Sequence comparison of aflR from different Aspergillus species provides evidence for variability in regulation of aflatoxin production

Transposon mutagenesis has provided one of the first and most important routes to gene identification and characterization. In the 17 years since the bz1 gene was first tagged with Activator (Ac), more than 60 genes involved in plant development have been cloned using elements such as Supressor-mutator (Spm) and Mutator (Mu) from maize and Tag1 from Arabidopsis. The advantages of transposon-induced alleles in the study of developmental processes go beyond cloning to include sector analysis, generation of new alleles, and conditional expression based on suppression. The laborious technique of directed tagging that led to many of these successes is now being supplanted by systematic projects to produce large collections of transposon insertions that are precharacterized using PCR-based methods and publicly accessible for both forward and reverse genetics. Of the tens of thousands of new genes postulated to exist in Arabidopsis and other species, most are turning out to have no obvious phenotypic effect. The challenge for functional genomics is now to elucidate the apparently subtle actions of genes at a rate commensurate with their discovery