Bns. Murthy et al., THIDIAZURON - A POTENT REGULATOR OF IN-VITRO PLANT MORPHOGENESIS, In vitro cellular & developmental biology. Plant, 34(4), 1998, pp. 267-275
TDZ (N-phenyl-N'-1,2,3-thidiazol-5-ylurea) is a substituted phenylurea
compound which was developed for mechanized harvesting of cotton bell
s and has now emerged as a highly efficacious bioregulant of morphogen
esis in the tissue culture of many plant species. Application of TDZ i
nduces a diverse array of cultural responses ranging from induction of
callus to formation of somatic embryos. TDZ exhibits the unique prope
rty of mimicking both auxin and cytokinin effects on growth and differ
entiation of cultured explants, although structurally it is different
from either auxins or purine-based cytokinins. A number of physiologic
al and biochemical events in cells are likely to be influenced by TDZ,
but these may or may not be directly related to the induction of morp
hogenic responses, and hence, the mode of action of TDZ is unknown. Ho
wever, the recent approaches applied to study the morphogenic events i
nitiated by TDZ are clearly beginning to reveal the details of a varie
ty of underlying mechanisms. Various reports indicate that TDZ may act
through modulation of the endogenous plant growth regulators, either
directly or as a result of induced stress. The other possibilities inc
lude the modification in cell membranes, energy levels, nutrient uptak
e, or nutrient assimilation. In this review; several of these possibil
ities are presented and discussed in light of recently published studi
es on characterization of TDZ-induced morphogenic effects.