EVIDENCE FOR SLTA1 AS A SALT-SENSITIVE ALLELE OF THE ARGINASE GENE (AGAA) IN THE ASCOMYCETE ASPERGILLUS-NIDULANS

Strains of Aspergillus ninulans carrying the sltA1 mutation, conferrin g sensitivity to KCl and NaCl, also showed an arginine-sensitive pheno type 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 sensi tivity. Similarly, revertants to salt tolerance showed a loss of argin ine sensitivity as did sltA1 strains that were transformed with a cosm id carrying the putative sltA1(+) wild-type allele. In addition, argin ine sensitivity could be relieved by L-ornithine. It is suggested that sltA1 is a salt-sensitive allele of the arginase gene (agaA).