Indução e caracterização morfoanatômica de calos e suspensão celular de Eucalipto

Abstract

Eucalyptus is a woody plant with major applicability in the timber, cellulose and paper industries and even in the pharmaceutical industry with the production of essential oils. However, eucalyptus has a high level of heterozygosity, which hinders the conventional breeding processes. Although the genetic transformation of plants is a potential technology to assist conventional techniques of genetic improvement, for perennial species, this methodology remains difficult to be adopted due to the absence of an effective regeneration system for transformed plants. In this context, one of the potential strategies used in tissue culture is somatic embryogenesis, which added to the cultivation of cell suspension, can bring benefits when applied to the culture of woody species, which includes eucalyptus. This approach brings advantages, as for instance, mass clonal propagation in a short period of time and also assist in obtaining cultivars with qualities of interest. Nevertheless, one of the difficulties faced by recalcitrant species such as eucalyptus is the low efficiency of inducing callogenesis and the low frequency of germination of embryos, making its application limited. Therefore, the goal of this work was to test the culture media MS and modified MS with its NH 4 NO 3 reduced up to 50% of its concentration, adding cytokinins (BAP, KN and 2-iP) to the culture. N6, MS and JADS media were also tested with the addition of picloram (0, 100, 200, 400 and 800 M) in order to induce embryogenic calluses and to obtain an efficient protocol for eucalyptus cell suspension and regeneration of the respective somatic embryos. The results showed that the reduction of ammonium nitrate in the culture medium did not seem to favor the induction of callus formation in E. grandis. The use of 2-iP helped in the formation of semi-friable yellow calluses, and the use of BAP favored the formation of compact yellow calluses. Calli originated from hypocotyl and leaf, that were cultivated in N6 and JADS medium showed potential for obtaining somatic embryogenesis.