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 - 5.52

STUDIES ON IN VITRO EMBRYO CULTURE OF OLIVE

P. POLLACCI, M. MENCUCCINI

Istituto per i Sistemi Agricoli e Forestali del Mediterraneo (ISAFOM), Sezione di Perugia

Olea europaea, embryo culture, germination, in vitro culture

The olive tree (Olea europaea L.) has a long-juvenile phase in field condition (some cases more than 10-15 years to reach flowering) and this make very difficult the genetic improvement by the traditional breeding technique.

Some authors found olive embryonal dormancy and germination of seeds are slow and uneven events, and these make the propagation of new genotypes more difficult.

The purpose of this work was to study the effect of time and temperature storage and teguments presence on growth of olive mature embryos. Fruits of cv Leccino, obtained by free-cross-breeding, were randomly sampled on November. After removing the fleshy exocarp and mesocarp, stones (endocarp, seed coat, endosperm and embryo) were washed and dried. Stones were broken and seeds were sterilized by mild shaking for 10 minutes in a 10% commercial preparation of sodium ipoclorite (4,9 % active Cl) and abundantly rinsed in sterile water. The embryos extracted under sterile conditions, were cultured in test-tubes with agar medium (EZ) in growth chamber at 24±1°C to the light. In vitro cotyledons, radicle and epicotyle development percentage and the presence/absence of callus were evaluated after 8 weeks, whereas in vivo plantlets survival was evaluated after 12 weeks from transplant in greenhouse. Stones, seeds (seed coat, endosperm and embryo) and embryos have been treated as following:

A) Stones to 4°C for 2 months, then embryos in EZ in growth chamber;

B) Stones to 4°C for 10 days, then embryos in EZ in growth chamber;

C) Seeds to 4°C for 2 months, then embryos in EZ in growth chamber;

D) Seeds to 4°C for 1 month, then embryos in EZ in growth chamber;

E) Seeds to 4°C for 1 month with water, then embryos in EZ in growth chamber;

F) Seeds to 4°C for 10 days, then embryos in EZ in growth chamber;

G) Embryos in EZ to 4°C for 2 months, then in growth chamber;

H) Embryos in EZ to 4°C for 1 month, then in growth chamber;

I) Embryos in EZ to 4°C for 3 months, then in growth chamber;

L) Embryos in EZ to 4°C for 10 days, then in growth chamber;

M) Embryos in EZ to 4°C for 5 days, then in growth chamber;

N) Embryos in EZ immediately in growth chamber (control).

Results shown the developed cotiledons percentage of "D", "E" and "F" theses was consistently higher (100 %), at contrary of the "N" thesis (40 %). The root development was observed in 55% of the cases for the thesis "D" and 40-45% in the theses "A", "E" and "F", while only 30% in the control. Similar trend was also estimated in the growth of the epicotyle. The thesis "G" has a strong presence of callus (a double number of cases in comparison to the control). Plantlets survived in vivo after the acclimatation in greenhouse have reached 80 % in the thesis " F " against 30 % of the control.

In conclusion, cold storage (4°C) for 10-30 days increases in vitro growth of mature embryos and in vivo percentage plantlets survival in comparison with the embryo culture standard procedure.