OSMOTICALLY-STRESSED POPLAR CELL-CULTURES - ANTHOCYANIN ACCUMULATION,DEAMINASE ACTIVITY, AND SOLUTE COMPOSITION

Anthocyanin accumulated in mannitol-stressed cell suspensions of popla r [Populus deltoides (Marsh) Bartr, var. occidentalis (Rydb.)] in cult ure. Both phenylalanine ammonia lyase (PAL, EC 4.3.1.5) and tyrosine a mmonia lyase (TAL, EC 4.3.1) activities increased in the stressed cell s, but PAL activity was up to 9 times higher than that of TAL. Two sep arate enzymes were found, and the increased PAL activity of the osmoti cally-stressed cells was correlated with increased levels of PAL prote in. Greater contents of organic solutes accumulated in the stressed ce lls compared to control cells. Of the amino acids, higher contents of alanine, glutamine, glutamate, asparagine, and serine were present in the stressed cells. Although the organic acid content of the cells dec lined in culture, stressed cells contained higher concentrations. The soluble carbohydrate content of the stressed cells was higher, not onl y due to the uptake of mannitol, but also due to sucrose, and inositol to a lesser extent. AU of these organic compounds could act colligati vely in osmotic-stress adjustment, and some of them could influence th e activity of the deaminating enzymes.