Transcriptomic Analysis of Heat Stress Response in Brassica rapa L. ssp. pekinensis with Improved Thermotolerance through Exogenous Glycine Betaine

• Published in: International journal of molecular sciences Vol. 24; no. 7; p. 6429
• Main Authors: Quan, Jin, Li, Xinyuan, Li, Zewei, Wu, Meifang, Zhu, Biao, Hong, Seung-Beom, Shi, Jiang, Zhu, Zhujun, Xu, Liai, Zang, Yunxiang
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 29.03.2023; MDPI
• Subjects: Abiotic stress; Abscisic acid; Abscisic Acid - metabolism; Ascorbic acid; Auxins; B. rapa; Betaine - metabolism; Biosynthesis; Brassica rapa; Brassica rapa - metabolism; Calcium; Calcium - metabolism; Cell surface; Chinese cabbage; Cultivars; Cutin; Cytokinins; Cytokinins - metabolism; DNA damage; DNA repair; Dormancy; Endoplasmic reticulum; Gene expression; Gene Expression Regulation, Plant; Genes; Genetic modification; Genomes; Glycine; Glycine betaine; Heat; Heat resistance; Heat shock; Heat shock proteins; Heat stress; Heat-Shock Response - genetics; High temperature; Hormones; HSP; Indoleacetic Acids - metabolism; Metabolism; Metabolites; Molecular modelling; Nucleotides; Oxidation; Oxidative stress; Pathogens; Photosynthesis; Plant Proteins - metabolism; protein processing in endoplasmic reticulum; Proteins; Repair; Salicylic acid; Seedlings - metabolism; Signal transduction; Temperature effects; Temperature tolerance; thermotolerance; Thermotolerance - genetics; Transcription factors; Transcriptome; Tryptophan; China; heat stress; protein processing in endoplasmic reticulum; HSP; thermotolerance; B. rapa; glycine betaine
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms24076429

Chinese cabbage ( L. ssp. ) is sensitive to high temperature, which will cause the to remain in a semi-dormancy state. Foliar spray of GB prior to heat stress was proven to enhance thermotolerance. In order to understand the molecular mechanisms of GB-primed resistance or adaptation towards heat stress, we investigated the transcriptomes of GB-primed and non-primed heat-sensitive 'Beijing No. 3' variety by RNA-Seq analysis. A total of 582 differentially expressed genes (DEGs) were identified from GB-primed plants exposed to heat stress relative to non-primed plants under heat stress and were assigned to 350 gene ontology (GO) pathways and 69 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways. The analysis of the KEGG enrichment pathways revealed that the most abundantly up-regulated pathways were protein processing in endoplasmic reticulum (14 genes), followed by plant hormone signal transduction (12 genes), ribosome (8 genes), MAPK signaling pathway (8 genes), homologous recombination (7 genes), nucleotide excision repair metabolism (5 genes), glutathione metabolism (4 genes), and ascorbate and aldarate metabolism (4 genes). The most abundantly down-regulated pathways were plant-pathogen interaction (14 genes), followed by phenylpropanoid biosynthesis (7 genes); arginine and proline metabolism (6 genes); cutin, suberine, and wax biosynthesis (4 genes); and tryptophan metabolism (4 genes). Several calcium sensing/transducing proteins, as well as transcription factors associated with abscisic acid (ABA), salicylic acid (SA), auxin, and cytokinin hormones were either up- or down-regulated in GB-primed plants under heat stress. In particular, expression of the genes for antioxidant defense, heat shock response, and DNA damage repair systems were highly increased by GB priming. On the other hand, many of the genes involved in the calcium sensors and cell surface receptors involved in plant innate immunity and the biosynthesis of secondary metabolites were down-regulated in the absence of pathogen elicitors in GB-primed seedlings. Overall GB priming activated ABA and SA signaling pathways but deactivated auxin and cytokinin signaling pathways while suppressing the innate immunity in seedlings exposed to heat stress. The present study provides a preliminary understanding of the thermotolerance mechanisms in GB-primed plants and is of great importance in developing thermotolerant cultivars by using the identified DEGs through genetic modification.