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The genus Pyropia contains several important cultivated species. Genetic research in nori species has mainly focused on the cell nucleus, with few studies on organelles (chloroplast and mitochondria). Due to the high copy numbers of organelles in cells, which influence the development and traits of algae, it is necessary to study their genetic mechanism. In this study, the marine red alga Pyropia yezoensis, an important economic macroalga, was selected as the study object. To investigate organelle (chloroplast and mitochondria) inheritance in P. yezoensis, the wild type RZ (maternal strain) was crossed with the red mutant HT (paternal strain) and 30 color-sectors from 11 F1 gametophytic blades were examined. The complete chloroplast and mitochondrial genomes of the red mutant (HT) were assembled for the first time. One reliable and stable single nucleotide polymorphism (SNP) loci filtrated by bioinformatics analysis was used as a molecular marker for chloroplast and mitochondrial DNA, respectively, in subsequent experiments. PCR amplification and sequence analysis showed that the haplotypes of color-sectors detected were consistent with those of the maternal parent, confirming that both chloroplast and mitochondrial genomes were inherited maternally in P. yezoensis. The inheritance pattern of organelles in P. yezoensis can be used to guide the hybridization and breeding of nori. Additionally, the organelle SNP markers developed in this study can be applied in subsequent genetic research. [ABSTRACT FROM AUTHOR]

Pyropia yezoensis is an important macroalga because of its extensive global distribution and economic importance. Color is an important trait in the thalli of P. yezoensis, it is also an effective marker to identify the hybridization in genetic breeding. In this study, a high-density genetic linkage map was constructed based on high-throughput single nucleotide polymorphism (SNP) markers, and used for analyzing the quantitative trait loci (QTLs) of red color trait in the thalli of P. yezoensis. The conchospore undergoes meiosis to develop into an ordered tetrad, and each cell has a haploid phenotype and can grow into a single individual. Based on this theory, F1 haploid population was used as the mapping population. The map included 531 SNP markers, 394.57 cM long on average distance of 0.74 cM. Collinear analysis of the genetic linkage map and the physical map indicated that the coverage between the two maps was 79.42%. Furthermore, QTL mapping identified six QTLs for the chromosomal regions associated with the red color trait of the thalli. The value of phenotypic variance explained (PVE) by an individual QTL ranged from 4.71%–63.11%. And QTL qRed-1-1, with a PVE of 63.11%, was considered the major QTL. Thus, these data may provide a platform for gene and QTL fine mapping, and marker-assisted breeding in P. yezoensis in the future. [ABSTRACT FROM AUTHOR]