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Growth of Fragments of mature Pumpkin Embryos cultivated in vitro

Sibila Jelaska ; Hrvatska

Sažetak

The growth of the segments A and B of mature embryos of pumpkin (Cucurbita pepo L.) has been studied in vitro. The segments were 0,5—0,75 mm long. The segment A corresponded to the upper part of hypocotyl tissue with epicotyl and apical meristem, the segment B to the lower part of the hypocotyl, which was deprived of correlative relations.
The experiments have given the following results: When submerged, the embryo segments did not show any signs of organogenesis and the increase of fresh and dry weight was considerably smaller than in segments which were cultivated on the surface of the medium. From three different nutrient media, which were used, (Heller’s Rob- bin’s and White’s) Heller’s medium was the most suitable one and caused the highest increase in fresh and dry weight of explants. However, the segment A was able to grow into a normal plant only on Murashige—Skoog medium. These facts are quite in agreement with our further investigations on the needs of pumpkin tissue for a basic medium rich in salts e. g. the MS-medium.
When cultivated on the surface of a basic nutrient medium, say Heller’s medium, the segments differentiated into hypocotyls (the A- segments became 4—5 cm long, and the B-segments 0,5—1 cm) and into weak roots (on the proximal side of segments). The application of IAA in high concentrations (10-5) induced roots also on the distal part of the segments, especially on B-segments. As a rule the roots were more vigorously developed in B-segments.
The addition of coconut milk in concentration of 10% stimulated the development of the hypocotyl, just as the addition of the IAA in a concentration of 10% It is interesting that after a cultivation with adenine the A-segments were more vigorous than in the control. An addition of 0,5% yeast extract to the medium containing coconut milk also allowed a vigorous growth of the hypocotyl.
In concentrations 10-6 and 10-5 the IAA increased the number of induced roots, disturbed the polarity of their formation and inhibited their elongation.
High concentrations of growth stimulators, as e. g. 2,4-D (10-6 and 1CT5) or 2,4,5-T (10-6 and 10-5) inhibited any organogenesis. The addition of 2,4-D (10-6) to the medium containing coconut milk, prevented the action of coconut milk so that the development of hypocotyl and roots was inhibited as compared to the growth of undifferentiated tissue which was slightlly stimulated.
In concentrations of 10-8 and 10% kinetin had a strong inhibitory effect on the development of hypocotyl even without any addition of other substances. At a concentration of 10-7 the kinetin enabled the development of the epicotyl with the apex.
The addition of both kinetin and IAA (both in concentration 10-6) strongly inhibited the development of hypocotyl.
In addition to the inhibition of the hypocotyl differentiation high concentrations of growth stimulators (e. g. 2,4-D) induced cell dedifferentiation and the appearance of cells of embryonic type, about 20 micro m in diameter.

Ključne riječi

Hrčak ID:

157256

URI

https://hrcak.srce.hr/157256

Datum izdavanja:

31.12.1973.

Podaci na drugim jezicima: hrvatski

Posjeta: 1.040 *