Analysis of Transcriptome and Differentially Expressed Genes Involved in Antioxidant Enzymes and Flavonoids Biosynthesis against UV-B Stress in the Desert Plant, Reaumuria Soongorica

Reaumuria soongorica (Pall.) Maxim., a typical species of desert plant, presents excellent tolerability to adverse environment. Until yet, little is known about the molecular mechanisms of stress tolerance in R. soongorica. Herein, we used the RNA-seq to study the transcriptome of R. soongorica leaves. The differentially expressed genes (DEGs) involved in antioxidant enzymes and flavonoids under UV-B treatment were examined. De novo assembly produced 66,117 unigenes with an average length of 722 bp. Based on sequence similarity with known proteins, 38,762 (58.62%) genes had known homologs in protein databases. Out of these annotated unigenes, 29,460 and 13,582 unigenes had at least one gene ontology classification or were assigned to clusters of orthologous group, respectively. Searching against the Kyoto Encyclopedia of Genes and Genomes Pathway database (KEGG) showed that 21,202 (32.06%) unigenes were classified to 128 KEGG pathways. In addition, 7,711 simple sequence repeats (SSRs) and 216,851 single nucleotide polymorphisms (SNPs) were identified as potential molecular markers. The DEGs analysis between control and UV-B treated plants showed that the DEGs involved in antioxidant enzymes system were down-regulated. However, the DEGs involved in flavonoid pathway were up-regulated under UV-B stress. The transcriptome of R. soongorica prepared a foundation for further studies on gene interaction and regulation. Thousands of SSRs and SNPs markers identified can facilitate studies on genetic variation in R. soongorica. Additionally, the analysis of DEGs implied that R. soongorica resists to UV-B stress by up-regulation of flavonoids biosynthesis.