• Despite the ecological and industrial importance of biomass accumulation in wood, the control of carbon (C) allocation to this tissue and to other tree tissues remain poorly understood.
• We studied sucrose synthase (SUS) to clarify its role in biomass formation and C metabolism at the whole tree level in hybrid aspen (Populus tremula × tremuloides). To this end, we analysed source leaves, phloem, developing wood, and roots of SUSRNAi trees using a combination of metabolite profiling, ¹³CO₂ pulse labelling experiments, and long‐term field experiments.
• The glasshouse grown SUSRNAi trees exhibited a mild stem phenotype together with a reduction in wood total C. The ¹³CO₂ pulse labelling experiments showed an alteration in the C flow in all the analysed tissues, indicating that SUS affects C metabolism at the whole tree level. This was confirmed when the SUSRNAi trees were grown in the field over a 5‐yr period; their stem height, diameter and biomass were substantially reduced.
• These results establish that SUS influences C allocation to developing wood, and that it affects C metabolism at the whole tree level.

中文翻译：

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蔗糖合酶决定了正在发育的木材中的碳分配，并改变了白杨整棵树的碳流量。

• 尽管木材中生物质积累的生态和工业重要性，但对这种组织和其他树木组织的碳（C）分配控制的了解仍知之甚少。
• 我们研究了蔗糖合酶（SUS），以阐明其在杂种杨木（Populus tremula  ×  tremuloides）的整棵树中对生物量形成和碳代谢的作用。为此，我们结合了代谢物谱分析，^13个CO ₂脉冲标记实验和长期田间实验，分析了SUSRNAi树的源叶，韧皮部，发育中的木材和根。
• 温室种植的SUSRNAi树表现出温和的茎表型，并降低了木材总C。13^个CO ₂脉冲标记实验表明，所有分析组织中C流量均发生变化，表明SUS影响了整棵树的C代谢。当SUSRNAi树在田间种植5年以上时，这一点得到了证实。它们的茎高，直径和生物量均大大降低。
• 这些结果表明，SUS影响碳在发育中的木材的分配，并影响整个树木水平的碳代谢。