[Inhibition of the auxin-induced root-formation in etiolated pea epicotyls by histone and antimetabolites of the RNA- and protein synthesis].

Differentiation of tracheids and root formation in etiolated pea epicotyls is inhibited by actinomycin D, 5-bromouracil, calf thymus histone and chloramphenicol 48 hours after culture initiation. The formation of spots with embryonic cells is thereby not suppressed. The bromouracil-inhibition is competitively reversed by thymine. 2-Thiouracil and 8-azaguanine also inhibit root formation 48 hours after culture initiation, but this effect is not reversed by uracil or guanine. The temporal spectrum of root-inhibition induced by 5-bromouracil, calf thymus histone, chloramphenicol or actinomycin D differs from that induced by 2-TU. Like cystein and dinitrophenol, 2-TU inhibits root-formation entirely during the first five days after culture initiation.Increasing amounts of indole-3-acetic acid cause the formation of an increasing number of roots and the earlier appearance of adventive roots and bring about a prolonged phase of activity, which is inhibited by 5-bromouracil or histone. Moreover, the phases of inhibition start earlier.The temporal position of the root-inhibition phases depends on the season.