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

POLYAMINES METABOLISM DURING SOMATIC EMBRYOGENESIS IN VITIS VINIFERA L.

TASSONI A.*, BERTOLDI D.*^,**, MARTINELLI L.**, BAGNI N.*

* Dipartimento di Biologia e Centro Interdipartimentale per le Biotecnologie, Università di Bologna, Italia

tassonia@alma.unibo.it

** Istituto Agrario, San Michele all’Adige, 38010, Trento, Italia

grapevine, polyamines, somatic embryogenesis, Brachetto g.l., Chardonnay

Aliphatic polyamines are ubiquitous growth regulators affecting both in vivo and in vitro plant growth and development, being involved in several morphogenic processes related to their action in cell division.

With the aim of better understand the developmental programs involved in regeneration of grape plants, polyamine (putrescine, spermidine and spermine) contents and polyamine biosynthetic enzyme activities, were assayed during somatic embryogenesis induced in callus cultures obtained from Vitis vinifera anthers (Chardonnay cultivar) or ovaries (Brachetto a grappolo lungo cultivar). The analysis were conducted on samples of callus, embryogenic callus, embryos at different stages (e.g. globular and torpedo) and plants germinated from embryos. Polyamine content (nmol unit^-1) both free and conjugated to hydroxycinnamic acids (PCA-soluble fraction), resulted higher in the cv. Brachetto g.l. than in the cv. Chardonnay, reaching the highest levels in the fully-developed embryo stage (large embryos). In general, putrescine was present in a greater amount with respect to spermidine and spermine, in all the samples analysed. Ornithine decarboxylase (ODC) activity was higher than arginine decarboxylase activity (ADC) in all the samples of both cultivars, with a maximum in roots of germinated plants. Even S-adenosylmethionine decarboxylase (SAMDC) activity displayed a similar trend. All the activities were measured in the supernatant and in pellet fractions, reconfirming the presence of ODC and ADC activity in the particulate fraction. Contrarily to what generally stated in the literature, a consistent SAMDC activity, was measured in the particulate fraction, being in particular samples, such as roots of germinated plants, 50% higher than the SAMDC activity in the soluble fraction.

Further analysis, by northern blot, are actually in progress to evaluate the expression level of ADC, ODC and SAMDC transcripts, in the different developmental stages of Brachetto g.l. and Chardonnay somatic embryogenesis