Study on the enhancement of salt tolerance of Gracilariopsis lemaneiformis through addition of exogenous substances based on transcriptome analysis

Abstract

Gracilariopsis lemaneiformis is an economic red macroalga whose cultivation is affected by salinity. To investigate the molecular mechanism of G. lemaneiformis response to salt stress, transcriptome sequencing was used to analyze the differentially expressed genes of wild G. lemaneiformis cultured at low (10‰), normal (30‰) and high (40‰) salinities. After the algae were treated for seven days at 10‰ and 40‰ salinity, a total of 1016 and 1231 differently expressed genes were discovered, respectively. Through GO and KEGG pathway analysis, the transcription of genes involved in lysine biosynthesis, ascorbic acid biosynthesis and TCA cycling were up-regulated significantly under low salt stress. The transcription of genes related to glycogen degradation and ABC transporters pathway was significantly up-regulated under high salt stress. Meanwhile, the transcription of genes related to lignin and trehalose biosynthesis, which can enhance plant stress resistance, was up-regulated significantly under both low and high salt stress. Based on the transcriptome results, lysine, ascorbic acid, and trehalose were added to the culture system of G. lemaneiformis. The results showed that the addition of certain concentrations of exogenous lysine and trehalose enhanced the growth and salt stress tolerance of wild G. lemaneiformis. This study investigates the molecular mechanism of salt response of G. lemaneiformis and provides an experimental basis to improve the salt tolerance of G. lemaneiformis by adding exogenous substances.