Transcriptome Sequencing Mines Genes Related to the Development of Apical Bud Differentiation in Leymus chinensis Rhizomes

This study uses the below-ground bud bank of Leymus chinensis (Trin.) Tzvel growing in the saline meadows of Songnen, Northeast China, was used as the material, and four samples of rhizome apical shoots and upward-growing rhizome apical shoots different growth nodes were selected, and their RNA was extracted to establish the libraries. The libraries were analyzed using high-throughput transcriptome sequencing as a way to understand the differences in gene expression between horizontal and upward rhizome apex buds, and to mine for genes expressed in the upward-bending apex buds. A total of 95,759 non-redundant unigene with lengths greater than 200 bp were obtained after novo assembly of the L. chinensis transcripts; 70,656 unigene with annotation information were finally obtained in this study by controlling the BLAST parameter E-value and the HMMER parameter E-value, as well as by comparison with the NR, Swiss-Prot, KEGG, COG, KOG, and Pfam databases. SSR analysis yielded a total of 7,952 SSR markers and SNP analysis. Comparison of transcriptome gene differences showed that T03 and T04 up-regulated 1266 unigenes and down-regulated 663 unigene of expressed genes relative to T01 and T02. In order to more visually display unigene expression and gene expression differences, box-and-line plots and heat maps were drawn. The results indicate that both up- and down-regulated genes at the growth node have the potential to influence the development of straight apical buds in underground rhizomes and induce curved apical buds in rhizomes. Therefore, the detected differentially expressed genes were functionally annotated, while the GO database was used for functional enrichment of differentially expressed genes. The results of this study can provide a theoretical basis for the molecular genetic breeding of L. chinensis and in artificially regulating the transition time from straight to curved buds of lay a theoretical foundation for the planting and popularization of L. chinensis in saline areas.