mapping information would complement the selection process by identifying the genome regions under selection within the relevant germplasm. Questions to answer were the location of the genomic regions determining response to selection and the origin of the favourable alleles within the pedigree. We used data from a pre-breeding program that aimed at pyramiding different resistance sources to Fusarium crown rot into elite (but susceptible) wheat backgrounds. The population resulted from a complex backcrossing scheme involving multiple resistance donors and multiple elite backgrounds, akin to a MAGIC population (985 genotypes in total, with founders, and two major offspring layers within the pedigree). A significant increase in the resistance level was observed (i.e. a positive response to selection) after the selection process, and 17 regions significantly associated with that response were identified using a GWAS approach. Those regions included known QTL as well as potentially novel regions contributing resistance to Fusarium crown rot. In addition, we were able to trace back the sources of the favourable alleles for each QTL. We demonstrate that QTL detection using breeding populations under selection for the target trait can identify QTL controlling the target trait and that the frequency of the favourable alleles was increased as a response to selection, thereby validating the QTL detected. This is a valuable opportunistic approach that can provide QTL information that is more easily transferred to breeding applications.

scholarly journals Gains through selection for grain yield in a winter wheat breeding program

2019 ◽  
Author(s):  
Dennis N. Lozada ◽  
Arron H. Carter
Keyword(s):  
Winter Wheat ◽  
Grain Yield ◽  
Wheat Breeding ◽  
Breeding Program ◽  
Response To Selection ◽  
Breeding Values ◽  
Wheat Breeding Program ◽  
Selection Strategies ◽  
Selection For ◽  
Estimated Breeding Values

AbstractIncreased genetic gains for complex traits in plant breeding programs can be achieved through different selection strategies. The objective of this study was to compare potential gains for grain yield in a winter wheat breeding program through estimating response to selection R values across several selection approaches including phenotypic (PS), marker-based (MS), genomic (GS), and a combination of PS and GS. Five populations of Washington State University (WSU) winter wheat breeding lines evaluated from 2015 to 2018 in Lind and Pullman, WA, USA were used in the study. Selection was conducted by selecting the top 20% of lines based on observed yield (PS strategy), genomic estimated breeding values (GS), presence of yield “enhancing” alleles of the most significant single nucleotide polymorphism (SNP) markers identified from genome-wide association mapping (MS), and high observed yield and estimated breeding values (PS+GS). Overall, PS compared to other individual strategies showed the highest response. However, when combined with GS, a 23% improvement in R for yield was observed, indicating that gains could be improved by complementing traditional PS with GS. Using GS alone as a selection strategy for grain yield should be taken with caution. MS was not that successful in terms of R relative to the other selection approaches. Altogether, we demonstrated that gains through increased response to selection for yield could be achieved in the WSU winter wheat breeding program by implementing different selection strategies either exclusively or in combination.

Selection for seed retention in Phalaris tuberosa L.

1963 ◽  
Vol 14 (6) ◽  
pp. 755 ◽  
Author(s):  
JR McWilliam
Keyword(s):  
Genetic Variation ◽  
Perennial Grass ◽  
Economic Problem ◽  
Base Population ◽  
Response To Selection ◽  
Seed Shattering ◽  
Commercial Strain ◽  
Seed Retention ◽  
Eastern Australia ◽  
Selection For

Loss of seed from the maturing inflorescence (seed shattering) is common in grasses and constitutes a serious economic problem in many species. This paper reports the results of artificial selection to improve seed retention in Phalaris tuberosa, an important perennial grass in south-eastern Australia. A study of the factors controlling the loss of seed in this species has revealed that the seed lies free within the inflorescence at maturity, and its loss is promoted by the opening of the glumes. This in turn is influenced by the structure of the inflorescence. The highest seed retention has been found in plants with a short rigid inflorescence containing a large number of densely packed spikelets. Wide variation for seed retention exists between strains of P. tuberosa. The lowest value (25%) was found for natural ecotypes from Algeria and Morocco, and the highest for a selection from a strain of the Australian commercial type obtained from Argentina (81%). An estimate of the heritability for seed retention was high (0.92 ± 0.11), and most of the genetic variation appeared to be additive. There was a marked response to selection for high seed retention. With the Argentine variety as the base population, an increase of 29% in the average level of seed retention was achieved from the first cycle of selection. This level represents an increase of 60% by comparison with the widely grown commercial strain. The importance of high seed retention in relation to the economics of Phalaris seed production is briefly discussed.

