Regulación de la rizogénesis adventicia en clones recalcitrantes de Eucalyptus dunnii a través de la aplicación de auxina exógena

Currently, Eucalyptus dunnii has become one of the most relevant forest species in Uruguay due to its rapid growth and ability to adapt to low temperatures. However, it presents some limitations, particularly regarding clonal propagation, due to its difficulty in adventitious rooting. This study aimed to evaluate how different exogenous auxins affect the rooting of Eucalyptus dunnii mini-cuttings, as well as some of the molecular mechanisms involved in this process. Two clones with contrasting rooting capacities were used, and four treatments were evaluated: control, indole-3-butyric acid (IBA), naphthaleneacetic acid (NAA), and the IBA+NAA mixture. Rooting percentage was measured, and variables related to root structure, such as root number and length, were analyzed. Additionally, the expression of the Transport Inhibitor Response 1 (TIR1) gene was evaluated by RT-qPCR in the control and IBA+NAA treatments. The results indicated that the response to exogenous auxins varied depending on the clone analyzed. In the clone A, the IBA+NAA combination showed the best results, increasing both adventitious root formation and root system development. In the clone B, no significant differences were found, although a positive trend was observed with the combined treatment. At the molecular level, an initial expression trend of TIR1 was observed after hormonal application. In conclusion, these findings highlight the relevance of auxins in the regulation of adventitious rooting and suggest that the combination of IBA and NAA could be a promising alternative for improving clonal propagation of Eucalyptus dunnii.