Mathematical Modeling Reveals That Sucrose Regulates Leaf Senescence via Dynamic Sugar Signaling Pathways

文献类型： 外文期刊

第一作者： Asim, Muhammad

作者： Asim, Muhammad;Wang, Xiaolin;Sun, Yanguo;Liu, Haiwei;Khan, Rayyan;Du, Shasha;Shi, Yi;Zhang, Yan;Hussain, Quaid;Zhang, Yan

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关键词： sucrose concentration; sugar signaling dynamics; glucose; trehalose-6-phosphate; SnRK1; senescence

期刊名称：INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES （ 影响因子：6.208； 五年影响因子：6.628 ）

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年卷期： 2022 年 23 卷 12 期

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收录情况： SCI

摘要： Sucrose (Suc) accumulation is one of the key indicators of leaf senescence onset, but little is known about its regulatory role. Here, we found that application of high (120-150 mM) and low levels (60 mM) of Suc to young leaf (YL) and fully expanded leaf (FEL) discs, respectively, decreased chlorophyll content and maximum photosynthetic efficiency. Electrolyte leakage and malondialdehyde levels increased at high Suc concentrations (90-120 mM in YL and 60 and 150 mM in FEL discs). In FEL discs, the senescence-associated gene NtSAG12 showed a gradual increase in expression with increased Suc application; in contrast, in YL discs, NtSAG12 was upregulated with low Suc treatment (60 mM) but downregulated at higher levels of Suc. In YL discs, trehalose-6-phosphate (T6P) accumulated at a low half-maximal effective concentration (EC50) of Suc (1.765 mM). However, T6P levels declined as trehalose 6 phosphate synthase (TPS) content decreased, resulting in the maximum velocity of sucrose non-fermenting-1-related protein kinase (SnRK) and hexokinase (HXK) occurring at higher level of Suc. We therefore speculated that senescence was induced by hexose accumulation. In FEL discs, the EC50 of T6P occurred at a low concentration of Suc (0.9488 mM); T6P levels progressively increased with higher TPS content, which inhibited SnRK activity with a dissociation constant (K-d) of 0.001475 U/g. This confirmed that the T6P-SnRK complex induced senescence in detached FEL discs.

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