First confirmed report of the leaf rust Puccinia dichondrae on Dichondra repens in Italy

Dichondra repens (dichondra or kidney weed), family Convolvulaceae, is a low-growing perennial plant native to Australia and New Zealand. Increasingly it is used as a low maintenance cover plant in parks and gardens in the milder climatic regions of Italy. From 2004 to 2008, telia of a rust fungus were observed on the lower leaf surfaces of D. repens in gardens along the Tirrenian coast of central Italy: Marina di Massa, Torre del Lago, Pisa, Cecina and Rome. Infected plants had erect petioles with leaves that were curled and folded along the mid-rib so that the lower surfaces were fully exposed (Fig. 1). Yellowing associated with telia was seen in rare cases on the upper foliar surface. Telia were dark brown, becoming erumpent, 89.3-155.1 (115.8) µm. Teliospores (Fig. 2) were brownish-yellow, two-celled, with smooth cell walls, constricted at the septum, having a conical papilla on the upper cell, 9.4-18.8 x 18.8-37.6 (14.2 x 30.24) µm. Each teliospore had a broken, colourless, filiform pedicel, 7.05-23.5 (13.86) µm long.Based on the host and the morphological characteristics this rust pathogen was identified as Puccinia dichondrae apud Saccardo (Saccardo, 1888).A detailed taxonomic discussion of the fungus is available in Hennen et al. (2005).

The ITS region was amplified using primers ITS5/ITS4, as described by Weber et al. (2003). The ITS sequence was deposited in EMBL database (Accession No. FN298146). As this was the first sequence deposited for P. dichondrae, comparison was performed with other Puccinia spp. and resulted in high homology. This pathogen was first described in Chile on Dichondra repens and D. sericeae. It has since been recorded from Argentina to the USA, South Africa, Australia and New Zealand on D. repens , D. sericeae, D. brevifolia, D. micrantha and Dichondra sp. (Hennen et al., 2005; Mckenzie, 1998; Saccardo, 1888). Cardin et al. (2005) reported a Puccinia sp. on D. repens in France and Italy, but did not make reference to the species. This is therefore the first confirmed report of P. dichondrae from Italy and Europe.