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Biochemical genetics of pigmentation in pisum


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Statham, Carmel M 1975 , 'Biochemical genetics of pigmentation in pisum', PhD thesis, University of Tasmania.

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The biochemical genetics of flavonoid pigmentation has been
investigated for many species and genera over a long period. In the
case of the genus Pisum, a great many genetical studies have been
carried out, but very little biochemistry has been undertaken. The
present investigation was designed to use the large amount of genetical
material available as a basis for an investigation of the biochemistry
of pigmentation in Pisum.
Six loci were known to affect flower colour in Pisum, these being
A, Am, Ar, B, Ce and Cr, and a pair of complementary loci, PUr and Pu
had been shown to be responsible for the anthocyanin colouration of pod
tissue. No specific information was available as to the mode of action
of these loci in the biosynthesis of flavonoids in Pisum, and also there
were no reports of the interaction of the flower colour loci with the
loci responsible for the flavonoid pigmentation in vegetative tissues.
The results presented in this thesis outline the mode of action of
the six loci, A, Am, Ar, B, Ce and Cr, in the production of the range
of flower colours found in the genus Pisum. Three of these loci, A,
B and GP, have a direct qualitative effect on the nature of the floral
anthocyanins, A being responsible for the production of all classes of
flavonoid in the flowers and for the production of anthocyanins in pod
and leaf axil tissue; the B gene is responsible for the 5 1 -hydroxylation of anthocyanins in the flowers, pods and leaf axils, while the Cr gene was found to be responsible for the 3' - and 5' -methylation of floral
anthocyanins and for the determination of rhamnose as the glycosyl
substituent at position 3 of such anthocyanins. Further investigations
showed that the biochemical effect of the Cr gene is confined to floral
tissues, and is not evident in the vegetative tissues such as pods and
The other three loci which were known to affect flower colour in
Pisum, Am, Ar and Ce, were shown to have quantitative effects on
floral anthocyanins, the precise complement being determined by the
genotypic constitution with respect to the previously mentioned loci,
A, B and Cr, The three quantitative flower colour loci have varying
effects in vegetative tissue, which is described in the text. No
definite conclusions as to the mode of action of the quantitative loci
were reached, but the results obtained suggested that the loci, Ar and
Ce, may have their effects by modifying the action of one of the qualitative
loci, Cr.
During the investigation, a new gene, Cgf, was described, C-glycosyl
flavones being present in the standard petals of Pisum in the presence
of the dominant allele. Several new combinations of this gene with the
previously described flower colour genes were obtained from the crossing
programme undertaken, and the chemical screening of these new genotypes
showed the dominant Cgf gene to be hypostatic to the recessive a gene.
The structure of the standard petal flavones was found to be the same
for all genotypes investigated, and the qualitative flower colour loci
do not affect the chemical structure of the floral flavones.

Item Type: Thesis - PhD
Authors/Creators:Statham, Carmel M
Keywords: Legumes
Copyright Holders: The Author
Copyright Information:

Copyright the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s). 1974.

Additional Information:

Bibliography: l. 130-138. Thesis (Ph.D.) University of Tasmania, 1974/5

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