Project description:Some Pyropia species, such as nori (P. yezoensis), are important marine crops. We conducted a phylogenetic analysis of 39 samples of Pyropia species grown in Japan using organellar genome sequences. A comparison of the chloroplast DNA sequences with those from China showed a clear genetic separation between Japanese and Chinese P. yezoensis. Conversely, comparing the mitochondrial DNA sequences did not separate Japanese and Chinese P. yezoensis. Analysis of organellar genomes showed that the genetic diversity of Japanese P. yezoensis used in this study is lower than that of Chinese wild P. yezoensis. To analyze the genetic relationships between samples of Japanese Pyropia, we used whole-genome resequencing to analyze their nuclear genomes. In the offspring resulting from cross-breeding between P. yezoensis and P. tenera, nearly 90% of the genotypes analyzed by mapping were explained by the presence of different chromosomes originating from two different parental species. Although the genetic diversity of Japanese P. yezoensis is low, analysis of nuclear genomes genetically separated each sample. Samples isolated from the sea were often genetically similar to those being farmed. Study of genetic heterogeneity of samples within a single aquaculture strain of P. yezoensis showed that samples were divided into two groups and the samples with frequent abnormal budding formed a single, genetically similar group. The results of this study will be useful for breeding and the conservation of Pyropia species.
Project description:<h4>Background</h4>Pyropia haitanensis and P. yezoensis are two economically important marine crops that are also considered to be research models to study the physiological ecology of intertidal seaweed communities, evolutionary biology of plastids, and the origins of sexual reproduction. This plastid genome information will facilitate study of breeding, population genetics and phylogenetics.<h4>Principal findings</h4>We have fully sequenced using next-generation sequencing the circular plastid genomes of P. hatanensis (195,597 bp) and P. yezoensis (191,975 bp), the largest of all the plastid genomes of the red lineage sequenced to date. Organization and gene contents of the two plastids were similar, with 211-213 protein-coding genes (including 29-31 unknown-function ORFs), 37 tRNA genes, and 6 ribosomal RNA genes, suggesting a largest coding capacity in the red lineage. In each genome, 14 protein genes overlapped and no interrupted genes were found, indicating a high degree of genomic condensation. Pyropia maintain an ancient gene content and conserved gene clusters in their plastid genomes, containing nearly complete repertoires of the plastid genes known in photosynthetic eukaryotes. Similarity analysis based on the whole plastid genome sequences showed the distance between P. haitanensis and P. yezoensis (0.146) was much smaller than that of Porphyra purpurea and P. haitanensis (0.250), and P. yezoensis (0.251); this supports re-grouping the two species in a resurrected genus Pyropia while maintaining P. purpurea in genus Porphyra. Phylogenetic analysis supports a sister relationship between Bangiophyceae and Florideophyceae, though precise phylogenetic relationships between multicellular red alage and chromists were not fully resolved.<h4>Conclusions</h4>These results indicate that Pyropia have compact plastid genomes. Large coding capacity and long intergenic regions contribute to the size of the largest plastid genomes reported for the red lineage. Possessing the largest coding capacity and ancient gene content yet found reveal that Pyropia are more primitive multicellular red algae.
Project description:<i>Pyropia pulchra</i> (Hollenberg) S.C. Lindstrom & Hughey is a foliose seaweed in Bangiales order distributed in North America. We assembled the complete mitochondrial genome sequence of <i>Pyropia pulchra</i> (33,190 bp), and annotated 26 protein-coding genes, 24 transfer RNAs, and 2 ribosomal RNAs. We analyzed a maximum likelihood tree using conserved 23 mitochondrial genes from Bangiales species. The mitochondrial phylogeny of Bangiales species shows a strong monophyletic relationship of genus <i>Pyropia</i>, and the taxonomic position of <i>P. pulchra</i> within the genus.
Project description:A commonly found red alga of the upper intertidal zone of New Zealand rocky coasts is described for the first time as Pyropia plicata sp. nov. This species has been incorrectly known as Porphyra columbina Mont. (now Pyropia columbina (Mont.) W.A.Nelson) for many years. Pyropia plicata is widespread and common, and it is readily distinguished from other species of bladed Bangiales in New Zealand by its distinctive morphology, with pleated blades attached by a central rhizoidal holdfast.
