ASEXUAL REPRODUCTIVE ADAPTATION TO SIMULATED CRETACEOUS CLIMATIC VARIABLES BY NORWAY SPRUCE CELLS IN-VITRO

Conifers rarely undergo asexual reproduction by parthenogenesis (haplo id or diploid). When cells of Finnish Norway spruce genotypes are grow n in a bioreactor under environmental conditions more typical of the M esozoic (high temperatures, carbon dioxide, and humidity, abundant foo d supply, etc.), the barriers to asexual reproduction are removed. Gen e(s) for apomixis are now expressed in cell suspensions of the rescued early embryo. A new population of diploid embryos is reconstituted fr om these cells by an apomeiotic and parthenogenetic process. This sign ifies that asexual gene expression is latent and suppressed under clim atic conditions at the current seed sources. Moreover, cells are rever ting to conservative ontogenetic strategies for adapting to atmosphere -biosphere variables that have seen conifers survive through ''bottle- neck'' selective regimes in the deep past. The control of culture para meters with bioreactors enables the experimental testing of genotypes in today's forests for their adaptive reproductive responses to critic al parameters in models for atmosphere-biosphere change. Environmental preconditions for reproductive fitness and survival from one generati on to the next apomictic population can now be explored under controll ed conditions. This enables a new study of experimental phylogenetics as a function of changes in atmosphere-biosphere models. Copyright (C) 1996 Elsevier Science Ltd