An incubation method to determine the age of available nonstructural carbon in woody plant tissues
An incubation method to determine the age of available nonstructural carbon in woody plant tissues
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确定木本植物组织中可用非结构碳年龄的培养方法
DOI：
10.1093/treephys/tpad015
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发表时间：
2023
期刊：
影响因子：
4
通讯作者：
Landhäusser, ed., Simon
中科院分区：
文献类型：
--
作者：
Peltier, Drew M. P.;Lemoine, Jim;Ebert, Chris;Xu, Xiaomei;Ogle, Kiona;Richardson, Andrew D.;Carbone, Mariah S.;Landhäusser, ed., Simon
非结构碳的放射性碳（∆14C）测量可以推断储存的光合产物（如糖、淀粉）的年龄和周转时间，其中树木中最大的光合产物库位于主孔中。由于基于提取的方法存在潜在问题，我们引入了一种通过呼吸二氧化碳捕获非结构碳的∆14C的培养方法。在这项研究中，我们比较了从这些孵育中获得的∆14C与从成熟的颤杨（Populus tremuloides micx）中提取的∆14C。为了了解任何可能的∆14C差异，两种方法的产率也以苯酚-硫酸浓度法为基准。我们发现，孵育过程捕获的糖和淀粉碳不到100%，回收率从心材的3%到浅边材的85%不等。然而，提取率普遍过高（平均预期糖碳含量为273±101%，最高可达480%），其中糖占提取的可溶性碳的比例不到一半，表明特异性很差。虽然可溶性和不可溶性非结构碳的分离表面上是基于提取方法的优势，但也有证据表明，在提取中，这两部分的分离效果很差。边材中呼出的co2的∆14C和提取物产生的∆14C相似，而心材和树皮中提取物产生的∆14C（较老的碳）相对较高。由于产量和∆14C差异在老组织中最大，因此孵育可以更好地捕获实际代谢可用的非结构碳的∆14C。也就是说，我们建议提取包括来自死亡组织或细胞的与代谢无关的碳，以及既不是糖也不是淀粉的碳。相比之下，通过提取捕获的非结构性碳必须呼吸才能测量。因此，我们认为活体组织孵育是一种潜在可行、廉价且通用的方法，可以研究代谢相关（可用）非结构碳的∆14C。
Radiocarbon (∆14C) measurements of nonstructural carbon enable inference on the age and turnover time of stored photosynthate (e.g., sugars, starch), of which the largest pool in trees resides in the main bole. Because of potential issues with extraction-based methods, we introduce an incubation method to capture the ∆14C of nonstructural carbon via respired CO2. In this study, we compared the ∆14C obtained from these incubations with ∆14C from a well-established extraction method, using increment cores from a mature trembling aspen (Populus tremuloides Michx). To understand any potential ∆14C disagreement, the yields from both methods were also benchmarked against the phenol-sulfuric acid concentration assay. We found incubations captured less than 100% of measured sugar and starch carbon, with recovery ranging from ~ 3% in heartwood to 85% in shallow sapwood. However, extractions universally over-yielded (mean 273 ± 101% expected sugar carbon; as high as 480%), where sugars represented less than half of extracted soluble carbon, indicating very poor specificity. Although the separation of soluble and insoluble nonstructural carbon is ostensibly a strength of extraction-based methods, there was also evidence of poor separation of these two fractions in extractions. The ∆14C of respired CO2and ∆14C from extractions were similar in the sapwood, whereas extractions resulted in comparatively higher ∆14C (older carbon) in heartwood and bark. Because yield and ∆14C discrepancies were largest in old tissues, incubations may better capture the ∆14C of nonstructural carbon that is actually metabolically available. That is, we suggest extractions include metabolically irrelevant carbon from dead tissues or cells, as well as carbon that is neither sugar nor starch. In contrast, nonstructural carbon captured by extractions must be respired to be measured. We thus suggest incubations of live tissues are a potentially viable, inexpensive and versatile method to study the ∆14C of metabolically relevant (available) nonstructural carbon.