Key Laboratory of Quality and Safety Control for Subtropical Fruit and Vegetable, Ministry of Agriculture and Rural Affairs, Collaborative Innovation Center for Efficient and Green Production of Agriculture in Mountainous Areas of Zhejiang Province, College of Horticulture Science, Zhejiang A&F University, Hangzhou 311300, China.
Department of Biotechnology, University of Houston Clear Lake, Houston, TX 77058-1098, USA.
Int J Mol Sci. 2023 Mar 29;24(7):6429. 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.
白菜（L. ssp.）对高温敏感，高温会导致其处于半休眠状态。研究证明，在热胁迫前对白菜叶片进行 GB 喷雾可以增强其耐热性。为了了解 GB 引发的耐热性或对热应激的适应的分子机制，我们通过 RNA-Seq 分析研究了 GB 引发和非引发的热敏白菜‘北京 3 号’品种的转录组。共鉴定出 582 个差异表达基因（DEGs），这些基因在热胁迫下的 GB 引发植物中与非引发植物相比表达上调，这些基因被分配到 350 个基因本体（GO）途径和 69 个京都基因与基因组百科全书（KEGG）途径。KEGG 富集途径分析表明，上调最丰富的途径是内质网蛋白加工（14 个基因），其次是植物激素信号转导（12 个基因）、核糖体（8 个基因）、MAPK 信号通路（8 个基因）、同源重组（7 个基因）、核苷酸切除修复代谢（5 个基因）、谷胱甘肽代谢（4 个基因）和抗坏血酸和醛酸盐代谢（4 个基因）。下调最丰富的途径是植物-病原体相互作用（14 个基因），其次是苯丙烷生物合成（7 个基因）；精氨酸和脯氨酸代谢（6 个基因）；角质、栓皮和蜡生物合成（4 个基因）和色氨酸代谢（4 个基因）。在热胁迫下，钙感应/转导蛋白以及与脱落酸（ABA）、水杨酸（SA）、生长素和细胞分裂素激素相关的转录因子在 GB 引发的植物中要么上调，要么下调。特别是，抗氧化防御、热休克反应和 DNA 损伤修复系统的基因表达因 GB 引发而显著增加。另一方面，在 GB 引发的幼苗中，许多参与植物先天免疫和次生代谢物生物合成的钙传感器和细胞表面受体的基因表达下调，而没有病原体诱导剂。总的来说，GB 引发激活了 ABA 和 SA 信号通路，但抑制了生长素和细胞分裂素信号通路，同时抑制了热胁迫下幼苗的先天免疫。本研究初步了解了 GB 引发植物的耐热性机制，对于通过遗传修饰利用鉴定出的 DEGs 培育耐热白菜品种具有重要意义。
