The herbicide 2,4-D (2,4-dichlorophenoxyacetic acid) is a plant growth regulator for callus induction and somatic embryogenesis in tissue culture protocols. Research has shown that exposure to 2,4-D causes a number of environmental and health problems. Routine laboratory work involves the use of 2,4-D in the preparation of culture media, thus generating culture media with 2,4-D residues, the disposal of which is often improper. Therefore, this study aimed to determine the residual content of 2,4-D in MS (Murashige and Skoog), agrowth medium used in plant tissue cultures, after callus development. MS media were used from callus cultures of bananeira (Musa sp.) and basil (Ocimum basilicum L.). Callus cultures were supplemented with 2,4-D at concentrations of 1.0 and 0.5 mg.L-1, respectively. MS media were also evaluated in the absence of plant culture at the 0.2; 0.5 and 1.0 mg.L-1 concentrations of 2,4-D under light and dark conditions for a period of one month. Banana callus cultures consumed about 79% ± 0.27% of 2,4-D in the culture medium after two months. After three months of culture, it was not possible to detect 2,4-D in basil callus culture since the values found were below the detection limit (LOD ≤ 0.096 mg.L-1). Light does not appear to influence the degradation of 2,4-D in the culture medium. Results suggest that the concentration of 2,4-D residues depends on the species cultured. Improper disposal of these media might be a source of ignored and, hence, environmental contamination, depending on 2,4-D concentration and volume of mediawaste.

No abstract

This study aimed to evaluate the development of Canavalia ensiformis seedlings under high concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) in different substrates. In the first analysis, seeds from different origins were disinfected and introduced into a modified Leonard vessel (PET vessel) containing washed sand or washed sand plus vermiculite substrates and under high concentrations of 2,4-D (0 - control, 250 and 500 mg/L). For a second analysis, seed germination, callogenesis and contamination in different concentrations of 2,4-D (0 - control, 20, 40, 250 and 500 mg/L) were evaluated with sterile sand as substrate. Results showed that higher concentrations of 2,4-D could induce larger areas of callus formation. At a concentration of 40 mg/L of 2,4-D, germination in riparian forest substrates washed sand resulted in root growth and callus formation without contamination. Although C. ensiformis seeds showed tolerance to regions with high concentrations of 2,4-D, they do not demonstrate phytoremediation capacity for this herbicide since it caused damage to the plant’s initial development.

No abstract

Evaluation of phytoremediation capacity under aseptic, controlled conditions can be achieved with the use of plant tissue cultures as a model, eliminating interference from the physical environment. Herein, we developed an in vitro culture protocol for green manures of Crotalaria juncea, C. spectabilis and Canavalia ensiformis, each of which contributes to a sustainable cropping system. In particular, we studied their behavior in the presence of the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid). Disinfection of C. juncea seeds was efficient, and plantlets presented the best development of roots, stem and leaves. Thus, subsequent experiments were conducted only with C. juncea. For 2,4-D tolerance tests, C. juncea seedlings were transferred to Murashige and Skoog (MS) solid media under the following concentrations of 2,4-D: 0 (control), 0.2, 0.5 and 1.0 mg L-1 for a 30-day period. After this period, MS culture media for C. juncea was analyzed by HPLC for quantification of residual 2,4-D. C. juncea development was observed to be sensitive to 2,4-D toxicity; however it was observed 2,4-D reduction in the media. Nonetheless, field assays are still necessary to evaluate the feasibility of using it as a phytoremediator, as well as determine the influence of environmental and plant density variables on 2,4-D absorption capacity from soil.