Cantarel Amélie A M, Signoret Aymeric, Gervaix Jonathan, Beligon Chiquitta, Béraud Cédric, Boisselet Christelle, Creuzé des Châtelliers Charline, Defour Pauline, Delort Abigaïl, Lacroix Elise, Lobreau Clément, Louvez Enzo, Marais Coralie, Simonin Marie, Piola Florence
Université Claude Bernard Lyon 1, Laboratoire d'Ecologie Microbienne LEM, UMR 5557 CNRS, UMR 1418 INRAE, VetAgro Sup, 69622 Villeurbanne, France.
Université Claude Bernard Lyon 1, Laboratoire des Ecosystèmes et Hydosystèmes Naturels et Anthropisés LEHNA, ENTPE, UMR 5023 CNRS, 69622 Villeurbanne, France.
Ann Bot. 2024 Apr 23;133(4):533-546. doi: 10.1093/aob/mcad174.
The successful plant Fallopia × bohemica presents interesting capacities for control of the soil nitrogen cycle at the adult stage, termed biological inhibition of denitrification (BDI). The BDI strategy allows the plant, via the production of secondary metabolites (procyanidins), to compete with the denitrifying microbial community and to divert nitrate from the soil for its benefit. In this study, we analysed whether seedlings of F. × bohemica can implement BDI at the seedling stage. We also determined whether soil nitrogen availability influences the implementation of BDI and seedling growth.
We sowed achenes of F. × bohemica in soils representing a nitrogen gradient (six treatments) and harvested seedlings after 20 or 40 days of growth. The denitrification and related microbial communities (i.e. functional gene abundances of nirK and nirS), soil parameters (nitrate content and humidity) and plant performance (biomass, growth and root morphology) were determined.
On soil without addition of nitrogen, BDI was observed after 20 days of growth, whereas a stimulation of denitrification was found after 40 days. The increase of soil N content had few effects on the activity and structure of the soil denitrifying community and on the plant biomasses or the relative growth rates. Correlations between plant and microbial parameters were observed after 20 days of growth, reflecting early and strong chemical interactions between plants and the denitrifying community, which decreased with plant growth after 40 days.
This study shows that an early BDI enhances the efficiency of nitrogen acquisition in the first weeks of growth, allowing for a conservative root strategy after 40 days. This switch to a conservative strategy involved resource storage, an altered allocation to above- and below-ground parts and an investment in fine roots. It now seems clear that this storage strategy starts at a very young age with early establishment of BDI, giving this clonal plant exceptional capacities for storage and multiplication.
成功的植物腋花蓼在成年阶段展现出控制土壤氮循环的有趣能力，即反硝化作用的生物抑制（BDI）。BDI策略使植物能够通过产生次生代谢产物（原花青素）与反硝化微生物群落竞争，并将土壤中的硝酸盐转移为自身所用。在本研究中，我们分析了腋花蓼幼苗在幼苗期是否能够实施BDI。我们还确定了土壤氮有效性是否会影响BDI的实施和幼苗生长。
我们将腋花蓼瘦果播种在代表氮梯度的土壤中（六种处理），并在生长20天或40天后收获幼苗。测定了反硝化作用及相关微生物群落（即nirK和nirS功能基因丰度）、土壤参数（硝酸盐含量和湿度）以及植物性能（生物量、生长和根系形态）。
在未添加氮的土壤上，生长20天后观察到BDI，而40天后发现反硝化作用受到刺激。土壤氮含量的增加对土壤反硝化群落的活性和结构以及植物生物量或相对生长速率影响较小。生长20天后观察到植物与微生物参数之间的相关性，反映出植物与反硝化群落之间早期且强烈的化学相互作用，这种相互作用在40天后随着植物生长而减弱。
本研究表明，早期的BDI在生长的最初几周提高了氮获取效率，使得40天后能够采取保守的根系策略。这种向保守策略的转变涉及资源储存、地上和地下部分分配的改变以及对细根的投入。现在很明显，这种储存策略在植物非常幼小时就随着BDI的早期建立而开始，赋予了这种克隆植物非凡的储存和繁殖能力。
