Transcriptome Sequencing and Analysis of Leymus Chinensis under Sakine-alkaline Treatment

Leymus chinensis (Trin.) Tzvel. is a high saline-alkaline tolerant forage grass genus of the tribe Gramineae family, which also plays an important role in protection of natural environment. To date, little is known about the saline-alkaline tolerance of L. chinensis on the molecular level. To better understand the molecular mechanism of saline-alkaline tolerance in L. chinensis, We used Roche-454massive parallel pyrosequencing technology to sequence two different cDNA libraries that were built from the two samples of control and under saline-alkaline treatment (Optimal stress concentration-Hoagland solution with100mM NaCl and200mM NaHCO3), the main results as follows:1. Afrer measuring the proline (PRO) contents, superoxide dismutase (SOD) activities, and malondialdehyde (MDA) contents of all the collected samples, we obtained that the optimal saline-alkaline stress concentration was NaCl-100mmol/L and NaHCO3-200mmol/L for the second day, which was finally as the treatment group for the following experiments, sequencing and qRT-PCR.2. After sequencing, the reads were assembled into104,105unigenes with MIRA sequence assemable software, among which,16,089unigenes were in control group,30,440unigenes in treatment group and57,576unigenes in both groups. With the threshold of "log2Ratio≥10", there were50,514up-regulated unegenes and26,222down-regulated unigenes predicted to be the differentially expressed genes.3. After gene annotation and classification, there were10,446ungenes annotated on GO (gene ontology),5,2176unigenes annotated on KEGG (Kyoto Encyclopedia of Genes and Genomes), of which, signal transduction, energy production and conversion, and inorganic ion transport.4. After pathway enrichment analysis, calcium signaling pathway, oxidative phosphorylation pathway and NHX antiporter pathway were found up-regulated under stress. Of which,287unigenes were in calcium signaling pathway,268unigenes were in oxidative phosphorylation pathway and302unigenes were in NHX antiporter pathway.5. Furthermore, for real-time PCR validation, and12of these unigenes were successfully confirmed with the results of454pyrosequencing, the gene data base can used for the further study.