Predicted Evolutionary Response to Selection for Tolerance of Soybean (Glycine max) and Intraspecific Competition in a Nonweed Population of Poorjoe (Diodia teres)

Weed Science ◽  
1989 ◽  
Vol 37 (3) ◽  
pp. 451-457 ◽  
Author(s):  
Nicholas Jordan
Keyword(s):  
Multivariate Analysis ◽  
Genetic Variation ◽  
Intraspecific Competition ◽  
Path Coefficient ◽  
Experimental Population ◽  
Response To Selection ◽  
Weed Population ◽  
Evolutionary Response ◽  
Soybean Canopy ◽  
Selection For

Genetic variation within a nonweed (coastal) population of poorjoe was measured in an experimental population subjected to soybean and intraspecific competition for space and light. A sib analysis was used to estimate phenotypic and genetic variance/covariance components of aboveground biomass production and five independent measurements of growth defined by a path-coefficient model. A multivariate analysis of response to selection was applied to predict evolutionary change in the growth measurements in response to selection for performance under soybean and intraspecific space/light competition; sufficient genetic variation was present in the experimental population to allow a rapid response to this selection. Selection under competitive conditions was predicted to cause the nonweed population to emerge earlier, grow faster early in development, change in growth form, and grow faster under a soybean canopy. Most of these changes would increase the resemblance of the selected population to a weed population of poorjoe. However, the growth rate of the selected population under a soybean canopy was predicted to become greater than that actually observed in the present-day weed population. Multivariate analysis of response to selection may be generally useful in predicting evolutionary response of plant pest populations to control practices.

Comparing Genetic Variation within Red Winter Wheat Populations with and without Image-Based Optical Sorter Selection

2019 ◽  
Vol 9 (2) ◽  
pp. 266-277
Author(s):  
Hussein M. Khaeim ◽  
Anthony Clark ◽  
Tom Pearson ◽  
Dr. David Van Sanford
Keyword(s):  
Genetic Variation ◽  
Fusarium Head Blight ◽  
Heading Date ◽  
Fusarium Head Blight Resistance ◽  
Gibberella Zeae ◽  
Mass Selection ◽  
Head Blight ◽  
Red Winter Wheat ◽  
Two Populations ◽  
Head Scab

Head scab is historically a devastating disease affecting not just all classes of wheat but also barley and other small grains around the world. Fusarium head blight (FHB), or head scab, is caused most often by Fusarium graminearum (Schwabe), (sexual stage – Gibberella zeae) although several Fusarium spp. can cause the disease. This study was conducted to determine the effect of mass selection for FHB resistance using an image-based optical sorter. lines were derived from the C0 and C2 of two populations to compare genetic variation within populations with and without sorter selection. Our overall hypothesis is that sorting grain results in improved Fusarium head blight resistance. Both of the used wheat derived line populations have genetic variation, and population 1 has more than population 17. They are significantly different from each other for fusarium damged kernel (FDK), deoxynivalenol (DON), and other FHB traits. Although both populations are suitable to be grown for bulks, population 1 seems better since it has more genetic variation as well as lower FDK and DON, and earlier heading date. Lines within each population were significantly different and some lines in each population had significantly lower FDK and DON after selection using an optical sorter. Some lines had significant reduction in both FDK and DON, and some others had either FDK or DON reduction. Lines of population 1 that had significant reduction, were more numerous than in population 17, and FDK and DON reduction were greater.

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