| Sugar beet is the second largest sugar crop in China,and improving its stress tolerance is of great production significance.Selenium has a variety of biological functions,and supplementing exogenous selenium can improve the stress tolerance of plants.In this study,a sugar beet variety HD802 was used as the test material,and when the sugar beet grew to 6 and 8 true leaves,different concentrations of nanoselenium and sodium selenite were sprayed for 24 h and then sampled.The enzyme activities and MDA contents of SOD,POD and CAT in the antioxidant system were determined,and samples with significant antioxidant resistance between different treatments were selected for transcriptome sequencing.Analysis of differential genes and metabolic pathways expressed by sugar beets in response to exogenous selenium enrichment.In order to explore the molecular mechanism of the effect of exogenous selenium on the antioxidant properties of sugar beets at the seedling stage of sugar beet,so as to improve the production value of stress resistance at the seedling stage of sugar beet.The main findings of the paper are as follows:The analysis of antioxidant defense indexes of sugar beet leaves was significantly better than that of sugar beet leaves when sprayed with different concentrations of nanoselenium at different seedling ages.The MDA content at 50 mg/L and 150 mg/L concentrations at the 8-leaf stage was significantly higher than that at the 6-leaf stage.At the same time,the activities of SOD,POD and CAT enzymes were significantly higher than those at the 6-leaf stage.The oxidation resistance of leaves is nano-selenium50 mg/L;The inhibitory effect is 150 mg/L.Compared with the control group,50 mg/L treatment increased by 2.88% at the 6-leaf stage.It was reduced by 26.62% at the 8-leaf stage.CAT enzyme activity changed significantly in both leaf stages.There were no significant changes in SOD and POD enzymes in the two leaf stages,and the SOD activities in the two leaf stages were similar.The MDA content of 150 mg/L treatment increased by 18.10% and 29.86% at the 6-leaf and 8-leaf stages,respectively.The activities of POD and CAT enzymes changed significantly at the 8-leaf stage,but there was no significant difference in the 6-leaf stage.There was no significant change in SOD enzyme activity in the two leaf stages,and the activity was similar.Different concentrations of sodium selenite were sprayed at different seedling ages,and the analysis of antioxidant defense indexes of sugar beet leaves showed that the8-leaf stage was significantly better than that of the 6-leaf stage.The MDA content at100 mg/L in the 8-leaf stage was significantly higher than that at the 6-leaf stage.The activities of SOD,POD and CAT enzymes at the 8-leaf stage were significantly higher than those at the 6-leaf stage.The MDA content of 100 mg/L treatment increased by5.76% and 25.16% at the 6-leaf and 8-leaf stages,respectively.The activities of POD and CAT enzymes were significantly different from those in the control group at the8-leaf stage,and significantly higher than those at the 6-leaf stage.When sugar beet grew to the 8-leaf stage,the differential genes of the nanoselenium 50 mg/L treatment group were mainly enriched in phosphorylation transfer signal transduction system,photosynthesis,cell response to stimulus,signal transduction and membrane.The differential genes in the beet leaf response to nanoselenium 150 mg/L treatment group were mainly enriched in phosphoric acid relay transfer signal transduction system,photosynthesis,signal transduction,cell communication,glutathione metabolism,etc.The metabolic pathways of sugar beet leaves in response to nanoselenium 50 mg/L and 150 mg/L treatment were mainly enriched in photosynthesis-antenna protein,plant-pathogen interaction,glutathione metabolism,etc.The differential genes in response to sodium selenite 100 mg/L treatment in sugar beet leaves were mainly enriched on the cell membrane.The metabolic pathway is mainly enriched in the synthesis of secondary metabolites,plant-pathogen interaction,and glutathione metabolism.With the increase of seedling age,exogenous selenium spraying had a more obvious effect on the antioxidant defense system of sugar beet,and transcriptional analysis showed that the difference genes in the photosynthesis-antenna protein pathway under the treatment of beet nanoselenium showed significant differences,and sodium selenite had significant differential gene enrichment in the secondary metabolic pathway.In summary,under the treatment of exogenous selenium,the enzyme activity of the antioxidant system affected significantly higher than that at the 8-leaf stage.In the8-leaf stage,selenium-responsive genes are mainly enriched in phosphorylation transfer signal transduction systems,photosynthesis,cellular response to stimuli,signal transduction,and membranes.Among the metabolic pathways,the pathways that have a significant impact on the antioxidant system are photosynthesis—antenna protein,glutathione metabolism,and plant hormone signaling.Among them,nanoselenium 50mg/L treatment significantly promoted photosynthesis,and glutathione S-transferase was significantly downregulated in the antioxidant system. |
PDF Full Text Request