Exogenous Spermidine Promotes Germination of Aged Sorghum Seeds by Mediating Sugar Metabolism

Abstract

Starch, a substance stored in seeds, is the main source of energy for germination in sorghum seeds. However, as the seeds age, the catabolism of seed starch is affected, thereby seriously damaging germination ability. In this study, we aimed to understand how exogenous spermidine promoted germination in aged sorghum seed. Our phenotypic analysis indicated that exogenous spermidine not only significantly improved the germination rate, germination potential, germination index, and vigor index of aged seeds, but also increased the root and shoot length after germination. Further, physiological analysis showed that exogenous spermidine increased the content of soluble sugar by upregulating the activity of amylase and sucrose invertase. Exogenous spermidine also improved the activities of key enzymes in glycolysis, the tricarboxylic acid cycle, and the pentose phosphate pathway of aged sorghum seeds. Interestingly, exogenous spermidine protected the mitochondrial structure of aged seeds, which was consistent with the increase in the respiration rate and ATP content during seed germination. Moreover, qRT-PCR analysis revealed that exogenous spermidine induced the expression of key genes related to starch and sugar metabolism in aged sorghum seeds. In conclusion, our study demonstrated that exogenous spermidine promoted aged sorghum seed germination by regulating starch and sugar metabolism.

Aging-Induced Reduction in Safflower Seed Germination via Impaired Energy Metabolism and Genetic Integrity Is Partially Restored by Sucrose and DA-6 Treatment

“…Moreover, research has shown that CSN improves germination and seedling establishment in aged sunflower seeds by increasing FA conversion into sucrose [ 12 ]. Another study found that exogenous spermidine promotes sorghum seed germination by promoting starch and sugar utilization [ 10 ]. As safflower is an essential economic crop that relies on high-quality seeds for efficient and effective plant production, the ability to enhance germination in aged seeds potentially has huge implications for agriculture.…”

“…Germination was recorded after seven days with germination defined as radicle emergence by >2mm. The parameters of germination that were determined were [ 10 ]: Germination rate = the number of normally germinated seeds on the 7th day/the total number of tested seeds × 100% Germination potential = the number of normally germinated seeds on the 2nd day/the total number of tested seeds × 100% Germination index = ∑(Gt/Dt) where Gt is the number of germinations on the 7 days; Dt is the number of germination days.…”

“…Germination was recorded after seven days with germination defined as radicle emergence by >2mm. The parameters of germination that were determined were [10]:…”

“…DHAP is involved in the glycolysis pathway and is utilized during seed germination. Soluble sugars are eventually catabolized into ATP which is the most direct form of energy for seed germination and growth [ 10 ]. However, in aging soybean and sunflower seeds, fatty acids’ conversion into sucrose can be hampered at the early stage of germination and is recognized as the principal cause for decreased soybean seed vigor after storage [ 11 , 12 ].…”

Enhanced meristem development, tolerance to oxidative stress and hyposensitivity to nitric oxide in the hypermorphic vq10‐H mutant in AtVQ10 gene

“…Future work will be needed to determine whether the changes in the endogenous levels of starch may be linked to altered VQ10 gene expression and to phenotypes such as altered root growth or sensitivity to nitroxidative stress described in this article. However, starch that is stored in seeds, is the main source of energy for germination and it was documented that the starch content affect seed germination through alterations in the starch‐sugars balance due to altered starch metabolism (Zhang et al, 2022). We checked whether the energy status of plants with enhanced VQ10 expression was significantly different from wild‐type plants either under non‐stressed conditions or upon nitroxidative stress caused by application of exogenous NO.…”