Austrocedrus chilensis (Patagonian cypress) is an endemic tree in the Cupressaceae, found in southern Argentina and Chile. In Argentina, it grows in a 60 to 80 km wide strip along the Andean foothills across a broad moisture gradient, in a variety of ecological niches. In the west, cypress can be found either in mixed stands with Nothofagus spp. or in pure stands. In the north, it can be found mixed with Araucaria araucana. It also grows in open, xeric forests or in isolated clumps at the limit of the Andean foresst getting into the steppe, preventing desert advance. Cypress is valued not only because of its ecological function but because of the quality of its wood. Phytophthora austrocedri is a soil pathogen that causes severe mortality of the species. Mortality was first registered in 1948 and its cause remained unknown for 60 years, which led the species to a serious threat of conservation. Individuals with different degrees of susceptibility to the pathogen are generally observed in affected areas. Since factors associated with the spread of the disease are difficult to control, detection and asexual propagation of tolerant/resistant individuals is the best solution to the problem. At present, little work with no success regarding vegetative micropropagation of the cypress was done. The aim of this study was to contribute to the development of a micropropagation protocol. Seeds were collected from open pollinated natural stands. Before sowing, seeds were pre-chilled for 45 days. Germinated seeds were submerged in 25% sodium hypochlorite solution for 10 min and then transferred to 70% ethanol for a min, for seedlings disinfection.
Cotyledons and adult leaves were used as material for explants, and three basal initiation media were tested: modified LP, WP and MS. Media were supplemented with 2,4-Dichlorophenoxyacetc acid (22,6μM), sucrose (30 g•l-1) and Bacto agar (8 g•l-1), pH was adjusted to 5,7 before autoclaving. Incubations were performed in the darkness in a growth chamber at 24±2°C.
Green to translucid, or white, calluses, were first observed after 20 days in all assayed media.
This preliminary study evidenced that A. chilensis might be able to be propagated by indirect organogenesis or somatic embryogenesis, which will allow to address its application in conservation and restoration programs, as well as in capturing genetic gain from elite genotypes for production purposes. However, more studies are needed to get insight and optimize the process.