RESUMO
Bell pepper plants are sensitive to environmental changes and are significantly affected by abiotic factors such as UV-B radiation and cold, which reduce their yield and production. Various approaches, including omics data integration, have been employed to understand the mechanisms by which this crop copes with abiotic stress. This study aimed to find metabolic changes in bell pepper stems caused by UV-B radiation and cold by integrating omic data. Proteome and metabolome profiles were generated using liquid chromatography coupled with mass spectrometry, and data integration was performed in the plant metabolic pathway database. The combined stress of UV-B and cold induced the accumulation of proteins related to photosynthesis, mitochondrial electron transport, and a response to a stimulus. Further, the production of flavonoids and their glycosides, as well as affecting carbon metabolism, tetrapyrrole, and scopolamine pathways, were identified. We have made the first metabolic regulatory network map showing how bell pepper stems respond to cold and UV-B stress. We did this by looking at changes in proteins and metabolites that help with respiration, photosynthesis, and the buildup of photoprotective and antioxidant compounds.
RESUMO
BACKGROUND: Bell pepper (Capsicum annuum L.) is one of the most economically and nutritionally important vegetables worldwide. However, its production can be affected by various abiotic stresses, such as low temperature. This causes various biochemical, morphological and molecular changes affecting membrane lipid composition, photosynthetic pigments, accumulation of free sugars and proline, secondary metabolism, as well as a change in gene expression. However, the mechanism of molecular response to this type of stress has not yet been elucidated. METHODS AND RESULTS: To further investigate the response mechanism to this abiotic stress, we performed an RNA-Seq transcriptomic analysis to obtain the transcriptomic profile of Capsicum annuum exposed to low temperature stress, where libraries were constructed from reads of control and low temperature stress samples, varying on average per treatment from 22,952,190.5-27,305,327 paired reads ranging in size from 30 to 150 bp. The number of differentially expressed genes (DEGs) for each treatment was 388, 417 and 664 at T-17 h, T-22 h and T-41 h, respectively, identifying 58 up-regulated genes and 169 down-regulated genes shared among the three exposure times. Likewise, 23 DEGs encoding TFs were identified at T-17 h, 30 DEGs at T-22 h and 47 DEGs at T-42 h, respectively. GO analysis revealed that DEGs were involved in catalytic activity, response to temperature stimulus, oxidoreductase activity, stress response, phosphate ion transport and response to abscisic acid. KEGG pathway analysis identified that DEGs were related to flavonoid biosynthesis, alkaloid biosynthesis and plant circadian rhythm pathways in the case of up-regulated genes, while in the case of down-regulated genes, they pertained to MAPK signaling and plant hormone signal transduction pathways, present at all the three time points of low temperature exposure. Validation of the transcriptomic method was performed by evaluation of five DEGs by quantitative polymerase chain reaction (q-PCR). CONCLUSIONS: The data obtained in the present study provide new insights into the transcriptome profiles of Capsicum annuum stem in response to low temperature stress. The data generated may be useful for the identification of key candidate genes and molecular mechanisms involved in response to this type of stress.
