First report of Phytopythium vexans and Phytopythium litorale associated with root rot symptoms on red raspberry (Rubus idaeus)

Abstract

Twenty-two root samples from raspberry plants exhibiting symptoms consistent with Phytophthora infection, i.e. cane wilt, chlorotic leaves, and blackened roots, were collected from two farms in Perthshire, Scotland, in November 2021 (Fig. 1). Roots were rinsed with water, cut into 20 mm sections, transferred into 70% (v/v) ethanol for 10 seconds and dried on sterile filter paper. Five root sections per sample were aseptically transferred to Petri dishes containing CMA-PARP medium (Stewart et al., 2014), sealed and incubated in the dark at 18 • C.The hyphal tips of growing colonies were transferred onto fresh CMA-PARP. Five isolates were obtained, with two distinct morphotypes: one produced sub-globose, non-to semi-papillate sporangia, while the second produced globose and papillate sporangia (Fig. 2). Root material (c. 1-2 g per sample) was freeze-dried in 2 mL microfuge tubes prior to DNA extraction with a PowerSoil Pro Kit (Qiagen, Germany) as per the manufacturer's instructions. PCR was performed using the Phytophthora genus-specific primer pair YPh1F/YPh2R (Schena et al., 2008).The Phytophthora species P. idaei, P. ilicis and P. plurivora were detected in the samples but no isolates of these species were obtained from root samples. To determine the identity of the isolates, the ITS region was amplified and sequenced with ITS5 and ITS4 primers (White et al., 1990). BLAST analysis revealed one isolate with a 99.49% identityThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.