To investigate the function of schetR gene in a non-heterocystous cyanobacterium,Schizothrix calcicola,the schetR over-expression vector driven by strong promoter petE was constructed and transformed into hetR mutant in model strain Anabaena PCC 7120.The results showed that the over-expression of schetR could complement the phenotype of Anabaena hetR mutant.This indicates that schetR performs a function of stimulating heterocyst development.