Figure 4.

Northern-blot analysis of POTLX-3 mRNA accumulation in response to P. infestans inoculation. Detached leaflets of cv Kennebec (resistance gene R-1) were inoculated with a sporangial suspension of P. infestans US940507 (US1), incompatible interaction resulting in resistance (A), or with ME93-2A (US8), compatible interaction (B). cv Superior leaflets were inoculated with P. infestans ME93-2A, compatible interaction that resulted in susceptibility (C). Total RNA was extracted from inoculated leaflets that were incubated in a growth chamber at 18°C for the indicated times. An equal amount of total RNA (18 μg per lane) was loaded in each lane and transferred onto a nylon membrane. The blots were hybridized with the ³²P-labeled 1.5-kb EcoRI fragment of the POTLX-3 cDNA clone. The blots were stripped and rehybridized to a 1.2-kb wheat 18S ribosomal RNA probe (D) to confirm that similar quantities of total RNA were present in each lane.