Project description:The present study utilizes polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis using partial plastid rbcL and mitochondrial trnC-trnP gene sequences to distinguish the six representative Pyropia species produced via mariculture in Korea. The rbcL, trnC, and trnP sequences of 15 Pyropia species from the NCBI database were aligned to determine specific restriction enzyme sites of the six Pyropia species. To confirm the presence of restriction sites of eight enzymes, PCR amplicons were digested as follows: a 556 bp fragment within the rbcL region of chloroplast DNA was confirmed in P. yezoensis using BglI, whereas Tth111I, AvaII, BsrI, and BsaAI enzymes produced fragments of 664, 271, 600, and 510 bp, respectively, from the rps11-trnG region of mitochondrial DNA in P. seriata, P. dentata, P. suborbiculata, and P. haitanensis. In the case of P. pseudolinearis, HindIII, SacII, and SphI enzymes each had two cleavage sites, at positions 174 and 825, 788 and 211, and 397 and 602 bp, respectively. All six species were successfully distinguished using these eight restriction enzymes. Therefore, we propose that PCR-RFLP analysis is an efficient tool for the potential use of distinguishing between the six Pyropia species cultivated via mariculture in Korea.
Project description:P. yezoensis is an economically important marine crop and highly used seafood in China containing a high number of proteiP. yezoensis is an economically important marine crop and highly used seafood in China containing a high number of proteins. An oomycete, known as Pythium porphyrae, causes the red rot disease that seriously damages Pyropia farms every year in China, Korea, and Japan. To investigate the pathogen responsive proteins after the artificial infection of Pyropia with (P. porphyrae) oomycetes spores, an iTRAQ-based proteomic analysis was performed. A total of 762 differentially expressed proteins (DEP’s) were identified from which 378 proteins were highly expressed and 284 proteins were found to be low expressed. A large number of differentially expressed proteins were identified, which are involved in disease stress, carbohydrate metabolism, photosynthetic activity, and amino acid pathways as annotated in the Kyoto Encyclopedia of Genes and Genomes KEGG database. Our results showed that Pyropia resisted infection by inhibiting photosynthesis, energy and carbohydrate metabolism pathways, as supported by the change in the expression level of related proteins. Thus, the current research data provide an overall summary of the red algae response to pathogen infection. The present study could assist in a better understanding of the mechanisms behind infection resistance in P. yezoensis as well as improve the breeding of Pythium infection tolerant macroalgaens. An oomycete, known as Pythium porphyrae, causes the red rot disease that seriously damages Pyropia farms every year in China, Korea, and Japan. To investigate the pathogen responsive proteins after the artificial infection of Pyropia with (P. porphyrae) oomycetes spores, an iTRAQ-based proteomic analysis was performed. A total of 762 differentially expressed proteins (DEP’s) were identified from which 378 proteins were highly expressed and 284 proteins were found to be low expressed. A large number of differentially expressed proteins were identified, which are involved in disease stress, carbohydrate metabolism, photosynthetic activity, and amino acid pathways as annotated in the Kyoto Encyclopedia of Genes and Genomes KEGG database. Our results showed that Pyropia resisted infection by inhibiting photosynthesis, energy and carbohydrate metabolism pathways, as supported by the change in the expression level of related proteins. Thus, the current research data provide an overall summary of the red algae response to pathogen infection. The present study could assist in a better understanding of the mechanisms behind infection resistance in P. yezoensis as well as improve the breeding of Pythium infection tolerant macroalgae
Project description:Pyropia haitanensis (Bangiales, Rhodophyta), a major economically important marine crop, is also considered as an ideal research model of Rhodophyta to address several major biological questions such as sexual reproduction and adaptation to intertidal abiotic stresses. However, comparative genomic analysis to decipher the underlying molecular mechanisms is hindered by the lack of high-quality genome information. Therefore, we integrated sequencing data from Illumina short-read sequencing, PacBio single-molecule sequencing and BioNano optical genome mapping. The assembled genome was approximately 53.3 Mb with an average GC% of 67.9%. The contig N50 and scaffold N50 were 510.3 kb and 5.8 Mb, respectively. Additionally, 10 superscaffolds representing 80.9% of the total assembly (42.7 Mb) were anchored and orientated to the 5 linkage groups based on markers and genetic distance; this outcome is consistent with the karyotype of five chromosomes (n = 5) based on cytological observation in P. haitanensis. Approximately 9.6% and 14.6% of the genomic region were interspersed repeat and tandem repeat elements, respectively. Based on full-length transcriptome data generated by PacBio, 10,903 protein-coding genes were identified. The construction of a genome-wide phylogenetic tree demonstrated that the divergence time of P. haitanensis and Porphyra umbilicalis was ~204.4 Ma. Interspecies comparison revealed that 493 gene families were expanded and that 449 were contracted in the P. haitanensis genome compared with those in the Po. umbilicalis genome. The genome identified is of great value for further research on the genome evolution of red algae and genetic adaptation to intertidal stresses.
