Fig 2.

Trk1p and/or Hak1p supports growth of Neurospora on low-potassium medium. Three-day drop colonies, grown at 30°C, were used. Column headers designate the presence of the wild type (+) or the knockout (Δ) for each gene, in the order (left to right) TRK1, TRK2, HAK1; viz., the relevant genotype of strain {+++} is TRK1 TRK2 HAK1, that of strain {Δ++} is trk1Δ TRK2 HAK1, that of strain {++Δ} is TRK1 TRK2 hak1Δ, etc. The potassium channel TOK1 was wild type in panel A, but deleted in the right-hand column of panel B. Suspensions of conidia (7 μl at 10⁶ cells/ml) were pipetted onto agar plates containing K⁺-free Vogel's minimal medium plus KCl, as indicated, with 3% sorbose to enforce colonial morphology (see Materials and Methods). The bright, scabrous ring surrounding each robust colony represents profuse conidiophores.