ISHS Acta Horticulturae 336: II International Symposium on In Vitro Culture and Horticultural Breeding
A MODEL SYSTEM FOR STUDYING ROOT REGENERATION IN WOODY SPECIES |
| Authors: | M. Welander, N. Pawlicki |
| Keywords: | Anatomy, tissue culture, Malus, RNA probes |
| Abstract:
The highest mean rooting percentage (94%) and number of roots (5.9) for apple rootstock Jork M9 were obtained with 24.6 μM IBA in the rooting medium and 1 day of dark treatment before the stem discs were transferred to a growth regulator-free rooting medium in the light. Anatomical studies revealed increased cambial activity after 2 days. At day 3, cell divisions were frequent around vascular bundles. At day 4 and 5, cells with densely stained cytoplasm and enlarged nucleoli appeared between the bundles external to the phloem. These meristemoids were the first evidence of future roots. At day 6, more or less differentiated root primordia developed from the meristemoids. From day 7, root primordia started to emerge from the stem cortex, and after 9 days the roots projected well beyond the stem disc surface. Interesting cDNA clones are currently being investigated by hybridization of RNA probes to RNA isolated from stem discs at different times during the root initiation. These probes are being used to develop a suitable technique for in situ hybridization using cryosections. | |
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