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https://www.researchgate.net/profile/Yanliang-Wang
原文链接：
https://link.springer.com/article/10.1007/s11104-024-06929-8
在全球范围内，土壤植物可吸收磷含量低（缺磷）普遍存在于森林生态系统中，尤其在热带、亚热带和温带阔叶林中，严重影响植物生长发育。植物根际羧酸阴离子（小分子有机酸阴离子）可以活化土壤磷，提高土壤有效磷含量，进而促进植物磷吸收，根系分泌羧酸是许多植物应对磷缺乏的一种重要策略。此外，菌根植物也可通过与菌根真菌共生促进植物磷吸收，但这种共生可能会因为碳效益权衡（trade-offs）导致根系分泌羧酸减少。因此，研究根际羧酸盐含量对理解植物群落中不同植物应对低磷胁迫的适应性策略具有重要意义。然而，在野外条件下采集、定性和定量分析根际分泌物仍面临诸多挑战。
近年来，多个研究表明植物叶片锰含量可以作为根际羧酸盐含量的一种指示指标。在Plant and Soil最近在线发表的一篇文章中 点击阅读，来自西澳大利亚大学的Yan Li及其合作者的研究发现，与土壤磷含量较高的中国北方森林相比，中国南方低磷森林中的植物叶片锰（Mn）浓度更高，尽管北方森林土壤锰含量更高。该研究揭示了中国森林生态系统植物群落中根际羧酸盐含量与叶片锰浓度之间的潜在关系，并表明许多植物包括菌根植物，可能采用了一种共同的策略—根系分泌羧酸来应对低磷胁迫。
尽管这种策略在不同植物间存在巨大的种间差异，以及根际羧酸盐促进植物叶片锰积累的分子机制仍不清楚，该研究为评估森林生态系统中的植物根际羧酸盐含量提供了一种简便、可靠的研究方法。将来，结合便携式X射线荧光光谱仪对干燥植物成熟叶片（如植物标本）中的锰含量进行无损分析，研究人员能够以快速且低成本的方式大量评估不同环境条件下多种植物的根系羧酸分泌，以理解野外自然条件下植物磷获取策略。
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图 1. 利用叶片锰含量评估根际羧酸盐含量的原理与应用图示。土壤有效磷含量或者植物组织总磷浓度低时，促进根系分泌羧酸并调控植物根系与土壤微生物互作，土壤理化性质、微生物活动以及根系羧酸分泌量共同决定了植物根际“有效”羧酸盐含量，进而调控土壤磷与锰的活化，活化的锰被根系吸收后转运到叶片（a）。在野外条件下，可以通过两个简单的步骤评估植物根际羧酸盐含量：1取样成熟叶片并烘干，2 用手持式X射线荧光分析仪分析叶片锰含量（b）。如果有必要且可操作，获取植物种子在实验室条件下水培或者盆栽收集根系分泌物进一步验证（c）。Phosphorus (P) limitation of aboveground plant production is globally widespread. In forest ecosystems, P limitation mainly occurs in tropical, subtropical, and temperate broadleaved forests, representing a larger area than that exhibiting nitrogen limitation in global forests. Root exudation of carboxylates is widely accepted as a key strategy in mobilizing less-available soil P, as carboxylates can occupy sorption sites on soil minerals that might otherwise bind organic and inorganic P, change mineral dissolution rates, and provide carbon sources for P-mobilizing soil microorganisms. Thus it is of significant importance to study root carboxylate release.However, sampling and quantitative and qualitative determination of root exudates under field conditions faces various challenges. Recently, multiple studies have demonstrated that manganese (Mn) concentration in mature leaves may serve as a proxy for rhizosheath carboxylate concentration. A newly online published paper in Plant and Soil, by Yan and co-authors, shows that leaf Mn concentration ([Mn]) was higher in P-limited forests of southern China than in forests of northern China that exhibit higher soil [P]. This study revealed the potential relationships between rhizosheath carboxylates and leaf [Mn] in the studied Chinese flora, and indicates a potential common strategy (i.e. root carboxylate exudation) among plants, including many mycorrhizal plants, in P-limited forests. Despite the fact that there is great variation among plant species, and the molecular basis underlying the positive correlation between plant Mn uptake and root release of carboxylates remains largely unexplored, this study has paved the road for an easy and reliable way to assess rhizosheath carboxylates in forest ecosystems.In future, in combination with the handheld X-ray fluorescence spectroscopy system that enables non-destructive analysis of [Mn] in dried mature leaves (e.g., herbarium specimens), researchers are able to estimate the patterns of root-released carboxylates for a broad range of plant species under various environmental conditions, in an easy, rapid and low-costs way.长按或扫码直达原文：
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