Resumo

DELGADILLO-DIAZ DE LEON, José Silvestre; MORALES-DOMINGUEZ, José Francisco; SANTOS-DIAZ, María del Socorro  e  PEREZ-MOLPHE-BALCH, Eugenio. In vitro propagation of mexican oaks (Quercus spp.). Polibotánica [online]. 2013, n.35, pp.85-97. ISSN 1405-2768.

In order to provide an alternative to conventional propagation, a protocol was developed for the in vitro multiplication of four Mexican species of Quercus, which are exploited to produce timber and coal and are nowadays threatened. Multiple shoot induction from zygotic embryos of Quercus castanea, Q. eduardii, Q. resinosa and Q. rugosa cultured on Murashige and Skoog medium supplemented with 6-benzylamino-purine (BA) or kinetin is described. Results showed that both cytokinins affected shoot regeneration, where BA exhibited highest efficiency. Higher shoot proliferation frequency was observed in Q. castanea and Q. eduardii (91.7%), giving an average of 6.3 and 6.5 shoots per explant on medium with 3.0 and 4.0 mg 1^-1 BA, respectively. For Q. resinosa, the best response was obtained with BA at 3.0 mg 1^-1 producing 3.8 shoots per explant. Finally, Q. rugosa yielded 3.6 shoots per explant with 1.0 mg 1^-1 BA. Shoots were excised from the seedlings and transferred to half-strength medium supplemented with 10.0 mg 1^-1 indole-3-butyric acid for two or five days, and then transfer to half-strength medium for rooting. Under these conditions, 100, 100, 66.7 and 83.3% of the shoots of Q. castanea, Q. eduardii, Q. resinosa, and Q. rugosa generated roots, respectively. Plantlets were successfully acclimated to soil in greenhouse conditions with survival frequencies of 80% for Q. castanea, 83.3% for Q. eduardii, 73.3% for Q. resinosa, and 70.0% for Q. rugosa. This in vitro propagation method can contribute to the production of plants for reforestation thus supporting the conservation and rational use of these species.

Palavras-chave : cotyledonary nodes; cytokinins; in vitro culture; micropropagation; Quercus.

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