Paponov Martina, Flate Juanita, Ziegler Jörg, Lillo Cathrine, Paponov Ivan A
Division of Food Production and Society, Norwegian Institute of Bioeconomy Resesarch (NIBIO), As, Norway.
Department of Chemistry, Bioscience and Environmental Engineering, University of Stavanger, Stavanger, Norway.
Front Plant Sci. 2023 Jun 2;14:1174151. doi: 10.3389/fpls.2023.1174151. eCollection 2023.
Plants have evolved complex mechanisms to adapt to nutrient-deficient environments, including stimulating lateral root proliferation into local soil patches with high nutrient content in response to heterogeneous nutrient distribution. Despite the widespread occurrence of this phenomenon in soil, the effect of heterogeneous nutrient distribution on the accumulation of secondary compounds in plant biomass and their exudation by roots remains largely unknown. This study aims to fill this critical knowledge gap by investigating how deficiency and unequal distributions of nitrogen (N), phosphorus (P), and iron (Fe) affect plant growth and accumulation of the antimalarial drug artemisinin (AN) in leaves and roots of , as well as AN exudation by roots. Heterogeneous N and P supplies strongly increased root exudation of AN in half of a split-root system exposed to nutrient deficiency. By contrast, exposure to a homogeneous nitrate and phosphate deficiency did not modulate root exudation of AN. This indicates that a combination of local and systemic signals, reflecting low and high nutritional statuses, respectively, were required to enhance AN exudation. This exudation response was independent of the regulation of root hair formation, which was predominantly modulated by the local signal. In contrast to the heterogeneous supply of N and P, heterogeneous Fe supply did not modulate AN root exudation but increased AN accumulation in locally Fe-deficient roots. No modulation of nutrient supply significantly changed the accumulation of AN in leaves. The impact of a heterogeneous nitrate supply on growth and phytochemical composition was also investigated in plants. Unlike in , the uneven N supply did not significantly influence the exudation of secondary compounds in the roots of . However, it did enhance the accumulation of several biologically active compounds, such as hypericin, catechin, and rutin isomers, in the leaves of . We propose that the capacity of plants to induce the accumulation and/or differential exudation of secondary compounds under heterogeneous nutrient supply is both species- and compound-specific. The ability to differentially exude AN may contribute to 's adaptation to nutrient disturbances and modulate allelopathic and symbiotic interactions in the rhizosphere.
植物已经进化出复杂的机制来适应营养缺乏的环境，包括响应异质养分分布，刺激侧根向养分含量高的局部土壤斑块中增殖。尽管这种现象在土壤中广泛存在，但异质养分分布对植物生物量中次生化合物积累及其根系渗出的影响仍然很大程度上未知。本研究旨在通过调查氮（N）、磷（P）和铁（Fe）的缺乏及不均衡分布如何影响青蒿（Artemisia annua）叶片和根系中抗疟药物青蒿素（AN）的植物生长和积累以及根系对AN的渗出，来填补这一关键的知识空白。异质的N和P供应强烈增加了暴露于养分缺乏的分根系统一半中AN的根系渗出。相比之下，暴露于均匀的硝酸盐和磷酸盐缺乏状态并未调节AN的根系渗出。这表明分别反映低营养状态和高营养状态的局部和系统信号的组合是增强AN渗出所必需的。这种渗出反应与根毛形成的调节无关，根毛形成主要受局部信号调节。与N和P的异质供应相反，异质的Fe供应并未调节AN的根系渗出，但增加了局部缺铁根系中AN的积累。养分供应的调节未显著改变青蒿叶片中AN的积累。还研究了异质硝酸盐供应对青蒿植物生长和植物化学成分的影响。与青蒿不同，不均衡的N供应并未显著影响青蒿根系中次生化合物的渗出。然而，它确实增强了青蒿叶片中几种生物活性化合物的积累，如金丝桃素、儿茶素和芦丁异构体。我们提出，植物在异质养分供应下诱导次生化合物积累和/或差异渗出的能力是物种和化合物特异性的。差异渗出AN的能力可能有助于青蒿适应养分干扰并调节根际中的化感和共生相互作用。
