Peronospora sparsaon CultivatedRubus arcticusand Its Detection by PCR Based on ITS Sequences

Abstract

In 1994 to 1996, large yield losses were reported in cultivated arctic bramble (Rubus arcticus) due to berries drying in the middle of the growing season in the entire cultivation area (62° to 66° N) in Finland. Interveinal, angular, purple-red lesions on leaves are associated with the dryberry disease. Cultivations of arctic bramble were inspected in 1995 and 1996, and 69 plant samples and 137 rootstocks were collected and examined for fungi in the laboratory. Perono-spora sparsa was the species most commonly found in all types of samples tested, but Fusarium avenaceum, Cylindrocarpon destructans, and Botrytis cinerea also were detected. P. sparsa was shown to overwinter in the underground parts of arctic bramble. Laboratory tests showed that the two main cultivars of arctic bramble (Pima and Mespi) were susceptible to P. sparsa. Sequences of the internal transcribed spacer (ITS) regions 1 and 2 of the rDNA genes were determined in four and six isolates, respectively, of P. sparsa, and little sequence variability was detected. The corresponding ITS regions of arctic bramble, the above mentioned fungi, a Phoma sp. previously isolated from arctic bramble, and Phytophthora cactorum isolated from strawberry were also determined and compared with the corresponding sequences of P. sparsa. Subsequently, two pairs of primers were designed to the ITS regions that could be used to detect either P. sparsa and Phytophthora cactorum, or only P. sparsa, respectively, by polymerase chain reaction (PCR) using two different types of thermal cyclers (“heated block” Mini Cycler and “hot air flow” Rapid Cycler).

A Comparison of Peronospora parasitica (Downy Mildew) Isolates from Arabidopsis thaliana and Brassica oleracea Using Amplified Fragment Length Polymorphism and Internal Transcribed Spacer 1 Sequence Analyses

“…The ITS1 sequence of A. candida (At) isolates showed high homology with the ITS1 sequence of an A. candida isolate from Lepidium campestre (Jacobson et al, 1998). BLASTN homology searches using the ITS1 sequences of P. parasitica (At), P. parasitica (Bo), and B. lactucae isolates detected homology with P. sparsa (Rubus arcticus) (Lindqvist et al, 1998) and numerous Phytophthora species. Eleven ITS1 sequences, including the 5 sequences from this work and 6 previously published sequences, were aligned and used to construct a phylogenetic tree (Fig.…”

“…An unrooted phylogenetic tree produced from an alignment of ITS1 sequences of Peronosporales isolates P. destructor (unknown host) (unpublished; GenBank Accession No. AB021712), P. sparsa (Ra) (Lindqvist et al, 1998), Ph. gonapodyides (Qr) , Ph.…”

Quantification of downy mildew (Peronospora sparsa) in Rubus species using real-time PCR

“…P. rubi) causes downy mildew disease in Rubus and Rosa species (Hall, 1989;Breese et al, 1994), resulting in the ÔdryberryÕ disease and severe yield losses in Rubus plants such as blackberry (Rubus fruticosus), boysenberry (Rubus spp. hybrid) and arctic bramble (Rubus arcticus subspecies arcticus) (Tate, 1981;McKeown, 1988;Hall, 1989;Lindqvist et al, 1998).…”

“…by the liqueur industry because of their unique aroma. However, the cultivation areas have remained small because of P. sparsa infections, which cause high annual fluctuations in the yield (Lindqvist et al, 1998;Kokko et al, 1999). The symptoms are the reddish, angular and interveinal lesions on the leaves, conidiophores on the abaxial surface of the leaves and, later during the season, dry berries, which occasionally become malformed.…”

Specific primers for the differentiation of Heterobasidion annosum (s.str.) and H. parviporum infected stumps in northern Europe

“…The methods may be based on Internal Transcribed Spacer (Lindqvist et al 1998), ribosomal RNA genes (Edel et al 2000) or other DNA (Paavolainen et al 2000). In this report we describe the development and testing of a PCR based tool for the identifi cation of H. annosum and H. parviporum.…”