Influence reciproque de quelques substances de croissance dans la culture de tissu de topinambour (Helianthus tuberosus L. var. ‘Violet’). II. Le comportament du Tissu

The influence of the culture medium on the explants of Jerusalem artichoke was studied. The concentration of the growth substances in the medium was 1 ppm IAA and NAA and 0.1 ppm 2,4-D. Moreover, labelled auxins were added: IAA-1-14C, IAA-2-14C, (IAA-2)-14C, NAA-1-,4C and 2,4-D-l-14C. Eight hours extraction of the tissue by methanol at 4 0C using a magnetic stirrer gave the best results. It was proved that the growth substances were absorbed and fixed in the tissue as whole molecules. The quantity of the fixed degraded molecule was not significant. One hour after absorbing the IAA the substance was incorporated into the tissue. It took 2-3 hours before NAA was incorporated and 48 hours before 2,4-D was fixed. This proves that in the tissue an adaptation process had to take place before the auxin could be incorporated. The next problem to be studied is how the incorporated substance will be used after transfer of the tissue to a medium without auxins.