Isolation and analysis of differentially expressed genes from peanut in response to challenge with Ralstonia solanacearum

Background: Bacterial wilt caused by Ralstonia solanacearum is the most devastating disease in peanut. Planting resistant peanut cultivars is deemed as the sole economically viable means for effective control of the disease. To understand the molecular mechanism underlying resistance and facilitate breeding process, differences in gene expression between seeds of Rihua 1 (a Virginia type peanut variety resistant to bacterial wilt) inoculated with the bacterial pathogen suspension (10(9) cfu ml-1) and seeds of the same cultivar treated with water (control), were studied using the GenefishingTM technology. Results: A total of 25 differentially expressed genes were isolated. Expression of genes encoding cyclophilin and ADP-ribosylation factor, respectively, were further studied by real time RT-PCR, and full length cDNAs of both genes were obtained by rapid amplification of cDNA ends. Conclusions: The study provided candidate genes potentially useful for breeding peanut cultivars with both high yield and bacterial wilt resistance, although confirmation of their functions through transgenic studies is still needed.

Identification of chilling-responsive transcripts in peanut (Arachis hypogaea L. )

To isolate differentially expressed peanut genes responsive to chilling, a suppression subtractive hybridization (SSH) cDNA library was constructed for a chilling tolerant peanut cultivar A4 with mRNAs extracted from the seeds imbibed at 2ºC and 15ºC, respectively, for 24 hrs. A total of 466 cDNA clones were sequenced, from which 193 unique transcripts (73 contigs and 120 singlets) were assembled. Of these unique transcripts, 132 (68.4 percent) were significantly similar to the sequences in GenBank non-redundant (nr) protein database, which belonged to diverse functional categories including metabolism, signal transduction, stress response, cell defense and transcriptional regulation. The remaining 61 (31.6 percent) showed no similarity to either hypothetical or known proteins. Six differentially expressed transcripts were further confirmed with real-time quantitative PCR (RT-qPCR).