Starch and Sucrose Metabolism and Plant Hormone Signaling Pathways Play Crucial Roles in Aquilegia Salt Stress Adaption

Abstract

Salt stress is one of the main abiotic stresses that strongly affects plant growth. Clarifying the molecular regulatory mechanism in ornamental plants under salt stress is of great significance for the ecological development of saline soil areas. Aquilegia vulgaris is a perennial with a high ornamental and commercial value. To narrow down the key responsive pathways and regulatory genes, we analyzed the transcriptome of A. vulgaris under a 200 mM NaCl treatment. A total of 5600 differentially expressed genes were identified. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis pointed out that starch and sucrose metabolism and plant hormone signal transduction were significantly improved. The above pathways played crucial roles when A. vulgaris was coping with salt stress, and their protein-protein interactions (PPIs) were predicted. This research provides new insights into the molecular regulatory mechanism, which could be the theoretical basis for screening candidate genes in Aquilegia.

Keywords: Aquilegia vulgaris; RNA sequencing; plant hormone signal transduction; salt stress; starch and sucrose metabolism.

Figure 1

The lengths of the genes.

Figure 2

Correlation analysis and principal component analysis (PCA): (A) sample correlation analysis; (B) sample distributions in PCA 1 and PCA 2.

Figure 3

Differentially expressed genes (DEGs): (A) numbers of DEGs in each time node; (B) Venn diagrams for 12 h vs. 0 h and 24 h vs. 0 h; (C) Venn diagrams for 12 h vs. 0 h and 48 h vs. 0 h; (D) Venn diagrams for 24 h vs. 0 h and 48 h vs. 0 h; (E) Venn diagrams for 12 h vs. 0 h and 24 h vs. 0 h and 48 h vs. 0 h; (F) volcano plots for 12 h vs. 0 h; (G) volcano plots for 24 h vs. 0 h; (H) volcano plots for 48 h vs. 0 h.

Figure 3

Differentially expressed genes (DEGs): (A) numbers of DEGs in each time node; (B) Venn diagrams for 12 h vs. 0 h and 24 h vs. 0 h; (C) Venn diagrams for 12 h vs. 0 h and 48 h vs. 0 h; (D) Venn diagrams for 24 h vs. 0 h and 48 h vs. 0 h; (E) Venn diagrams for 12 h vs. 0 h and 24 h vs. 0 h and 48 h vs. 0 h; (F) volcano plots for 12 h vs. 0 h; (G) volcano plots for 24 h vs. 0 h; (H) volcano plots for 48 h vs. 0 h.

Figure 4

Gene Ontology (GO) enrichment analysis in the following groups: (A) 12 h vs. 0 h; (B) 24 h vs. 0 h; (C) 48 h vs. 0 h.

Figure 4

Gene Ontology (GO) enrichment analysis in the following groups: (A) 12 h vs. 0 h; (B) 24 h vs. 0 h; (C) 48 h vs. 0 h.

Figure 5

Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis in the following groups: (A) 12 h vs. 0 h; (B) 24 h vs. 0 h; (C) 48 h vs. 0 h.

Figure 6

Heat map of annotated genes in starch and sucrose metabolism pathway. Solid lines and arrows represent biological processes and directions, while areas separated by dotted lines represent different types of biological processes. (A) Trehalose synthesis process; (B) starch synthesis process; (C) sucrose synthesis and hydrolysis process; (D) starch hydrolysis process; (E) cellulose hydrolysis process.

Figure 7

Heat map of annotated genes in plant hormone signal transduction pathway. Solid lines and arrows indicate the signal transduction process and direction. (A) Indole-3-acetic acid (IAA) signaling pathway; (B) cytokinin (CK) signaling pathway; (C) gibberellin (GA) signaling pathway; (D) abscisic acid (ABA) signaling pathway; (E) brassinolide (BR) signaling pathway; (F) jasmonic acid (JA) signaling pathway.

Figure 7

Heat map of annotated genes in plant hormone signal transduction pathway. Solid lines and arrows indicate the signal transduction process and direction. (A) Indole-3-acetic acid (IAA) signaling pathway; (B) cytokinin (CK) signaling pathway; (C) gibberellin (GA) signaling pathway; (D) abscisic acid (ABA) signaling pathway; (E) brassinolide (BR) signaling pathway; (F) jasmonic acid (JA) signaling pathway.

Figure 8

Protein–protein interaction (PPI) network among the starch and sucrose metabolism pathway and the plant hormone signal transduction pathway. The blue and red nodes represent the sucrose metabolism pathway and the plant hormone signal transduction pathway, respectively. The diameters of the nodes represent the interaction frequency.

Figure 9

Log 2-fold changes of 16 genes in quantitative real-time PCR (qRT-PCR) and RNA-seq.