Abstract

To study rice-blast fungusinteractions in planta under confocal laser scanning microscopy, the transformants Magnaporthe oryzae expressing enhanced green fluorescence protein (EGFP) and red fluorescence protein (Ds-red2) were used. Rice cultivars were inoculated with the transformants in the compatible (S) or incompatible (R) interactions. The conidia normally germinated and formed appressoria on rice leaves in both interactions, but the penetration in R-interaction was strongly inhibited. In S-interaction, invasive hyphae (IH) rapidly spread into the leaf sheath epidermal cells; 300-600 μm in length and 20-40 μm in depth at 48 hpi, 600-900 μm in length and 40-56 μm in depth at 72 hpi, respectively. In R-interaction, the growth of IH was limited in the attacked cell, and the cell was browned, granulated and clearly auto-fluorescenced under XXX nm light. Next, some aspects of induced resistance and accessibility at microscopic level were investigated. Pre-inoculation of rice leaf sheath with the incompatible M. oryzae XX hrs prior to the challenging significantly suppressed invasive growth of the compatible M. oryzae in XXXX. Strong auto-fluorescence on the cell wall together with hyper sensitive reaction (HR) were often observed in the cells after challengedwith the compatible M. oryzae, and moreover, RT-PCR revealed strong expression of PBZ1/PR10 gene in the resistance induced cells implying that resistance reaction was induced. This strong suppression was observed around 500 μm from the site of pre-inoculation with the incompatible M. oryzae, suggesting that the resistance is induced locally rather then systemically.. On the other hand, pre-inoculation with the compatible M. oryzae XX hrs prior to the challenging significantly suppressed resistance to the incompatible M. oryzae and allow to infect the cells. However this induced accessibility was limited only in the attacked or adjacent cells.