Microinjected antisense Inf24 oligonucleotides inhibit appressorium development in Uromyces

Germlings of Uromyces appendiculatus respond to topographical stimuli and develop appressoria. During this period several genes are expressed, one of which is Inf 24. Germlings were microinjected with a sense and antisense fragment of the ORF of Inf 24. Sense ( Inf 24-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 ( Inf 24-RC), 5′-CTG CTG CTG CGA TGA AGC ACT CAT-3′ blocked gene transcription and appressoria were rarely formed. Injection of Inf 24-RC into already formed appressoria did not inhibit continued development of subsequent infection structures, e.g. penetration peg, sub-stomatal vesicle.