Evidence for sltA1 as a salt-sensitive allele of the arginase gene (agaA) in the ascomycete Aspergillus nidulans

Strains of Aspergillus nidulans carrying the sltA1 mutation, conferring sensitivity to KCl and NaCl, also showed an arginine-sensitive phenotype whereby concentrations of the L-amino acid at or above 10 mM were toxic to growth. Sexual progeny of a cross between a sltA1 mutant and a wild-type strain showed a co-segregation of salt and arginine sensitivity. Sim-ilarly, revertants to salt tolerance showed a loss of arginine sensitivity as did sltA1 strains that were transformed with a cosmid carrying the putative sltA1⁺ wild-type allele. In addition, arginine sensitivity could be relieved by L-ornithine. It is suggested that sltA1 is a salt-sensitive allele of the arginase gene (agaA).