2,4-D is a broadly used auxin herbicide. The presence of the 2,4-D synthetic auxin in the medium is imperative for long-term BY-2 tobacco suspension viability. The precise mechanism of this symbiosis of the suspension and the synthetic auxin remains unclear. Our goal was to study the hormonal regulation of the growth of the cell suspension; and to describe the experiments clarifying the interaction between the chosen growth regulators and phytohormones on the cellular level, specifically between the 2,4-D synthetic auxin and the native stress phytohormone - ethylene. This study examined the influence of low 2,4-D concentrations stimulating cell growth in vitro as well as the influence of high herbicide concentrations on the model tobacco BY-2 suspension. The culture took 6 days. Different parameters were evaluated, including the influence of different 2,4-D concentrations on the production of the phytohormone ethylene and its precursor 1-Aminocyclopropane-1-carboxylic acid (ACC) in the tobacco cells. The content of 2,4-D in the cells and the medium was established. The observations of the morphological changes showed that a heavy impregnation of the cell walls taking place depending on the concentration of 2,4-D. A dramatic increase in protective polysaccharides and a remodulation of the cell walls by the formation of a pectin shield in artificial conditions were expected and observed. At the same time, massive production of the stress phytohormone ethylene took place, and, because of that, plant mutagenicity, anomalous tumour-type proliferation growth, and the production of supercells were observed. The hypothesis of the protective shield is discussed.

• Keywords
• 2,4- dichlorophenoxyacetic acid, 2,4-D, BY-2 cell suspension, Ethylene, Pectin shield, Plant mutagenicity,
• MeSH
• Ethylenes MeSH
• Herbicides * pharmacology   MeSH
• 2,4-Dichlorophenoxyacetic Acid pharmacology   MeSH
• Indoleacetic Acids MeSH
• Gene Expression Regulation, Plant MeSH
• Plant Growth Regulators pharmacology   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• ethylene MeSH Browser
• Ethylenes MeSH
• Herbicides * MeSH
• 2,4-Dichlorophenoxyacetic Acid MeSH
• Indoleacetic Acids MeSH
• Plant Growth Regulators MeSH