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

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

SOMATIC EMBRYOGENESIS IN ROSA HYBRIDA L. CULTIVARS

ESPOSITO S., DIRETTO G., FILIPPONE E.

Dipartimento di Scienze Agronomiche e Genetica Vegetale, Università degli Studi di Napoli “Federico II”, Via Università 100, 80055 Portici, Italy

filippon@unina.it

Rosa hybrida, somatic embryogenesis, tissue culture, biotechnology, ornamental crops

Rose is one of the most important ornamental crops grown worldwide; therefore it is very interesting to obtain new varieties with improved horticultural and ornamental traits to satisfy commercial demands. In order to introduce genetic changes to overcome the limitations of classical breeding, it is possible to utilize biotechnological approaches involving tissue culture techniques and genetic manipulation. However, it is difficult to achieve them for rose species, as also reported in the literature.

In this study, ten different cultivars of Rosa hybrida were tested for their capacity to differentiate somatic embryos using the protocol reported by Marchant et al. (Plant Science 120: 95-105. 1996). Experiments were performed on three different explant sources: leaves, petioles and stipules. Satisfactory callus induction rates were obtained for all cultivars after 2 weeks of culture, ranging from 62.5% in cv RB to 97.7% in cv RC leaf explants, from 70.2% in cv RGO to 100% in cvs BNC and TEX petiole explants and from 55% in cv RGO to 100% in cvs BNC and Glad Tidings stipule explants. Somatic embryogenesis was only induced in four cultivars and germinated somatic embryos, suitable for further transplantation, were obtained after 25 weeks of in vitro culture. The frequency of petiole explants giving rise to embryogenic callus ranged from 14.5% in cv. RF to 41.2% in cv. RGA, whereas the frequency of stipule explants producing embryogenic callus ranged from 21.7% in cv. RF to 35.3% in cv. Glad Tidings. Leaf explants did not produce any embryogenic calli, except in cv. RF at frequency of 31.4%.

Germination of somatic embryos occurred in cv. RGA from petiole derived calli and in cv. Glad Tidings from petiole and stipule derived calli. They gave rise to 50 plantlets originating from different embryogenic events. These plantlets were propagated and then transferred to greenhouse conditions in order to characterize them at the phenotypic, karyotypic and molecular level.

These data confirm that rose is strongly dependent on genotype for in vitro manipulation; now we are exploiting somatic embryogenesis obtained in our laboratory to carry out genetic transformation experiments with Agrobacterium tumefaciens and particle bombardment.