FIRST REPORT OF ITERSONILIA PERPLEXANS ON ANETHUM GRAVEOLENS IN ITALY

Abstract

In Apulia (southern Italy), dill (Anethum graveolens) is cultivated in a few greenhouses and fields, mainly located between Bari and Brindisi. In December-January of 2010 to 2014, leaf blight was observed in greenhouse-grown dill crops, when they were near the harvest stage. Symptoms differed from those induced by some known foliar pathogens of dill, i.e. Sclerotinia sclerotiorum and Erysiphe heraclei, but recalled those caused by Botrytis cinerea. In fact, leaves that were first discolored, turned light to dark brown, and finally wilted, rendering the affected plants unsuitable for harvest. In the presence of high relative humidity, a whitish-cream mycelium developed on symptomatic leaves. Light microscope observations revealed the presence of hyaline hyphae with clamp connections and lunate ballistospores [16.4 ± 1.7 (standard deviation) × 11.0 ± 1.3 μm]. A 609 bp product amplified by PCR from fungal DNA using the ITS1/ITS4 primer pair was sequenced (BMR Genomics, Italy) and the sequence of an isolate designated IPSP-GB520 was deposited in GenBank under the accession No. KP890654. BLAST alignment revealed a 99% homology at the nucleotide level with several accessions of Itersonilia perplexans Derx (Basidiomycota, Cystofilobasidiaceae), including two isolates (DQ667163 and NR_077117) conserved at the CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands. Koch’s postulates were fulfilled with a successful detachedleaf assay. Based on morphological characteristics and nucleotide sequence homology, the fungus was identified as I. perplexans. In Italy, an early report ascribed leaf blight of dill to I. pastinacae, based on morphometric observations and pathogenicity tests (Matta and Garibaldi, 1968). To the best of my knowledge, this is the first report of I. perplexans on dill in Italy.