Interactions between isolates of Puccinia smyrnii, an autoecious, demicyclic rust and accessions of Smyrnium olusatrum

Abstract

Plants derived from bulked seed samples of Smyrnium olusatrum collected from small patches of plants in Anglesey, Gwynedd, Shropshire and Suffolk were all susceptible, but expressed quantitative differences in disease severity, when inoculated with either aeciospores or teliospores of Puccinia smyrnii from the same or similar locations under controlled environmental conditions. Latent periods (mean 16 and 11 days for appearance of telia and spermagonia, respectively) were longer in 1996 compared with repeat inoculation in 1997 when the rust was more severe. Summation of mean numbers for each year of both aecia and telia, for rust isolate x host accession combinations, showed significantly different numbers of aecia in both years but not of telia. Incidence and severity of P. smyrnii varied on plants derived from seed from Anglesey, Shropshire and Suffolk when transplanted into a naturally rust-affected population of S. olusatrum at Gwynedd, but all plants were susceptible. Experimental transfer of spermatia between spermagonia confirmed that P. smyrnii is heterothallic.