Breeding and Quantitative Genetics

Rumbaugh, M. D.; Caddel, J. L.; Rowe, D. E.

doi:10.2134/agronmonogr29.c25

Cited by 31 publications

(23 citation statements)

References 62 publications

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“…The number of parents selected for the syn 0 generation (i.e., original parents of a synthetic) is a vital consideration for alfalfa breeders. Syn 0 parent numbers determine inbreeding amounts in future synthetic generations, and associated severe inbreeding depression (Busbice, 1969; Busbice & Wilsie, 1966; Rumbaugh, Caddel, & Rowe, 1988). So‐called narrow‐based synthetics have a few parents while so‐called broad‐based synthetics have around 100 parents (Rumbaugh et al., 1988).…”

Section: Introductionmentioning

confidence: 99%

“…Syn 0 parent numbers determine inbreeding amounts in future synthetic generations, and associated severe inbreeding depression (Busbice, 1969; Busbice & Wilsie, 1966; Rumbaugh, Caddel, & Rowe, 1988). So‐called narrow‐based synthetics have a few parents while so‐called broad‐based synthetics have around 100 parents (Rumbaugh et al., 1988). A study of the Association of Official Seed Certifying Agency (AOSCA) alfalfa variety registrations from 2008 to 2015 shows a clear bimodal distribution for syn 0 parent number, with one group having an average of 14 syn 0 parents (i.e., narrow‐based), and the other group having an average of 105 syn 0 parents (i.e., broad‐based) (Riday, Johnson, Engh, & Darling, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Synthetic cultivar parent number impacts on genetic drift and disease resistance in alfalfa

Steinmetz

Huset²,

Rouse

et al. 2020

Crop Science

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Alfalfa (Medicago sativa L.) varieties are generally bred as synthetics. The number of selected parents to create a variety is important during breeding, as alfalfa suffers from severe inbreeding depression. In this study, we tested if there was more genetic drift in synthetic populations with fewer parents (i.e., narrow‐based synthetics) as measured by two parameters: a loss of allelic richness and changes in disease resistance. Out of five base germplasms, parents were selected based on plant field vigor to create derived narrow‐based (six‐parent) and broad‐based (56‐ to 86‐parent) synthetics in order to test the new synthetics compared with their base populations for resistance to four diseases: anthracnose, Phytophthora root rot (PRR), Aphanomyces root rot (ARR), and Fusarium wilt (FW). Using simple sequence repeat (SSR) DNA markers, we also calculated allele frequency changes and allele richness for the original populations and the selected parents of the derived synthetics. Based on the DNA markers, we saw strong evidence of greater genetic drift in the narrow‐based selections compared with the broad‐based selections. The narrow selections had greater allele frequency changes and had fewer (11.5–33.9% fewer) alleles compared with the broad selections and original populations. There was only moderate evidence of genetic drift affecting disease resistance. Within some populations, parent number had an effect on anthracnose and FW resistance, but not PRR or ARR resistance. We suspect that because disease resistance is a complex, often multigenic trait in alfalfa, disease resistance is less influenced by genetic drift, particularly compared with neutral DNA markers.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthetic cultivar parent number impacts on genetic drift and disease resistance in alfalfa

Steinmetz

Huset²,

Rouse

et al. 2020

Crop Science

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“…Genetic improvement of the population cannot be achieved beyond the boundaries that are determined by genes. Therefore, the selection of germplasm that will be included in the breeding is a very sensitive stage of breeding process (Rumbaugh et al, 1988). In order to achieve the expected progress, sources of parental germplasm, population size and intensity of selection are very important.…”

Section: Introductionmentioning

confidence: 99%

Morphometric characteristics of Lotus corniculatus L. genotypes

Radic¹,

Saric²

2013

Afr. J. Biotechnol.

