Carbone Mariah S, Czimczik Claudia I, Keenan Trevor F, Murakami Paula F, Pederson Neil, Schaberg Paul G, Xu Xiaomei, Richardson Andrew D
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA.
New Phytol. 2013 Dec;200(4):1145-55. doi: 10.1111/nph.12448. Epub 2013 Aug 27.
The allocation of nonstructural carbon (NSC) to growth, metabolism and storage remains poorly understood, but is critical for the prediction of stress tolerance and mortality. We used the radiocarbon ((14) C) 'bomb spike' as a tracer of substrate and age of carbon in stemwood NSC, CO2 emitted by stems, tree ring cellulose and stump sprouts regenerated following harvesting in mature red maple trees. We addressed the following questions: which factors influence the age of stemwood NSC?; to what extent is stored vs new NSC used for metabolism and growth?; and, is older, stored NSC available for use? The mean age of extracted stemwood NSC was 10 yr. More vigorous trees had both larger and younger stemwood NSC pools. NSC used to support metabolism (stem CO2 ) was 1-2 yr old in spring before leaves emerged, but reflected current-year photosynthetic products in late summer. The tree ring cellulose (14) C age was 0.9 yr older than direct ring counts. Stump sprouts were formed from NSC up to 17 yr old. Thus, younger NSC is preferentially used for growth and day-to-day metabolic demands. More recently stored NSC contributes to annual ring growth and metabolism in the dormant season, yet decade-old and older NSC is accessible for regrowth.
非结构性碳（NSC）在生长、代谢和储存之间的分配情况仍知之甚少，但对于预测植物的抗逆性和死亡率至关重要。我们利用放射性碳（¹⁴C）“核弹峰值”作为示踪剂，来研究成熟红枫树茎干NSC中碳的底物和年龄、茎干释放的二氧化碳、树木年轮纤维素以及采伐后再生的树桩萌条中的情况。我们探讨了以下问题：哪些因素影响茎干NSC的年龄？储存的NSC与新的NSC用于代谢和生长的比例是多少？以及，较老的、储存的NSC是否可供使用？提取的茎干NSC的平均年龄为10年。生长更旺盛的树木具有更大且更年轻的茎干NSC库。在春季树叶出现之前，用于支持代谢（茎干二氧化碳）的NSC年龄为1 - 2年，但在夏末反映的是当年的光合产物。树木年轮纤维素的¹⁴C年龄比直接的年轮计数大0.9年。树桩萌条由年龄达17年的NSC形成。因此，较年轻的NSC优先用于生长和日常代谢需求。最近储存的NSC在休眠季节对年轮生长和代谢有贡献，但十年及更老的NSC可用于再生。
