Further Characterization ofrollCTransgenic Tetraploid Potato Clones, and Influence of Daylength and Level ofrolCExpression on Yield Parameters

摘要

AbstractTetraploidrolCtransformants have been analyzed considering the level ofrolCexpression and yield parameters. InrolCtransformants a maximum of five integrated copies of the gene were detected by Southern analysis. A relation between copy number of therolCgene, phenotypicrolCexpression and intensity of morphological alterations was established. Three experiments were performed to assess the differential effect of therolCgene on yield and its interaction with growth factors. In the first experiment, the influence of day length on plant morphological and physiological characters was studied. The phenotype of the transgenic plants with a lowrolCexpression was like the control under the two day‐regimes tested, while the intermediate expressing genotype showed a different reaction. In the second and third experiment, tuber yield, tuber number and weight per tuber were recorded under short and long day conditions. When grown in smaller pots of 1.15 1 volume, the control plants had the highest yield of tubers under both day lengths tested. Yield decreased with increasingrolCexpression. Tuber number revealed to be genotype dependent: it was higher for lowrolCexpressing plants and lower for intermediaterolCtransformants (Experiment 2). In the third experiment the influence of variable pot size and shape was analyzed for one clone with intermediate and two with low level ofrolCexpression. Remarkable differences between pots and flat boxes of the same volume were noted for tuber yield and number: Under the two conditions the control clone and the lowrolCexpressing genotypes gave similar tuber yield and number in both growth containers, whereas therolCintermediate genotype yielded significantly more in flat boxes. The effect of variable hormonal levels induced in transgenic plants through prokaryotic genes are discussed with the existence of non‐predictable genotype in relation to environmental interactions. It is concluded that at least the agronomic performance of potatoes transformed with these genes cannot be predicted on the basis of simple linear relationships among the expression of the gene and of the tra