Differential Gene Expression Analysis of Neopyropia yezoensis (Bangiales, Rhodophyta) Mutant with High-growth and Development of SSR Marker Using RNA-seq

Neopyropia yezoensis is a type of red macroalgae that is becoming economically important owing to increasing demand. A high-growth-rate mutant, NyEMS, was recently developed using ethyl methanesulfonate to meet this demand. However, the high-growth-rate mechanisms of NyEMS have not yet been identified because of the poor understanding of N. yezoensis biomolecules. In this study, NyEMS was subjected to comparative transcriptome analysis using RNA-seq. As a result, total of 7,933 differentially expressed unigenes were identified. From the transcriptome analysis, it was demonstrated that increased proteasome expression and repressed 1- aminocyclopropane-l-carboxylate (ACC) production could be responsible for the enhanced growth rate of the mutant. Additionally, genes involved in vitamin B6 biosynthesis were up-regulated, while those related to phycobilisomes were downregulated in the mutant, which could be responsible for its characteristic features. Moreover, 1,281 SNPs and 12,963 cSSRs were identified from assembled data. To determine possible biomarkers, primer pairs were designed from the identified cDNAderived simple sequence repeats. This study expands our understanding of the genetic mechanisms of N. yezoensis for future research and will be helpful in the development of N. yezoensis biomarkers.