Abstract
The inheritance of two quantitative characters is examined in the M2 and backcross generations derived from crosses of Nicotiana rustica that used pollen irradiated with 20 Krad of γ-rays. All generations examined show, on average, a reduction in final height compared with their unirradiated controls. Leaf width was also reduced in almost all cases. Whilst in some parental combinations the direction of this change is compatible with the concept of restricted transfer of genes from the original pollen parent in other cases it is not. Instead the consistent trend across all generations is better explained as a consequence of the expression of deleterious mutations that lead to a general reduction in vigour. Differences between the two backcross generations provide some evidence of selection in the M1 pollen against radiation damage, acting in general to improve vigour. It is concluded that the maternal trends previously reported in this species were entirely the result of induced mutations, reducing the expression of the characters concerned. No evidence can be found from this species for the existence of a mechanism for gene transfer by DNA fragment incorporation.
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Cornish, M., Werner, C. Gene transfer in Nicotiana rustica by means of irradiated pollen V. Quantitative characters. Heredity 55, 321–326 (1985). https://doi.org/10.1038/hdy.1985.114
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DOI: https://doi.org/10.1038/hdy.1985.114