Poster: Plant insect-nematode interactions
Abs #
495: Russian wheat aphid-mediated elicitation of the wheat defense-tanscriptome.
Diuraphis noxia (Russian wheat aphid, RWA) is a pest on wheat in South Africa and many other wheat growing countries. Our previous studies on the intercellular washing fluid (IWF) of wheat cultivars resistant ('Tugela DN') and susceptible ('Tugela') to RWA showed alteration of some protein complexes within the first 12h after RWA infestation in the resistant cultivar, but not in the susceptible near isogenic line. Both induction and suppression of proteins were observed using chitinase-, ß-1,3-glucanase- and peroxidase activities, IEF and serological subunit composition, and 2-D-gel electrophoresis. Two responses, an initial hypersensitive response (HR) that decreases after approximately 24h, which is followed by systemic acquired resistance (SAR) that prevails in the tissue for an extended period of time, were observed. Many R genes from various plant species, including wheat encode conserved domains, particularly the nucleotide binding sites (NBS) and leucine rich repeat regions (LRR), consistent with their roles in signal transduction and protein-protein interactions. Wheat NBS-LRR homologs were obtained using degenerate primers sets designed from consensus NBS motifs derived from other genome studies (e.g. Arabidopsis and rice), subtraction suppression hybridisation (SSH), RACE-PCR and cDNA libraries. Transcript derived fragments were also obtained using cDNA-amplified fragment length polymorphism (AFLP) analysis. Selected clones were spotted onto microarrayer slides and analysed. Results indicated that wheat homologs to RGA-2 (GenBank accession # AF326781; 7e-13; NBS-RGA2) and chloroplast ATP synthase (GenBank accession # CB412200) are regulated in response to RWA feeding. Mapping studies confirmed the linkage of these transcripts to the RWA Dn1 resistance gene.
