Description:
The Russian wheat aphid (Diuraphis noxia) (RWA) is a particularly noxious pest of wheat. Our objective is to find virulent genes in RWA. Our work is guided by studies in the pea aphid, Acyrthosiphon pisum, a model aphid for which the genome project is nearing completion. Seventeen transcripts were selected for investigation from the salivary gland of Biotypes 1 and 2 of the RWA. Using RT‐PCR primers based either directly on pea aphid cDNA sequences or on a range of orthologous sequences from insect species, we have amplified and cloned regions of these 17 transcripts. We will present a summary of the results, which vary widely from transcript to transcript. Examples are transcripts for C002, trehalase and sucrase. For that encoding protein C002, which has been shown in the pea aphid to be required for feeding on a host plant, we have found 9 different haplotypes, 8 of which are apparently unique to either Biotype 1 or 2. For transcripts putatively encoding the enzyme trehalase, we have found 8 different haplotypes, 7 of which are unique to one biotype or the other. For transcripts putatively encoding the enzyme sucrase, we have found 15 different haplotypes, 8 unique to Biotype 1 and 6 unique to Biotype 2. In conclusion high level of genetic diversity in salivary gland transcripts are observed between biotypes 1 and 2 of RWA, which correlates molecular variation in salivary gland proteins with the virulence phenotype.Supported by CRC, Australia.