Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 4.11

Modifications of growth pattern in kiwifruit and cherry induced by the T-DNA genes of Agrobacterium rhizogenes

R. BIASI*, P. GUTIERREZ*, M. MUGANU*, P. MAGRO**, M. BERNABEI***, E. RUGINI*

*) Dipartimento di Produzione Vegetale, Università degli Studi della Tuscia, Facoltà di Agraria, 01100 Viterbo, Italy

**) Dipartimento di Difesa delle Piante, Università degli Studi della Tuscia, Facoltà di Agraria, 01100 Viterbo, Italy

***) Dipartimento di Tecnologie, Ingegneria dell'Ambiente e delle Foreste, Università degli Studi della Tuscia, Facoltà di Agraria, 01100 Viterbo, Italy

genetic transformation, Agrobacterium rhizogenes, kiwifruit, cherry, vegetative habit, growth pattern, rol genes

Growth habit of the 5-year-old kiwifruit vines of the transgenic female, cv Hayward, and the male selection GTH, and the cherry rootstock Colt, has been evaluated in an authorised open field since 1998.

Kiwifruit (Actinidia deliciosa A. Chev.), genetically modified, were obtained in vitro from leaf explants co-cultivated with A. tumefaciens carrying the rolABC and rolB genes of A. rhizogenes under natural promoter (Rugini et al, 1991). The introduction of the rolB does not seems to modify plant morphology, while the simultaneous introduction of the three associated genes, rolABC, induced plant modification regarding the phenology stages and plant architecture in both female and male vines. Bud burst was delayed, resulting in a lower number of lateral shoots compared to untransformed control plants; however, the basal buds always developed normally, showing a marked basitony behaviour. The lateral shoots in transgenic plants, beside having shortened internodes, carried leaves in upright position, with a reduced lamina surface and increased thickness. In addition, the plants showed an increased of water retention during a waterless stress period, which could be due to a modified hydraulic conductivity in the different xylem anatomy, since the elements were smaller and pits were extended in all cell walls of vessels. Nitrogen content in the leaves was also increased in almost all somaclones tested.

Cherry rootstock "Colt" (Prunus avium x Prunus pseudocerasus) plants were also produced in vitro from transgenic roots induced by A. rhizogenes wild type (Gutierez-Pesce et al., 1998). The plants showed variability in architecture of the growth pattern within the regenerated somaclones: 50% did not show the characteristic of "hairy root phenotype" so their growth pattern was similar to untransformed control plants; the other 50% of the transgenic somaclones showed a reduced total growth (height and diameter) resulting in a spur habit respect to control plants, i.e. marked short internodes and reduced vigour, a leaf area drastically reduced, as well as length of the petiole and fresh and dry weight reduction, while chlorophyll and nitrogen content did not change in any of the transgenic somaclones. Regarding flowering, all replicates of one transgenic somaclone (somaclone A) never produced flowers. The period of blossom in the rest of the transgenic somaclones was delayed by several days, while the morphology or the flowers was similar to the untransformed control plants. Delayed was also the rest period. When transgenic rootstocks were grafted with normal scion, in some case, the bimember plant size resulted reduced. The rooting ability of both herbaceous and hardwood cutting of transgenic somaclones with "hairy root phenotype" aspect, was unexpectedly drastically low.