Transcriptome analysis revealed expression of genes related to anthocyanin biosynthesis in eggplant (Solanum melongena L.) under high-temperature stress

Abstract

Background: Anthocyanin synthesis is affected by many factors, among which temperature is an important environmental factor. Eggplant is usually exposed to high temperatures during the cultivation season in Shanghai, China. Therefore,RNA -seq analysis was used to determine the effects of high-temperature stress on gene expression in the anthocyanin biosynthetic pathway of eggplant (Solanum melongena L.).

Results: We tested the heat-resistant cultivar 'Tewangda'. The plants were incubated at 38 °C and 45 °C, and the suitable temperature for eggplant growth was used as a control. The treatment times were 3 h and 6 h. The skin of the eggplant was taken for transcriptome sequencing, qRT-PCR assays and bioinformatic analysis. The results showed that 770 genes were differentially expressed between different treatments. Gene Ontology (GO) database and Kyoto Encyclopedia of Genes and Genomes (KEGG) database analyses identified 16 genes related to anthocyanin biosynthesis, among which CHSB was upregulated. Other genes, including BHLH62, MYB380, CHI3, CHI, CCOAOMT, AN3, ACT-2, HST, 5MA-T1, CYP75A2, ANT17, RT, PAL2, and anthocyanin 5-aromatic acyltransferase were downregulated. In addition, the Myb family transcription factor PHL11 was upregulated in the CK 3 h vs 45 °C 3 h, CK 3 h vs 38 °C 3 h, and CK 6 h vs 38 °C 6 h comparisons, and the transcription factor bHLH35 was upregulated in the CK 3 h vs 38 °C 3 h and CK 6 h vs 38 °C 6 h comparisons.

Conclusion: These results indicated that high temperature will downregulate most of the genes in the anthocyanin biosynthetic pathway of eggplant. Our data have a reference value for the heat resistance mechanism of eggplant and can provide directions for molecular breeding of heat-resistant germplasm with anthocyanin content in eggplant.

Keywords: Anthocyanin biosynthesis; Eggplant (Solanum melongena L,); Gene expression; High temperature; Transcriptome; qRT-PCR.

Fig. 1

a Eggplant fruit pictures of different treatment groups. There were six treatments (CK-3 h, CK-6 h, 38 °C -3 h, 38 °C- 6 h, 45 °C -3 h, 45 °C- 6 h). b Anthocyanin concentration in the peel of eggplant in different treatment groups. Comparison of three different temperatures (CK,38 °C,45 °C) in three times (0 h,3 h,6 h)

Fig. 2

Venn diagram of four comparison groups of differentially expressed genes

Fig. 3

Heatmap diagrams among the six treatments. The red color in the picture indicates high expression genes, while the green color indicates low expression genes

Fig. 4

GO enrichment between the CK 6 h and 45 °C 6 h groups The X coordinates in the diagram are GO entry names, and the Y coordinates are -log10 p-values.

Fig. 5

KEGG enrichment between the CK 6 h and 45 °C 6 h groups. The Enrichment Score of X-axis is the enrichment score. The bigger the bubble, the more different genes it contains. The color of the bubble changes from purple-blue-green-red. The smaller the enrichment pvalue, the greater the significance