In vitro establishment of shoot meristems of Ilex paraguariensis and identification of endophytic bacteria

Abstract

Yerba mate (Ilex paraguariensis A. St.-Hil.) is a species of great economic, social and environmental importance for the southern regions of Brazil, Uruguay and Argentina. Currently the most diverse products are obtained from mate leaves, including mate tea. The objective of this study was to establish shoot meristem cultures (meristematic dome and a few primordia) of elite clones and identify the endophytic bacteria present in the explants. We tested the effect of clones (F1, F2, A03 and A07), culture media (MS, 1/2MS, 1/4MS and WPM), cytokinins (kinetin, BA and 2iP), activated charcoal (1, 2 and 3 g L−1), and disinfecting agent (sodium hypochlorite and mercuric chloride) on in vitro establishment. F1 and F2 clones were the most responsive for shoot meristem in vitro culture. WPM medium supplemented with 8.8 µM 2iP, 0.2 µM NAA and 3 g L−1 activated charcoal was the most suitable for the in vitro establishment of the F1 clone. No phytotoxic effect of the disinfectant was observed and some meristems sprouted. The isolated endophytic bacterium was identified for the first time in yerba mate as Agrobacterium larrymoorei. To conclude, we were able to establish in vitro culture of yerba mate using meristems as explants but the tissues were not free of endophytic microorganisms which could interfere with explant response.