Complementation cloning of salt tolerance determinants from the marine hyphomycete Dendryphiella salina in Aspergillus nidulans

A preliminary physiological characterization of osmoregulation in an Asperg illus nidulans salt sensitive mutant carrying cotransformed DNA sequences f rom the marine hyphomycete Dendryphiella salina is described. A genomic DNA library made in lambda EMBL3 was cotransformed with the plasmid pDJB3 into an A. nidulans host carrying a selectable marker for transformation (pyrG8 9) and a salt sensitivity mutation (sltA1). In some cases D. salina clones appeared to directly complement the salt sensitivity mutation by restoring salt and arginine insensitivity. Other clones gave marked increases in salt tolerance and yet the hosts remained arginine sensitive. Improvements in s alt tolerance correlated with an enhanced ability to induce polyol biosynth esis during salt challenge.