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The aim of this study was to examine the degree of variability in morphological and agronomic characteristics of 20 Lotus corniculatus L. local genotypes, and also to set aside germplasm that will be used as a source of genetic basis for improvement of the studied properties. In poor quality soils, L. corniculatus L. plays an important role providing protein component in animal feeds. The importance of L. corniculatus L. in livestock development at hilly-mountainous areas is enormous. This study presents productive characteristics of 20 L. corniculatus L. genotypes selected from local populations in the previous period of selection. Significant differences were observed for most of the monitored parameters. The studied genotypes showed the greatest variability in green matter yield (CV 49, 58), number of pods per plant (CV 26, 27) and seed yield (CV 34, 31). To determine the significance of differences between the genotypes and their ranking for the level of significance, Duncan's multiple range test was used. Based on the results of Duncan's multiple range test and analysis of the significance of differences between genotypes, it was ascertained that genotypes G1, G3, G15 and G17 are the basis for the creation of synthetic variety with good production properties.

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“…An 11 to 50% selfing rate has been observed in insect-mediated alfalfa pollination (Riday et al, 2015). Traditionally, alfalfa breeders inter-mate groups of parental genotypes in a polycross to obtain either bulk seed or maternal halfsib seed from these parental genotypes (Rumbaugh et al, 1988). One common alfalfa breeding technique utilizes such polycross seed to establish space-plant transplanted nurseries (Rumbaugh et al, 1988).…”

mentioning

confidence: 99%

“…Traditionally, alfalfa breeders inter-mate groups of parental genotypes in a polycross to obtain either bulk seed or maternal halfsib seed from these parental genotypes (Rumbaugh et al, 1988). One common alfalfa breeding technique utilizes such polycross seed to establish space-plant transplanted nurseries (Rumbaugh et al, 1988). Individual plants are evaluated for a period of time, after which a proportion of nursery plants are selected and combined in a new polycross to complete the selection cycle.…”

mentioning

confidence: 99%

Measuring the Inefficiency of Allowing Self‐Pollinated Alfalfa Progeny into Breeding Nurseries

Riday

Johnson²,

Engh³

et al. 2017

Crop Science

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Although alfalfa (Medicago sativa L.) is considered an outcrossing species, the self‐pollination incidence during insect pollination can be substantial, with an observed 30% average selfing rate. Despite this, alfalfa breeders utilizing space‐plant evaluation nurseries make no attempt to discriminate self‐pollination‐derived progeny (selfs) from outcross progeny. Due to alfalfa's substantial inbreeding depression, the selfed individuals have much lower breeder utility. This study examines an alfalfa space‐plant breeding nursery in which selfed and outcross progeny had been identified using DNA markers for the following phenotypic traits: plant vigor, fall height, fall dormancy, first and second winter survival, plant lodging, and profusion of flowering. Trait means, phenotypic and additive variances, and narrow‐sense heritabilities on a halfsib mean basis were determined for selfed and outcross progeny. For most traits, inbreeding depression was severe, with approximately 80% reductions in performance. Selfed progeny for most traits had reduced phenotypic variances compared with outcross progeny. No differences in estimated additive variance and heritabilities were observed between the two types of progeny. Assuming a 30% selfing rate and a selection intensity less than or equal to 10%, we would expect to select few if any selfed progeny from a space‐plant nursery that had plant vigor phenotypic distributions observed in this study. The estimated maximum loss in genetic gain due to the presence of selfed progeny in breeding nurseries for selection intensities from 1 to 10% was estimated at a 10% genetic gain reduction. We conclude that selfed progeny in breeding nurseries are a hindrance, and if possible, they should be minimized or eliminated.

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Breeding and Quantitative Genetics

Cited by 31 publications

References 62 publications

Synthetic cultivar parent number impacts on genetic drift and disease resistance in alfalfa

Synthetic cultivar parent number impacts on genetic drift and disease resistance in alfalfa

Morphometric characteristics of Lotus corniculatus L. genotypes

Measuring the Inefficiency of Allowing Self‐Pollinated Alfalfa Progeny into Breeding Nurseries

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