| Astragalus mongholicus Bunge is a leguminous perennial herb and one of the source plants of Chinese medicine Astragalus.Astragalus is a famous nourishing Chinese medicinal material and a traditional bulk export commodity.Due to the over-excavation of wild resources,the current commercial Astragalus is mainly derived from artificially cultivated Astragalus mongolica.Seeds are used as the propagation material and genetic carrier of Astragalus mongolica,and exploring its senescence changes and suitable storage conditions is of great significance for the standardized cultivation of Astragalus membranaceus and the preservation of germplasm resources.In this study,Astragalus mongolica seeds were used as test materials to explore the relationship between seed senescence and its physiological and biochemical changes,and to screen suitable storage conditions and exogenous agents to delay its senescence.The main findings are as follows:1.The seeds of Astragalus mongolica with different water content(3.7%,6.6%,9.8%)were stored indoors and in the genebank(short-term,medium-term,and long-term),and the germination rate of the seeds continued to decrease with time.Store under these 4 conditions after 12 months,the germination rates of seeds with a water content of 9.8% were 27.7%,39.3%,42.3%,and 47.3%;the germination rates of seeds with a water content of 6.6% were 32.3%,42.3%,44.0%,and 53.3%,respectively;The germination rates of seeds with a water content of 3.7% were 35%,44.7%,49.7%,and 62.0%respectively.During storage,the active oxygen content of seeds increased,SOD activity increased,APX activity continued to decrease,toxic substances MDA gradually accumulated,soluble protein and The content of soluble sugar decreases;seed water content and storage temperature synergistically affect seed vigor.Low water content and low temperature conditions are more conducive to maintaining seed vigor and greatly reducing the decline in germination rate during seed storage.Therefore,the suitable storage conditions for Astragalus mongolica seeds are: water content is 3.7%,temperature is-18℃.2.Controlled deterioration treatment(CDT)was performed on seeds with different water contents(3.7%,6.6%,9.8%),and Astragalus mongolica seeds with different vigor levels were quickly obtained.The results showed that the germination rate of seeds with different water contents was as good as The germination index showed a downward trend,and was negatively correlated with water content.With the prolonged deterioration time,the active oxygen content of seeds with different moisture content all showed an upward trend;antioxidant enzyme activity and SOD activity increased,APX,DHAR,MDHAR and GR activities all showed an overall downward trend;MDA content showed an upward trend;The content of soluble sugar and soluble protein showed a downward trend.Low-water content seeds have higher antioxidant capacity and resistance to external stimuli than high-water content Astragalus mongolica seeds.3.Using non-targeted metabonomics technology to detect the different metabolites of Astragalus mongolica seeds with different vigor levels,and screen out five metabolites(5,10-methylenetetrahydrofolate,two Hydrofolate,stachyose,raffinose,sphingolipid),involving three metabolic pathways(folic acid-mediated one-carbon metabolism,sphingolipid metabolism,galactose metabolism),these metabolites and metabolic pathways may be related to seed resistance.4.The seeds were pretreated with exogenous agents and then aged.The results showed that the active oxygen content of Astragalus mongolica seeds increased after aging,the mitochondrial membrane potential decreased,and the seed germination rate and germination index decreased.Pretreatment of Astragalus mongolica seeds with appropriate concentrations of NAC and CsA can reduce the accumulation of active oxygen during seed aging,inhibit the decline of mitochondrial membrane potential,increase the anti-aging ability of seeds,and delay the decline of seed vigor. |
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