FUNCTIONAL GENOMIC ANALYSIS OF SOYBEAN INTERACTIONS WITH PATHOGENIC AND NON-PATHOGENIC ISOLATES OF FUSARIUM OXYSPORUM

Fusarium oxysporum is one of the most common species causing soybean root rot and seedling blight in the U.S. In the present study, a RNA-seq-based analysis was used for the first time to investigate the molecular aspect of the interaction of a partially resistant soybean genotype with non-pathogenic/pathogenic isolates of F. oxysporum at 72 and 96 hours post inoculation (hpi). Markedly different gene expression profiles were observed in response to the two isolates. A peak of differentially expressed genes (DEGs) was observed at 72 hpi in soybean roots in response to both isolates, but the number of DEGs was about eight times higher for the pathogenic isolate compared to the non-pathogenic one. Furthermore, the magnitude of induction was much greater in response to the pathogenic isolate. This response included a stronger activation of defense-related genes, transcription factors, and genes involved in ethylene biosynthesis, secondary and sugar metabolism. In addition, 1130 fungal genes were differentially expressed between the F. oxysporum isolates in planta during the infection process. Interestingly, 10% of these genes encode plant cell-wall degrading enzymes, reactive oxygen species-related enzymes and fungal proteins involved in primary metabolic pathways. Such information may be useful in the development of new methods of broadening resistance of soybean to F. oxysporum, including the silencing of important fungal genes.