Mitotic activity auxins

Although in the latter case gibberellin appears to be primarily responsible for the increased mitotic activity and auxin for differentiation of the newly formed cells, auxin may also be involved in the primary cambial activation mechanism (25). After the discovery of the gibberellins several studies showed conclusively that auxin and gibberellin have separate, sometimes additive and sometimes syner-... 

Auxins modify mitotic activity in cell types ranging from yeast (Sharma and Baruah 1975) to bovine muscle cells (Basrur etal. 1976). The high levels of auxin in human cancer tissue have even led to the suggestion that lAA plays some role in the acceleration of division in animal cancer cells (Yamaki et al. 1974). 

In some cases, changes in auxin levels show a positive correlation with changes in mitotic activity. Nishinari and Yamaki (1976) noted that, in synchronized tobacco cell cultures, there is an increase in the activity of lAA-synthesiz-ing enzymes preceding an increase in the level of auxin, and that these events occur just prior to the increase in the number of dividing cells. The authors concluded that synthesis of free lAA may initiate mitosis. A dependence of cell division on internal auxin concentration in Acer pseudoplatanus was also shown by Lequay and Guern (1977). 

---