Salomon Sarah, Schilling Marion, Albrieux Catherine, Si Larbi Grégory, Jouneau Pierre-Henri, Roy Sylvaine, Falconet Denis, Michaud Morgane, Jouhet Juliette
Laboratoire Physiologie Cellulaire et Végétale, Université Grenoble Alpes, CNRS, CEA, INRAE, IRIG, Grenoble, France.
Laboratoire Modélisation et Exploration des Matériaux, CEA, Université Grenoble Alpes, IRIG, Grenoble, France.
J Exp Bot. 2025 Feb 25;76(4):980-996. doi: 10.1093/jxb/erae458.
Plants and algae have to adapt to environmental changes and face various stresses that negatively affect their growth and development. One common stress is phosphate (Pi) deficiency, which is often present in the environment at limiting levels. In response to Pi deficiency, these organisms increase Pi uptake and remobilize intracellular Pi. Phospholipids are degraded to provide Pi and are replaced by non-phosphorus lipids, such as glycolipids or betaine lipids. During evolution, seed plants lost the ability to synthesize betaine lipids. By expressing Bta1 genes, which are involved in the synthesis of diacylglyceryl-N,N,N-trimethyl-homoserine (DGTS), from different species, we showed that DGTS can be produced in seed plants. In Arabidopsis, expression of BTA1 under a phosphate starvation-inducible promoter resulted in limited DGTS production without having any impact on plant growth or lipid remodelling. In transient expression systems in Nicotiana benthamiana, leaves were able to accumulate DGTS to up to 30% of their glycerolipid content at a slight expense to galactolipid and phospholipid production. At the subcellular level, we showed that DGTS is absent from plastids and seems to be enriched in endomembranes, inducing endoplasmic reticulum membrane proliferation. Finally, the DGTS synthesis pathway seems to compete with phosphatidylcholine (PC) synthesis via the Kennedy pathway but does not appear to be derived from the PC diacylglycerol backbone and therefore does not interfere with the eukaryotic pathway involved in galactolipid synthesis.
植物和藻类必须适应环境变化，并面临各种对其生长和发育产生负面影响的胁迫。一种常见的胁迫是磷（Pi）缺乏，这种情况在环境中常常处于限制水平。作为对Pi缺乏的响应，这些生物体增加Pi的吸收并重新调动细胞内的Pi。磷脂被降解以提供Pi，并被非磷脂质所取代，例如糖脂或甜菜碱脂。在进化过程中，种子植物失去了合成甜菜碱脂的能力。通过表达来自不同物种的、参与二酰基甘油-N，N，N-三甲基高丝氨酸（DGTS）合成的Bta1基因，我们证明了DGTS可以在种子植物中产生。在拟南芥中，在磷饥饿诱导型启动子控制下的BTA1表达导致DGTS产量有限，且对植物生长或脂质重塑没有任何影响。在本氏烟草的瞬时表达系统中，叶片能够积累DGTS，其含量高达甘油脂质含量的30%，而对半乳糖脂和磷脂的产生略有影响。在亚细胞水平上，我们发现质体中不存在DGTS，且其似乎在内膜中富集，从而诱导内质网膜增殖。最后，DGTS合成途径似乎通过肯尼迪途径与磷脂酰胆碱（PC）合成竞争，但似乎并非源自PC二酰甘油主链，因此不会干扰参与半乳糖脂合成的真核途径。
