Abstract

Three breeding populations were included as part of a strategy to improve drought tolerance of E. globulus: (A) open pollinated progenies with genetic ranking of cubic volume from a clonal seed orchard, (B) a population of 107 plus trees generated by mass selection of trees exposed to the drought conditions prevailing in the semiarid region of Chile, and (C) control pollinated progenies by intraspecific crosses between the B x A populations using a “one stop pollination” system. Micro propagation and rooting tests were carried out by somatic embryogenesis and organogenesis to make drought resistant clones available for operational multiplication in nurseries. “In vitro” protocols were developed to induce morphogenic responses and genetic transformation in adventitious buds and seeds of E. globulus. Traceability of superior genotypes was also made on the basis of molecular genetic markers and was physiologically evaluated in a greenhouse under water stress conditions to characterize their potential for drought resistance. It was possible to establish protocols through two pathways that allowed an appropriate transformation via Agrobacterium tumefaciens and that resulted in regeneration of two highly productive clones of E. globulus. Two morphogenic pathways were obtained indirectly from callus, one of these was from indirect somatic embryogenesis in seed explants, and the other pathway was by indirect organogenesis of adventitious buds in the explants. One of the objectives of the project was to evaluate the rhizogenic ability of clones of E. globulus and identify drought tolerant genotypes for propagation by conventional, operational rooting of cuttingsor mini cuttings and by using hydroponics. The results confirmed that E. globulus is a species with the low rate of adventitious rooting of stem cuttings reported for this species. The limited material available for evaluation (18 clones) did not allow us to identify individuals with a high average percentage of rooting. However, there are clones that in some particular assays exhibited a high rhizogenic response (up to 92%). The average rooting percentage obtained in all trials reached 14.2% but great variability was observed in the trials. However, some clones reached a high percentages of rooting. Among them are clones 87, 48, 62, 82 and 77 that obtained values ranging between 60 and 93%. Such percentages are compatible with operational cloning of these individuals.