Autumn senescence in aspen (Populus tremula) is precisely timed every year to relocate nutrients from leaves to storage organs before winter. Here we demonstrate how stem girdling, which leads to the accumulation of photosynthates in the crown, influences senescence. Girdling resulted in an early onset of senescence, but the chlorophyll degradation was slower and nitrogen more efficiently resorbed than during normal autumn senescence. Girdled stems accumulated or retained anthocyanins potentially providing photoprotection in senescing leaves. Girdling of one stem in a clonal stand sharing the same root stock did not affect senescence in the others, showing that the stems were autonomous in this respect. One girdled stem with unusually high chlorophyll and nitrogen contents maintained low carbon-to-nitrogen (C/N) ratio and did not show early senescence or depleted chlorophyll level unlike the other girdled stems suggesting that the responses depended on the genotype or its carbon and nitrogen status. Metabolite analyses highlighted that the tricarboxylic acid (TCA) cycle, salicylic acid pathway and redox homeostasis are involved in the regulation of girdling-induced senescence. We propose that disrupted sink-source relation and C/N status can provide cues through the TCA cycle and phytohormone signaling to override the phenological control of autumn senescence in the girdled stems. This article is protected by copyright. All rights reserved.

中文翻译：

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茎环剥与代谢信号相互作用影响白杨秋季衰老的开始

白杨（Populus tremula）的秋季衰老每年都会精确计时，以便在冬季之前将营养物质从叶子转移到储存器官。在这里，我们展示了导致树冠中光合作用积累的茎环切是如何影响衰老的。环剥导致衰老提前开始，但与正常秋季衰老相比，叶绿素降解更慢，氮的吸收更有效。带环的茎积累或保留了花青素，可能为衰老的叶子提供光保护。对共享同一根砧木的克隆林中的一根茎进行环剥不会影响其他茎的衰老，表明茎在这方面是自主的。一个具有异常高叶绿素和氮含量的带环茎保持较低的碳氮 (C/N) 比，并且与其他带环茎不同，没有表现出早期衰老或枯竭的叶绿素水平，这表明响应取决于基因型或其碳和氮状态。代谢物分析强调三羧酸 (TCA) 循环、水杨酸途径和氧化还原稳态参与环带诱导的衰老调节。我们提出，被破坏的汇源关系和 C/N 状态可以通过 TCA 循环和植物激素信号提供线索，以覆盖环带茎中秋季衰老的物候控制。本文受版权保护。版权所有。