Inbreeding and Heterosis in Autotetraploid Alfalfa. I. Fertility

Dessureaux, L.; Galláis, A.

doi:10.1139/g69-083

Cited by 16 publications

(4 citation statements)

References 5 publications

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“…Wilsie (1958) showed that one generation of selfing resulted in a mean loss of 20 to 30% in vegetative vigor and 80 to 90% in self‐fertility. Dessureaux and Gallais (1969) investigated the pattern of inbreeding depression in two specific alfalfa genotypes and the impact on the first‐generation hybrid as the parents became more inbred. Inbreeding depression increased in each generation, and by the third generation, the progeny had practically become self‐sterile.…”

Section: Resultsmentioning

confidence: 99%

Identification of Founding Accessions and Patterns of Relatedness and Inbreeding Derived from Historical Pedigree Data in a White Clover Germplasm Collection in New Zealand

et al. 2019

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Pedigrees provide suitable input for tracking breeding crosses and monitor plants and animal populations. Pedigree analysis is an essential tool to visualize and describe population structure and genetic diversity. Pasture plant breeding relies on a range of strategies from closed system recurrent selection using elite cultivars to diversity‐focused programs using ecotypes and wild germplasm as parents. There is currently no published pedigree analysis of white clover (Trifolium repens L.), despite over a century of breeding efforts in New Zealand. A pedigree map was constructed for white clover germplasm stored in the Margot Forde Germplasm Centre located in Palmerston North, New Zealand. Inbreeding and kinship coefficients and the effective number of founders through time were estimated to assess genetic relatedness in the reference population. A total of 15,265 accessions were included in the map. The maximum number of traced generations was 15, and the mean completeness of parentage for the reference population was 72%. The mean number of offspring was 5.14. The origin of founding and introduced accessions was assessed. The effective number of founders was 175.68 or 17.5% of the total number of reference founders. Founding accessions and influencing ancestors were identified. One of the earliest parental accessions identified was ‘North Canterbury Type I’ from 1941. Relatedness was determined using the k coefficient, with k = 1 as complete relatedness. The overall mean relatedness was k = 0.002. Overall mean inbreeding level was 0.39%. Relatedness and inbreeding coefficients revealed distinct germplasm pools formed across time that are of interest to pre‐breeding efforts.

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Section: Resultsmentioning

confidence: 99%

Identification of Founding Accessions and Patterns of Relatedness and Inbreeding Derived from Historical Pedigree Data in a White Clover Germplasm Collection in New Zealand

et al. 2019

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“…performance of the F1 (3,4). Thus it is more difficult to capitalize on advantages of hybrid vigor in seed reproduced po1ysomics than it is in seed reproduced diploids, disomic po1yp1oids, or in asexually reproduced crops.…”

mentioning

confidence: 99%

Maximizing Heterozygosity in Autopolyploids

Bingham

1980

Polyploidy

124

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Polyploidy appears dependent on heterozygosity! The largest group of po1yp1oids, the a11opo1yp1oids (disomic po1yp1oids), have fixed heterozygosity in the two or more divergent genomes they possess (e.g., wheat, oats, cotton, tobacco, etc.). Hexaploid wheat, for example, although self-pollinated and basically homozygous at loci in each of its three genomes, has internal hybridity among loci with similar function in its three genomes. Disomic po1yp1oids thus are able to capitalize on the merits of both the se1f-and cross-fertilizing systems (1).The autopo1yp1oids (polysomic po1yp1oids) insure their heterozygosity through cross-pollination (e.g., alfalfa, birdsfoot trefoil, potato, and many grasses). We can find no example in crop plants of a successful polysomic polyploid species which is self-pollinated. Evidently the polysomic condition can not tolerate the homozygosity associated with self-pollination. The biochemical and physiological advantages of heterozygosity must be an important component of polyploid vigor (2). Polysomic po1yp1oids are represented by segregating and heterogeneous populations where maximum heterosis may be expressed by a few elite individuals in the population but not by the population per se. (Apomixis can preserve and perpetuate the elite polyploid individuals but will not be reviewed here.) In our seed reproduced polysomic po1yp1oids we can maximize the frequency of elite genotypes, but at present we cannot fix such genotypes in cultivated populations. As will be illustrated in this paper, maximum heterozygosity and heterosis does not occur in the Fl or single cross generation when parents are inbred (as it does 1n diploids or disomics) but occurs in the segregating double cross or an even later generation. Under polysomic polyploid conditions, the more inbred the parents, the lower the 471 W. H. Lewis (ed.), Polyploidy

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“…Depending on the original heterozygosity at a locus, inbreeding or the loss of heterozygosity will be affected differently. If a locus is duplex or simplex, the loss of allelic interactions at that locus will closely follow the inbreeding coefficient expectation and result in a linear response (Dessureaux & Gallais, 1969). However, if trigenic and tetragenic loci are involved, the loss of the three and four allele interactions will be more rapid than the F value predicts, resulting in a nonlinear response to inbreeding (Busbice & Wilsie, 1966).…”

Section: Parental Combining Ability and Inbreeding Depressionmentioning

confidence: 99%

Genetic characteristics of self fertility in highbush and half-high blueberries

1993

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Parents and ten progeny from each of ten controlled crosses, and thirteen progeny from G65 x 'Ashworth' were self and outcross pollinated to study the inheritance of self fertility and the associations between self fertility and zygotic inbreeding levels in highbush and half-high blueberry genotypes. Reductions in self fertility were apparently a response to increased inbreeding. Both percent fruit set and seeds per pollination were negatively associated with family zygotic inbreeding coefficients. Although inbreeding depression was responsible for much of the observed self fertility responses, an environmental component was apparent as well. A continuous distribution of self fertility levels among the G65 x 'Ashworth' progeny provided little evidence for simple inheritance of this trait. Estimates of heritability were not significant and some evidence of specific combining ability was detected, indicating that parental self fertility was not predictive of the self fertility of the progeny in this study. Variation for self fertility including high levels in some individuals indicates a potential level of self fertility which could be incorporated into future selections and cultivars.

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Inbreeding and Heterosis in Autotetraploid Alfalfa. I. Fertility

Cited by 16 publications

References 5 publications

Identification of Founding Accessions and Patterns of Relatedness and Inbreeding Derived from Historical Pedigree Data in a White Clover Germplasm Collection in New Zealand

Identification of Founding Accessions and Patterns of Relatedness and Inbreeding Derived from Historical Pedigree Data in a White Clover Germplasm Collection in New Zealand

Maximizing Heterozygosity in Autopolyploids

Genetic characteristics of self fertility in highbush and half-high blueberries

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