ISHS Acta Horticulturae 287: II International Symposium on Protected Cultivation of Vegetables in Mild Winter Climates
RESPONSE TO IN VITRO CULTURE OF IMMATURE EMBRYOS OF CERTAIN GENOTYPES OF PHASEOLUS VULGARIS |
| Authors: | P.J. Bebeli, P.J. Kaltsikes |
| Abstract:
As part of a study aimed at producing useful somaclonal variation in cultivated plants we attempted the culture in vitro of immature embryos of Phaseolus vulgaris L., a species considered somewhat recalcitrant in this respect. The cultivars used were : EISE, BORLET, CONTENDER and CHAOULI. MS salts, supplemented with 2.5 mg/lit BAP and solidified with 0.8% agar were used as the nutrient medium. After dissection the whole structure (cotyledons+embryo) was placed on the medium with the embryo in contact with it. When the long axis of the cotyledons was smaller than 1 mm, the whole structure turned white after a while and no response was observed. When the axis was longer than 3.5 mm precocious embryo germination was observed a few days after the initiation of culture. The callus that was formed soon turned brown. This soft, watery, transparent, brownish callus, with a few whitish areas on its surface, represented the typical non-morphogenetic callus for the genotypes studied. The best response was observed when the long axis of the cotyledons was 2.5–3.0 mm in length. In this case the whole structure swelled up. Where the cotyledons were in contact with the medium, callus formation was initiated. This callus did not seem to be morphogenetic. In the cases where regeneration was observed, the embryo swelled up but it did not produce the root that accompanies precocious germination. Instead it gave rise to a light-green callus which soon began forming shoot buds and distinct, individual leaf structures. A third kind of callus was also observed. It was dark-green and glossy. On the surface of this callus globular structures and/or green leafy structures (shoot-tips) with trichomes which were more fragile were procuced. Occasionally a thick solid green callus was observed which was smooth, resembling a piece of cactus. The percentages as well as the type and form of response were recorded for the genotypes studied. Regenerated plants were obtained. | |
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