Gene transfer in Nicotiana rustica using irradiated pollen

Abstract

In spite of reports of widespread matromorphy—the occurrence of diploid plants whose genomes are exclusively maternal in origin—in Nicotiana¹ and in other genera^2,3, attempts to induce it in pure-breeding material of Nicotiana rustica have met with little success^4,5. When heavily irradiated pollen from one variety is used as the inducer on a contrasting variety acting as maternal parent, the progeny, while showing a greater resemblance to the maternal parent, are not true matromorphs because they usually have at least one characteristic of the paternal parent. At the highest dose of γ-irradiation, 20 krad, the progeny usually acquire from the paternal parent only one or a small sample of the many heritable characteristics by which the two varieties differ. By selecting within these progenies we have shown here that lines can be isolated with the characteristics of the pure-breeding maternal variety but with the exception of a specific characteristic transferred from the paternal variety. To achieve the same end by conventional means would require a combination of many generations of recurrent backcrossing and selection.