Transcriptome comparison of Arabidopsis and rice responses to fungal infection under different Fe availability periods.

Iron (Fe) is an essential nutrient for virtually all plants that modulate immune responses. However, whereas low and high Fe availalbility confers susceptibility to the fungus Colletotrichum higgisianum, the same conditions lead to rice tolerance to Magnaporthe oryzae. To better understand the systemic responses behind this antagonistic pattern, transcriptome profiling on fungal infected Arabidopsis and rice plants has been conducted. To consider the signaling component and avoid the interference of tissues experiencing necrosis, samples were conducted on aerial tissues 48h post-infection, when both pathogens remain in the biotrophic phase. Collectively, our data support that Arabidopsis employs a defence strategy based on glucosinolates and other secondary metabolites, whereas rice uses oxidative stress based mechanisms. A different usage of Fe pools during infection is also proposed. Overall design: Arabidopsis thaliana and Oryza sativa japonica were cultivated on semi-hydroponic conditions irrigated with 1/10 Hoagland media adapted for low (20 µM Fe-EDTA, -Fe), sufficient (20 µM Fe-EDTA, suf) and high (20 µM Fe-EDTA, +Fe) iron availability. Plants were either mock treated or infected by spraying with Colletotrichum higgisianum (Arabidopsis) or Magnaporthe oryzae (rice) suspensions at 10^6 and 10^5 spores/mL, respectively. Shoot samples were harvested 48h post-infection and used for RNA-Seq profiling.