Recent gene multiplication and evolution of a juvenile hormone esterase-related gene in a lepidopteran pest

Abstract

Juvenile hormone esterase (JHE) is a carboxylesterase that plays critical roles in regulating larval to adult transition by hydrolyzing the key developmental and reproductive hormone, juvenile hormone (JH). In the current work, we have cloned and sequenced a superfamily of juvenile hormone esterase related genes in Sesamia nonagrioides (JHERs). These seemed to have been recently multiplied from a common ancestral gene and consequently were inherited in the resulting populations as intron-less and intron-rich genes (loci). We sequenced three JHER genes (one intron-rich and two intron-less) and four cDNAs encoding for juvenile hormone esterase related sequences. Three cDNAs presented nucleotide deletions similar to alternative splicing events when compared with the introns of the intron-rich gene. The exons of the intron-rich gene were >98% identical with one of the intron-less gene and the homologous sequences of all the four cDNAs. Moreover, the second intron-less gene seemed to be almost identical with one of the four cDNAs. The fourth cDNA contained an extensive (in-frame) deletion inside its ORF. This mRNA seems to be encoded by another gene which's deletion was generated by homologous recombination. Interestingly, our data revealed differential expression patterns for the four cDNAs. This study provides an initial assessment of the diversity of JHER genes in a population of Sesamia and presents this species as an attractive model to study the diversification of JHE-like esterase genes and their functional consequences.