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Rootstocks Transformed withrolA, B, C Genes Enhance Rose Flower Production

“…Rootstock type T2, expressing only the rot B gene, performed as the control for all parameters measured. All results are in line with the laboratory experiments that were carried out with these rootstocks by Van der Salm and coworkers (15). Differently from the laboratory experiments, we have now been able to follow the performance of the transgenic rootstocks during a whole production cycle, including two winters and one summer, and for three cultivars that are known to have different production levels, under identical conditions for all tested rootstock/scion combinations.…”

“…Measured over a three months period, axillary bud release increased with a factor 6 at 15 oc (0, 1 to 0,6 basal shoot per plant) and a factor 3 (0,3 to 1,3) at 20 °C. (15). Based on these results it was expected that the application of rolA,B, C transformed rootstocks would provide an opportunity for growers to produce more efficient at a lower temperature.…”

“…The levels of cytokinin in the sapstream are suppressed by auxins which are mainly formed in apices and shoots and transported towards the roots. Based on these assumptions, Van der Salm et al (10) reasoned that genetic modification of rootstocks with genes that influence auxin or cytokinin production or sensitivity might lead to stimulation of axil-lary bud release in the scion cultivar. Three genes, rotA, B and C, from Agrobacterium rhizogenes, which were already used for improvement of the rooting ability of other woody species such as kiwi and apple (11, 12), were chosen for genetic modification.…”

“…Dieleman and coworkers (20) found a correlation between cytokinin levels present in the bleeding sap and Special Issue 69 the number of axillary buds that are released at the basal part of the plant after harvesting the flowering shoot. Therefore, Van der Salm et a!., (15) reasoned that the increased axillary bud release found for the rot A,B,C rootstocks was most probably due to increased cytokinin levels. From our experiments we hypothesize that during the flushes the release of extra cytokinins in the rot A,B,C rootstocks is not strong enough to overcome the auxin-directed inhibitory effect on axillary bud release, but once the flush of flowering shoots is harvested, the enhanced levels of cytokinin are responsible for outgrowth of more axillary buds, resulting in a new strong flush of shoots.…”

Horticultural characterization of a tetraploid transgenic plant of <i>Tricyrtis</i> sp. carrying the gibberellin 2-oxidase gene

“…High pollen fertility in G2-55 offers a possibility of using this transgenic line as a cross-breeding material. In our previous study, several horticulturally attractive interspecific hybrids have been produced in Tricyrtis via ovule culture (Tasaki et al 2014). Production of hybrid plants showing not only transgene-induced dwarfness but also other novel morphological characteristics is now in progress using G2-55 as one parent.…”