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Title: Genetic studies of zonal pelargoniums
Author: Abdel Wahab, O. A. L.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1980
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Problems concerning the sorting-out and transmission of plastids in higher plants and studies leading to the present experiments are reviewed. Aspects of plastid inheritance in Pelargonium x Hortorum Bailey are investigated with six variegated cultivars containing mutant plastids in their gene cells, with six isogenic green clones derived from them, and with various derivatives. Characterization of the mutant plastids by their ability to synthesize chlorophyll, by the presence or absence of their ribosomes, and by their genetic stability, reveals two distinct plastid types, one stable and one unstable. The inheritance pattern of white plastids is determined by crossing the six variegated cultivars in all 36 possible ways; for each cross the frequency of restitution from white to green of the unstable plastid is used as a marker with which to estimate plastid transmission. An analysis of variance of these estimates shows that, in the competition between the two, the unstable plastid is superior to the stable and is comparable to a green plastid. Following G X W plastid crosses, there are two alternative segregation patterns of green, variegated and white embryos. Breeding evidence suggests that the two patterns are controlled by alternative genotypes of a nuclear gene (Pr). An extensive breeding programme between heterozygotes (Pr Pr ) and homozygotes (PrPr ), reveals a normal transmission of the Pr allele, when derived from the male parent, but a conditional transmission dependent upon M female type of plastid and the right male, when derived from the female parent. On inbreeding heterozygous plants, the progeny always segregate in a ratio of 1 homozygote (Pr Pr ) : 1 heterozygote (Pr Pr ) while the alternative homozygote (Pr Pr) is never found. It is suggested that there is an incompatibility mechanism in which the h-:1 alleles are self-compatible and the Pr2 alleles self-incompatible. General aspects of the genetics of chloroplasts and mitochondria are discussed in relation to the Pelargonium system.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available