Inbreeding in Synthetic Varieties<sup>1</sup>

Busbice, T. H.

doi:10.2135/cropsci1969.0011183x000900050026x

Cited by 62 publications

(47 citation statements)

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“…Effects on the mean. According to the theoretical results on the inbreeding and the structure of synthetic varieties at the tetraploid level (BUSBICE, 1969;DEMARLY, 1968;GALLAIS, 1968), the more inbred the parents the weaker the single crosses.…”

Section: Diallel Crossesmentioning

confidence: 99%

General and specific combining ability in lucerne at different levels of in breeding and performance of second-generation synthetics measured in competitive conditions

Rotili

Zannone

1974

Euphytica

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In a breeding program of luceme based on selfing in sward conditions general as well as specific combining ability was evaluated for diallel crosses made at different levels of inbreeding. The performance of the second generation synthetics was studied as well. The efficiency of selting and subsequent selection in improving the genetic value of parents is very important. The optimal solution for luceme breeding could well be the use of synthetic varieties which are based on 4 inbred clones.

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Section: Diallel Crossesmentioning

confidence: 99%

General and specific combining ability in lucerne at different levels of in breeding and performance of second-generation synthetics measured in competitive conditions

Rotili

Zannone

1974

Euphytica

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“…Our objectives were (a) to determine the effect of this selection on both self-and cross-fertility in succeeding generations, (b) Kempthorne (1957) and Busbice (1969). In these computations the parental clones were assumed to be noninbred (Fo:g;, unrelated showed that selection improved self-fertility Second, comparing populations 6 and 9, population t has a 57o superior seed set over that of population 6, even though population 9 was more inbred.…”

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confidence: 99%

Selection for Seed Set in Noninbred and Partly Inbred Populations of Alfalfa

Michaud¹,

Busbice²

1977

Can. J. Plant Sci.

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Mrculuo, R. lNo Bussrcn, T."H. 1977. Selection for seed set in noninbred and .partly inbred populations ofalfalfa. Alfalfa (Medicago sativa L) is a highly heterozygous cross-pollinating species, and most breeding efforts have been conducted on noninbred populations. The purpose of this study was to determine whether greater bieeding progress could be madi by selecting within partly inbred populations rather than within noninbred ones. One hundredandtwentyF (noninbred)

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“…Flowers contain both female (pistil) and male (stamen) structures and produce coiled seed pods bearing seeds with a weight of approximately 400 seeds per gram. Lucerne is allogamous, and subject to severe inbreeding depression (Busbice 1969). Lucerne is also known as alfalfa, and this name is used in the USA in particular.…”

Section: Lucerne Reproductive Biologymentioning

confidence: 99%

“…Irwin et al (2008) propose an improved breeding strategy which utilises recurrent selection, working at the individual genotype (plant). Production of new, synthetic cultivars would utilise few (4-8) elite S 0 genotypes with high general combining ability for yield (Busbice 1969;Irwin et al 2008) that have undergone phenotypic and/or molecular characterisation for the necessary pest and pathogen resistances in addition to target trait selection. The resultant cultivar, based on a few well characterised plants, will increase the chances of making genetic gain for target traits expected to demonstrate lower heritability.…”

Section: Implications Of Lucerne Genetics For Cultivar Developmentmentioning

confidence: 99%

“…For the reasons outlined in earlier sections (Chapter 2) lucerne cultivars usually consist of a population of genetically distinct individuals (Busbice 1969;Irwin et al 2001;Stanford 1951). Consequently, it is possible that the numerous distinct germplasm sources used in cultivar development (Brummer 1999) could separately provide loci, each displaying tetrasomic inheritance, contributing to P. medicaginis resistance in the cultivar.…”

Section: Many Target Traits Important For Medicago Sativa Cultivar Immentioning

confidence: 99%

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Development and validation of molecular markers for Phytophthora medicaginis resistance in lucerne

Armour¹

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Lucerne (Medicago sativa ssp. sativa L.) is one of the most important forage legumes worldwide, and Australia's most valuable perennial forage legume. Phytophthora root rot, caused by the oomycete pathogen Phytophthora medicaginis is a lethal disease of lucerne in Australia and America. The disease is a major productivity constraint when cultivars without adequate resistance levels are grown in conditions conducive to high disease pressure. The research presented here examined Phytophthora resistance in lucerne genotypes selected from Australian cultivars, however the findings are of relevance worldwide due to the extensive use of international (USA) germplasm in Australian lucerne breeding programs in particular.A broad-based synthetic approach, first described in1942, has been the most commonly used process in lucerne breeding. However, this approach presents an inherent set of limitations which are highlighted by the yield plateau observed in lucerne in the absence of disease and pest pressures.Improved breeding strategies have been proposed to address the limitations of the current approach and the constraints imposed by lucerne biology. These improved breeding strategies utilise synthetics based on far fewer parents than are currently being used, providing greater possibilities for making genetic gain for multiple quantitatively inherited traits.However, a paucity of information exists on the number, genomic location and diversity of P. medicaginis resistance loci available in the M. sativa gene pool for breeding Phytophthora resistant lucerne. This information would underpin selection of parental genotypes in narrow-based breeding schemes aimed at addressing the current yield stagnation in lucerne. One previous report described the mapping of Phytophthora resistance loci in the lucerne genotype W116, however the molecular marker systems employed did not enable chromosome number assignment to the linkage groups generated, and the markers have limited comparative mapping potential. The research presented here sought to address the current knowledge gap in the lucerne-Phytophthora pathosystem. It determined the genetic basis for P. medicaginis resistance in lucerne clone WA272 by assigning chromosome locations to the resistance loci identified and generated an alignment of the resistance loci identified with those in W116.An autotetraploid mapping population of 182 individuals was generated and phenotyped for P. medicaginis reaction using established inoculation procedures. The population was genotyped using SSR markers from existing M. sativa and M. truncatula genetic linkage maps. Large effect QTLs iii for resistance to P. medicaginis were detected in the WA272 x D mapping population, and using the linkage map developed, these were located to WA272 linkage groups 2, 5, 6 and 7. The large effect QTL identified on linkage groups 2 and 6 through interval mapping, and the best single markers from linkage groups 5 and 7 collectively explained 94%, 92% and 76% of the phenotypic variation for the cotyledon...

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Inbreeding in Synthetic Varieties¹

Cited by 62 publications

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General and specific combining ability in lucerne at different levels of in breeding and performance of second-generation synthetics measured in competitive conditions

General and specific combining ability in lucerne at different levels of in breeding and performance of second-generation synthetics measured in competitive conditions

Selection for Seed Set in Noninbred and Partly Inbred Populations of Alfalfa

Development and validation of molecular markers for Phytophthora medicaginis resistance in lucerne

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Inbreeding in Synthetic Varieties1

Cited by 62 publications

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General and specific combining ability in lucerne at different levels of in breeding and performance of second-generation synthetics measured in competitive conditions

General and specific combining ability in lucerne at different levels of in breeding and performance of second-generation synthetics measured in competitive conditions

Selection for Seed Set in Noninbred and Partly Inbred Populations of Alfalfa

Development and validation of molecular markers for Phytophthora medicaginis resistance in lucerne

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Inbreeding in Synthetic Varieties¹