A pathogen of New Zealand Pyropia plicata (Bangiales, Rhodophyta), Pythium porphyrae (Oomycota)

Abstract

Geographic distributions of pathogens are affected by dynamic processes involving host susceptibility, availability and abundance. An oomycete, Pythium porphyrae, is the causative agent of red rot disease, which plagues Pyropia farms in Korea and Japan almost every year and causes serious economic damage. We isolated an oomycete pathogen infecting Pyropia plicata from a natural population in Wellington, New Zealand. The pathogen was identified as Pythium porphyrae using cytochrome oxidase subunit 1 and internal transcribed spacer of the rDNA cistron molecular markers. Susceptibility test showed that this Pythium from New Zealand was able to infect several different species and genera of Bangiales including Pyropia but is not able to infect their sporophytic (conchocelis) phases. The sequences of the isolated New Zealand strain were also identical to Pythium chondricola from Korea and the type strain from the Netherlands. Genetic species delimitation analyses found no support for separating P. porphyrae from P. chondricola, nor do we find morphological characters to distinguish them. We propose that Pythium chondricola be placed in synonymy with P. porphyrae. It appears that the pathogen of Pyropia, both in aquaculture in the northern hemisphere and in natural populations in the southern hemisphere is one species.

Isolation and characterization of two phototropins in the freshwater green alga, Spirogyra varians (Streptophyta, Zygnematales)

“…The tree was generated using these amino acid sequences with Bayesian phylogenetic analysis (MrBayes 3.2.6) (Huelsenbeck and Ronquist 2001) using a Blosum substitution model, 2,000,000 generations, subsampling frequency every 400 generations, and a burn-in length of 200,000 generations. Maximum likelihood analysis used RAxML 7.2.8 (Stamatakis 2014) using a WAG + gamma model with a method described previously (Diehl et al 2017). Bootstrap support values (%) ans first strand cDNA using the DIG probe Synthesis Kit (Roche Diagnostics, Berlin, Germany).…”

Compositional Shifts of Bacterial Communities Associated With Pyropia yezoensis and Surrounding Seawater Co-occurring With Red Rot Disease

“…Red rot disease has been reported as one of the major constraints in the profitable cultivation of Pyropia in China, Korea, and Japan, and no effective measurements have been developed to control the disease (Kim et al, 2014). Members of two species within the oomycetic genus Pythium ( P. porphyrae and P. chondricola ) are frequently reported as the causative agents of this disease (Lee et al, 2015, 2017; Diehl et al, 2017), although isolate of Alternaria is also capable of causing red rot disease (Mo et al, 2016). The pathogen Pythium can survive in both sea farms and terrestrial runoffs, even in the off-season, both of which could be the source of the zoospore inoculum initiating red-rot disease in farms (Ding and Ma, 2005; Kim et al, 2014; Klochkova et al, 2017).…”

Red And far‐red regulation of filament movement correlates with the expression of phytochrome and FHY1 genes in Spirogyra varians (Zygnematales, Streptophyta)1

“…The Micromonas pusilla PHY was used as an outgroup. Maximum likelihood analysis used RAxML 7.2.8 (Stamatakis 2014) using a LG + gamma model as described previously (Diehl et al 2017). Bootstrap support values (%) were calculated based on 1,000 replicates.…”