Molecular Mechanism Research Of Sporobolomyces Pararoseus Carotenoids In Response To Salt Stress

Salt stress is one of the most important natural abiotic stresses,limiting the normal growth and development of biological cells.Salt-tolerant biological research is of great value in revealing the salt-tolerant regulation mechanism to enhance the molecular breeding of economic crops.Currently,most of the salt-tolerant biological studies are focused on botany.Due to long-term survival in a high-salt marine ecosystem,marine red yeasts must have evolved some of species-specific regulation mechanisms that responds and resists salt stress.However,little research has been performed on the salt tolerance mechanism of marine red yeasts.Therefore,this paper uses marine red yeast Sporobolomyces pararoseus as a material to analyze its growth status,carotenoid content,reactive oxygen species,transcriptomics,metabolomics and genomics under salt stress.The main research results obtained in this paper are as follows:1.Under the condition of 0.75 M Na Cl stress,the yield of torulene and torularhodin,and the intracellular reactive oxygen species level were significantly increased.After the inhibition of carotenoid synthesis by diphenylamine,the salt tolerance of S.pararoseus was significantly decreased,and the intracellular reactive oxygen species level was significantly improved.These results showed that S.pararoseus increases the production of torulene and torularhodin to remove excess reactive oxygen species as its main salt-tolerant method in response to salt stress.Torulene and torularhodin should be listed as two novel high-efficiency biological salt-tolerant molecules.2.Transcriptome analysis showed that 3849 genes were significantly differentially expressed under 0.75 M Na Cl stress,of which 2019 were up-regulated and 1830 were down-regulated.The geranylgeranyl diphosphate synthase gene crt E and phytoene dehydrogenase gene crt I,phytoene synthase/lycopene cyclase gene crt YB were significantly up-regulated,which should be the main reason for the overproduction of torulene and torularhodin.Other antioxidant enzymes and common salt-tolerant pathway-encoding genes have also been significantly differentially expressed,which should be the secondary salt-tolerant method of S.pararoseus.3.Metabolome analysis showed that total 4,862 metabolites were identified in the S.pararoseus cells under 0.75 M Na Cl stress,of which 104 were up-regulated and 272 were down-regulated.These metabolites were significantly enriched in amino acid metabolism,carbohydrate metabolism and lipid metabolism pathways.The association analysis of transcriptome and metabolome reealed that the common pathways were mostly enriched in amino acid metabolism,carbohydrate metabolism and lipid metabolism,of which 28 genes and 8 metabolites played a central regulation role in the response of salt stress.4.Genome-wide analysis showed that the S.pararoseus genome was sequenced and assembled into 20.9 Mb containing 54 scaffolds and 5963 predicted genes with a N50 length of 2,038,020 bp and GC content of 47.59%.Comparative genomic analysis revealed that the species-specific genes assigned to membrane formation,energy metabolism,and cell motility,which are probably responsible for the ballistospores-shooting in S.pararoseus.In conclusion,the molecular mechanism of S.pararoseus in response to salt stress will provide genetic resources and theoretical references of marine red yeast for salt tolerance biology research.