Qualidade de sementes de Ricinus communis L. submetidas ao envelhecimento: perfil metabolômico, transcriptômico, enzimático e fisiológico

Abstract

To assess seed vigor, it is possible to perform accelerated aging (AA), which consists of submitting the seeds to high temperature and humidity. In addition, this test makes it possible to evaluate the behavior of seeds at a physiological, biochemical and molecular level. The objective of this study was to evaluate the behavior of seeds of cultivars BRS 188 Paraguaçu and BRS 149 Nordestina of Ricinus communis L. before and after being submitted to AA regarding the metabolomic, transcriptomic, enzymatic and physiological profile. The following analyzes were carried out: initial characterization of seeds, AA standardization, seed moisture contente, germination test, determination of electrical conductivity and pH exudate, tetrazolium test, lipid peroxidation (malonaldehyde levels - MDA), determination of the activities of antioxidant enzymes (superoxide dismutase – SOD, catalase – CAT, ascorbate peroxidase – APX, monodehydroascorbate reductase – MDHAR, dehydroascorbate reductase – DHAR, glutathione reductase – GR, glutathione peroxidase – GPX and glutathione S-transferase – GST). The evaluation of primary and secondary metabolites by metabolomics, and the production of transcripts through the RNA-seq test for the seeds of BRS 188 Paraguaçu. In the BRS 188 Paraguaçu seeds after the AA, there was a loss of vigor, increase in electrical conductivity, alteration in the production of primary (galactinol, myo-inossitol, melibiose, glyoxylic acid, sorbitol, inositol, xylose, sucrose and ribitol) and secondary metabolites of the terpene, phenolic and alkaloid classes, and greater gene expression, especially energy metabolismo. In response to AA, the increase in MDA concentration and APX and CAT activity was only significant in the whole seed, while SOD and DHAR were enzymes that showed a significant increase in activity in the whole seed and in the embryo. The change in GST and GPX activity was significant only in embryo samples. The cultivar BRS 149 Nordestina, showed after AA a significant reduction in viability, with membrane damage and increased lipid peroxidation. The increase in SOD activity, APX and DHAR were significant in whole seeds and the embryo, while CAT activity in the whole seed. MDHAR, GR and GPX, activity increased significantly only in the embryo. When analyzing the physiological, biochemical and molecular mechanisms of seeds after AE, that MDA, SOD and DHAR, and the increase of electrolytes in the exudate are biochemical biomarkers for the evaluation of seed quality, even as, the genes important for energy metabolism are suitable biomarkers for evaluating the quality of seeds of this species.