Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2011
Publication Date: 8/1/2011
Publication URL: http://hdl.handle.net/10113/500778
Citation: Radwan, O., Liu, Y., Clough, S.J. 2011. Transcriptional analysis of soybean roots response to Fusarium virguliforme, the causal agent of sudden death syndrome. Molecular Plant-Microbe Interactions. 24:958-972. Interpretive Summary: Sudden Death Syndrome (SDS) is a disease of soybean that is a constant threat to growers as it appears late in the season with little warning, and by the time symptoms appear, there is virtually nothing a grower can do but watch and hope it is not too severe. Complete genetic resistance does not exist for SDS so breeders have to rely on plants with partial resistance. Identifying the genes that produce this partial resistance is not easy because many genes are involved and each gene only has a small effect. We used a combination of gene expression analysis, mapping and identification of possible regulatory small RNA molecules to identify candidate defense-related genes. This information can be used by breeders to design new markers and determine more precisely the regions of the genome that may provide additional resistance to SDS.
Technical Abstract: Sudden death syndrome (SDS) of soybean can be caused by any of four distinct Fusarium species, with F. virguliforme and F. tucumaniae being the main casual agents in North and South America, respectively. Although the fungal tissue is largely confined to the root, the fungus releases a toxin that is translocated to leaf tissues where it causes interveinal chlorosis and necrosis leading to the scorching effect and possible defoliation. In this study, we report on an Affymetrix analysis measuring transcript abundances in resistant (PI 567374) and susceptible (Essex) roots upon infection by F. virguliforme, 5 and 7 days post infection. Many of the up regulated genes were common between resistant and susceptible plants (including genes related to the phenylpropanoid pathway, defense, signal transduction, and transcription factors) but some genotype-specific expression was noted. The transcript levels of many induced genes were induced to a greater degree in the susceptible plants. Changes in smRNA levels between inoculated and mock treated samples were also studied and implicate a role for these molecules in this interaction. In total, 2,467 genes were significantly changing in the experiment, with 1,694 changing in response to the pathogen; 93 small RNA and 88 miRNA were identified from infected tissue that have putative soybean gene targets. Comparing genotypes, 245 genes were uniquely modulating in the reistant host, whereas 378 genes were uniquely modulating in the susceptible host.