Cucurbit Genetics Cooperative Report 10:62-63 (article 33) 1987
Obtention of Embryos and Plants From In Vitro Culture
of Fertilized Ovules of Cucumis melo 5 Days After Pollination
A. Sauton
INRA, Station d'Amèlioration des Plantes maraîchères,
84140 Montfavet, France
In Cucurbitaceae, failure of interspecific hybridization may be due to
an early abortion of the hybrid embryos (3). Young Cucumis embryos
when they are extracted at globular or heart shape stages are sometimes
able to continue their differentiation in vitro (1). However
it is often difficult to isolate embryos at these stages.
The results reported here involved the development of a new in
vitro culture technique to obtain embryos from very young fertilized
ovules of Cucumis melo.
Plants of melon commercial F1 hybrid ('Alfa') were grown in
a greenhouse under normal light and culture conditions. Plants were self
pollinated. The ovaries were harvested 5 days after pollination.
They were surface sterilized by dipping for 10 min. in a solution of
10% calcium hypochlorite with a few drops of tween 20 emulsifier. Ovaries
were then rinsed three times with sterile distilled water and aseptically
transferred to moistened sterile filter paper in Petri dishes. Ovules were
excised under binocular, placenta tissue was carefully removed.
Twenty naked ovules were placed in a 5 cm Petri dish filled with the
following culture medium :
- macronutrients and micronutrients as described for pepper anthers culture
(2) but used half strength.
- Na2EDTA 18.65 mg/l and FeSO4 13.9 mg/l
- Fuji and Morel vitamins as detailed for pepper (2)
- sucrose 20 g/l; Agar 10 g/l.
pH of the medium was adjusted to 5.9 before autoclaving at 115°C for
20 min. Culture was made at 25°C with 12 hrs light per day.
Germination of the embryos occured within 3 or 4 weeks. One ovule gives
always only one embryo. Embryos grew very fast and developed into complete
plants; in about four weeks they reached a developmental stage suitable
for transplanting to soil.
This technique presents 2 advantages:
- the artificial culture can start 5 days only after pollination. That may
be important in the case of early embryo abortion;
- isolation of young ovules is easier than extraction of embryos at the
globular stages.
So its application to interspecific crosses in this genus can be envisaged.
Literature Cited
- Custers, J.B.M. 1981. Heart shape stage embryos of Cucumis
species more successful in embryo culture than advanced stage embryos. Cucurbit
Genetics Coop. Rpt. 4:48-49.
- Dumas de Vaulx, R., D. Chambonnet, and E. Pochard. 1981. Culture in
vitro d'anthères de piment (Capsicum annuum L.): amélioration des taux d'obtention de plantes chez différents
génotypes par des traitements à +35°C. Agronomie 1:859-864.
- Niemirowicz-Szczytt, K., and B. Kubicki. 1979. Cross fertilization
between cultivated species of genera Cucumis L. and Cucurbita L. Genetica Polonica 20:117-124.
Acknowledgements:
My thanks are due to Research GIE of Clause/Limagrain for financial support.
I am also grateful to R. Dumas de Vaulx for his helpful comments.
