Genetic diversity of the `peruvianum-complex' (Lycopersicon peruvianum (L.) Mill. and L. chilense Dun.) revealed by RAPD analysis |
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| Authors: | Hiroaki Egashira Hiroyuki Ishihara Tadashi Takashina Shigeru Imanishi |
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| Institution: | (1) Quality Wheat CRC Ltd, Locked Bag No 1345, P.O, North Ryde, NSW, 2113;(2) Plant Breeding Institute, The University of Sydney, Woolley Bldg A20, NSW, 2006, Australia |
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| Abstract: | Two lines of hexaploid wheat were crossed and the basic generations of parent, F1, F2 and back-cross were sown in a controlled-environment
chamber. FreshF1 and back-cross grains were generated, so the material could be handled either as the standard set of basic
generations on a whole-plant basis, or as an extended set on an embryo or endosperm basis. The experiment was repeated. Mature
grains were harvested and the starch particle size distribution was analysed in 3284 grains from 111 plants. Means and variances
were partitioned into additive, dominance and interaction components. Grains from cross-pollinations had B-granule contents
between parental values, rather than of the maternal parent, indicating an involvement of the grain genotype. Quantitative
models based on endosperm genotype gave a better fit to the data than those based on embryo genotype. The difference in starch
B-granule content between the parents was largely due to additive genes. Dominant genes were also indicated, with the first
dose in the triploid endosperm having a large effect while the second dose had little or none. Non-allelic interactions were
significant in the second experiment where the use of more types of backcross made them more detectable. There were also small
and significant residual effects of the maternal plant in the first experiment, attributed to the vigour of the F1 mother
plant and to the cytoplasm of Sunco. Narrow-sense heritability was low, between 0.05and 0.18 depending on the generation.
Transgressive segregation was not found, suggesting that all alleles tending to increase the B-granule content were found
in the Sunco parent and none in ME71. There was also no detectable heterosis in this character. The results show that breeding
and selection for a low B-granule content should be possible but a further reduction will require new and complementary genes.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | A granules B granules quantitative analysis starch quality triploid endosperm Triticum aestivum |
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