Study on the physiological mechanism and molecular regulatory network of Blumea balsamifera in response to drought stress

Abstract

Drought restricts plant growth and agricultural production. As an important medicinal plant, Blumea balsamifera is sensitive to water, but there is still a lack of systematic research on its drought response mechanism. In this study, four-month-old B. balsamifera seedlings were used as materials, and three groups were set up: normal irrigation (CK), drought stress (DS), and rewatering recovery (RW). The results showed that drought significantly inhibited the growth and photosynthesis of B. balsamifera. With the prolongation of stress time (day 12), the limiting factor of photosynthesis changed from initial stomatal limitation to non - stomatal limitation. In terms of physiology and biochemistry, B. balsamifera increased MDA content by actively reducing SPAD value and relative water content of leaves; and activates the antioxidant enzyme system to remove ROS, synergistically accumulates lignin, soluble sugar, proline and other osmotic adjustment substances, and jointly maintains cell water balance and membrane system stability. Through transcriptome and proteome analysis, 20,874 DEGs and 2770 DEPs were screened out, which were significantly enriched in terms related to ribosome, oxidoreductase activity, biosynthesis of unsaturated fatty acids and other pathways. A total of 55 drought - related DEGs - DEPs were identified by two - omics, and 18 key regulatory genes were screened. In summary, B. balsamifera formed a comprehensive drought resistance mechanism through photosynthesis, physiology and DEGs - DEPs network. This study provides theoretical support for the breeding and resource development of B. balsamifera, and also provides reference for the study of stress resistance of other medicinal plants.

Keywords: Blumea balsamifera L; Drought resistance mechanism; Drought stress; Proteomics; Transcriptomics.

Fig. 1

Effect of drought stress on growth and morphology of B. balsamifera. The first three time points of the RW group showed the phenotype and data of drought treatment, and the subsequent four time points showed the change of phenotype data after rehydration. A Phenotypic characters. B, C, D, E, F and G Plant height, plant height growth, basal stem diameter, leaf length, leaf width and leaf thickness. Different lower case letters in the graphs indicate significant differences (P < 0.05), and same lower case letters indicate no significant differences (P > 0.05)

Fig. 2

Effect of drought stress on photosynthesis-related parameters of B. balsamifera.A Comparison of the growth status of each group at the 12th day of treatment. B, C, D, E, F, G and H Pn, Tr, Ci, Gs, CE, Ls and WUEi. Different lowercase letters in the graphs indicate significant differences (P < 0.05), and the same lowercase letters indicate no significant differences (P > 0.05)

Fig. 3

Effect of drought stress on leaf physiology and biochemistry of B. balsamifera.A SPAD comparison. B RWC comparison. C, D, E and F MDA content, SOD, POD and CAT activities. G, H, I and J LIG, SS, SP and PRO contents. Different lowercase letters in the graphs indicate significant differences (P < 0.05), and the same lowercase letters indicate no significant differences (P > 0.05)

Fig. 4

Transcriptome expression analysis. A Principal component analysis. Each dot represents a replicate in a grouped experiment, and different colors distinguish different groups. B Volcano plot of identified genes. Purple color in the graph indicates down-regulated differentially expressed genes, red dots indicate up-regulated genes, and gray dots indicate insignificant differentially expressed genes. C GO functional enrichment of DEGs. D KEGG functional enrichment of DEGs

Fig. 5

A Principal component analysis. Each dot represents a replicate in a grouped experiment, and different colors distinguish different groups. B Volcano plot of identified proteins. Purple dots in the graph indicate down-regulated differentially expressed proteins, red dots indicate up-regulated proteins, and gray dots indicate non-significant differentially expressed proteins. C GO functional enrichment of DEPs. D KEGG functional enrichment of DEPs

Fig. 6

Joint transcriptome and proteome analysis. A Statistical data on the distribution of DEGs-DEPs in the control and drought groups. B Comparative analysis of DEGs-DEPs in control and drought groups. C Correlation analysis of mRNAs with proteins. The horizontal coordinate is the range of values of the correlation coefficients and the vertical coordinate is the density distribution of the correlation coefficients. D GO enrichment analysis of DEGs-DEPs. E KEGG pathway analysis of DEGs-DEPs

Fig. 7

Co-analysis of transcriptome and proteome. A Expression of drought tolerance-associated DEGs-DEPs. B Protein-protein interaction network, the size of the diamond or circle represents the number of proteins interacting with the protein

Fig. 8

Comparative analysis of RNA-seq and RT-qPCR

Fig. 9

Network of drought mechanisms in B. balsamifera. The green upward arrow indicates that the activity or content of the substance increases with time; the red downward arrow indicates that the activity or content of the substance decreases with time; both upward and downward arrows indicate that the activity or content of the substance increases first and then decreases with time. A phenotypic response. B photosynthetic response. C physiological and biochemical response. D molecular response, possibly regulated transcription factors