Appressorium differentiation and penetration in M. oryzae Δmet6 mutants.

Spores of wild type P1.2, Δmet6 mutants (M15.1, M22.1, M23.1) and ectopic P1.2 transformant E19.1 were deposited on a Teflon membrane with hexadecanediol or on detached barley leaves kept on kinetin water agar plates. Spore germination and appressorium formation were observed using a bright field microscope. Epidermal layer was stripped 24–30 h after inoculation. Appressoria formed on barley leaves were stained with Cotton blue in lactic acid and observed using a bright field microscope. Penetration was scored as successful if unstained infectious hyphae were detected inside epidermal cells underneath appressoria (Fig 7). Δmet6 mutants differentiated appressoria at normal rate that were unable to penetrate into plant epidermal cells. na*: not analyzedAppressorium differentiation and penetration in M. oryzae Δmet6 mutants.