Acta Botanica Croatica, Vol. 25 No. 1, 1966.
Izvorni znanstveni članak
The effect of 2-naphthoxyacetic acid and 2,4-dichlorophenoxya- cetic acid on the cotyledon tissue of Pumpkin (Cucurbita pepo L.) Growing in Vitro
Sibila Jelaska
; Hrvatska
Sažetak
The behaviour of tissue fragments of the cotyledon of the pumpkin (Cucurbita pepo L.) cultivated in vitro, with and without the addition of growth regulators 2-,naphthoxyace|tic acid and 2,4-dichlorophenoxy- acetic acid in concentrations from 10"9—10-5 to the nutrient medium, has been studied.
When cultivated on the standard medium without any addition of growth regulators the tissue of the cotyledon developed a discrete callus and well-developed roots of normal appearance on the cut surface of the proximal part. The whole tissue fragment enlarged twice its volume, owing to hypertrophy of mesophyle cells, and to cell divisions inside the tissue, especialy in the neighbourhood of the conducting systems (vessels). The nutritive medium did not inhibit the activity of the proximal side and it behaved equally regardless whether it was oriented upside or downside.
At both orientations the distal side showed only the process of wound healing. In this nutrient medium, having no regulatory substances, the cells showed a tendency to hyperhydrataceous transformation.
The applied growth regulators 2-naphthoxyacetic acid and 2,4- -dichlorophenoxyacetic acid in concentrations of 1CT7 to 10~5 showed striking and similar effects on the growing tissue.
At these concentrations both substances inhibited the development of the roots (even if they had already been preformed) regardless whether the proximal or the distal part was deeped into the medium.
The proximal as well as the distal part of the tissue fragment proliferated well and developed into big masses of undiferentiated tissue the volume of which was the greater the higher the concentration of the growth regulator employed. The proximal side was more sensitive and reacted more intensely than the distal side.
If the distal side of the tissue fragments was oriented outside of the medium it did not react with the growth substances, even not at their highest concentrations.
The histological investigations of the newly developed cell masses shoved that they consist of parenchimatic cells and conducting elements. These elements appeared either associated in clusters, series, or as single cells. Single tracheidal elements were especially frequent. At higher concentrations of growth regulators in the newly developed cell masses, islets consisting of small' cells, resembling the cells of vegetative points, were formed. According to all the above facts the tissue of the cotyledon of Cucurbita pepo appears to be very sensitive to the strong growth regulators applied. Thus it seems to be very probable that by further investigation of combined effects of different growth regulators it would be possible to obtain a strain of undifferentiated tissue which could be permanently subcultivated.
Ključne riječi
Hrčak ID:
154232
URI
Datum izdavanja:
31.12.1966.
Posjeta: 785 *