Project description:Disease outbreaks devastate Pyropia aquaculture farms every year. The three most common and serious diseases are Olpidiopsis blight and red-rot disease caused by oomycete pathogens and green-spot disease caused by PyroV1 virus. We hypothesized that a basic genetic profile of molecular defenses will be revealed by comparing and analyzing genetic response of Pyropia tenera against the above three pathogens. RNAs isolated from infected thalli were hybridized onto an oligochip containing 15,115 primers designed from P. tenera ESTs. Microarray profiles of the three diseases were compared and interpreted together with histochemical observation. Massive amounts of reactive oxygen species (ROS) were accumulated in P. tenera cells exposed to oomycete pathogens. Heat shock genes and serine proteases were the most highly upregulated genes in all infection experiments. Genes involved in RNA metabolism, ribosomal proteins and antioxidant metabolism were also highly upregulated. Genetic profiles of P. tenera in response to pathogens were most similar between the two biotrophic pathogens, Olpidiopsis pyropiae and PyroV1 virus. A group of plant R-gene homologues were specifically regulated against each pathogen. Our results suggested that disease resistance of P. tenera consist of a general and constitutive defense and a genetic toolkit against specific pathogen. Overall design: In this study presented here, 4 samples of Pyropia tenera were analyzed. Non disease infected P. tenera thalli was used as control and three disease infected thalli were used as treatment. RNAs isolated from non-infected and infected thalli were hybridized onto an oligochip containing 15,115 primers designed from P. tenera ESTs. Microarray profiles of each samples were compared and interpreted three times.
Project description:The red seaweed Pyropia yezoensis is an ideal research model for dissecting the molecular mechanisms underlying its robust acclimation to abiotic stresses in intertidal zones. Glycine betaine (GB) was an important osmolyte in maintaining osmotic balance and stabilizing the quaternary structure of complex proteins under abiotic stresses (drought, salinity, etc.) in plants, animals, and bacteria. However, the existence and possible functions of GB in Pyropia remain elusive. In this study, we observed the rapid accumulation of GB in desiccated Pyropia blades, identifying its essential roles in protecting Pyropia cells against severe osmotic stress. Based on the available genomic and transcriptomic information of Pyropia, we computationally identified genes encoding the three key enzymes in the GB biosynthesis pathway: phosphoethanolamine N-methyltransferase (PEAMT), choline dehydrogenase (CDH), and betaine aldehyde dehydrogenase (BADH). Pyropia had an extraordinarily expanded gene copy number of CDH (up to seven) compared to other red algae. Phylogeny analysis revealed that in addition to the one conservative CDH in red algae, the other six might have originated from early gene duplication events. In dehydration stress, multiple CDH paralogs and PEAMT genes were coordinating up-regulated and shunted metabolic flux into GB biosynthesis. An elaborate molecular mechanism might be involved in the transcriptional regulation of these genes.