Developmental genes related to parthenogenesis revealed sinusoidal pattern of gene-expression in mustard aphid Lipaphis erysimi

Mustard aphid, Lipaphis erysimi (Kalt.) is a major insect pest of rapeseed-mustard group of crops. The economic importance of this has prompted fundamental research on it including gene expression and gene silencing studies. To identify key genes regulating parthenogenetic reproduction, gene-expression pattern of five developmental genes have been studied across three developmental stages namely, nymph, third instar and adult. All the five genes showed a constitutive basal level as well as significant up-or down-regulation over and above the basal level, across the developmental stages. While LeENDO, LeSTRN and LeFAS genes showed decrease in gene expression as the insect matures to parthenogenetic mother; and LeRNH and LeSNIV showed continuous increase in transcript level peaking in alate mother. Interestingly, all the genes followed a sinusoidal pattern of gene-expression either directly or inversely related to progression of developmental stages from newborn nymph to adult parthenogenetic mother in L. erysimi. In addition, a phylogenetic analysis of these genes revealed extent of resemblance and divergence of the gene sequences with their homologs from other insects including aphid species and pollinators.