Germlings of Uromyces appendiculatus respond to topographical
stimuli and develop appressoria. During this period several genes are
expressed, one of which is Inf24. Germlings were microinjected
with a sense and antisense fragment of the ORF of Inf24. Sense
(Inf24-S), 5′-ATG AGT GCT TCA TCG CAG CAG CAG-3′ fragment
did not affect germling response to the topographical stimuli
and the developed appressoria. Microinjection of antisense (Inf24-RC),
5′-CTG CTG CTG CGA TGA AGC ACT CAT-3′ blocked
gene transcription and appressoria were rarely formed. Injection of Inf24-RC
into already formed appressoria did not inhibit
continued development of subsequent infection structures, e.g. penetration
peg, sub-stomatal vesicle.