Cesari Adriana Belén, Paulucci Natalia Soledad, Dardanelli Marta Susana
Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, Córdoba X5804BYA, Argentina.
Instituto de Biotecnología Ambiental y Salud (INBIAS), Consejo Nacional de Investigaciones Científicas y Tecnicas, Rio Cuarto X5800BIA, Argentina.
Plants (Basel). 2025 May 24;14(11):1601. doi: 10.3390/plants14111601.
Peanut ( L.) is one of the most important oilseeds crops worldwide. Through symbiosis with the bacterium sp., peanuts can assimilate atmospheric nitrogen, reducing the need for chemical fertilizers. However, this nitrogen fixation process is highly sensitive to environmental factors that can inhibit the early stages of symbiotic interaction. In this study, we propose the encapsulation of sp. SEMIA6144 and the flavonoid naringin (Nar) in alginate beads to improve flavonoid stability and promote nodulation kinetics in peanuts. Three types of beads were synthesized: A (control, SEMIA6144 only); B (SEMIA6144 induced with 10 µM Nar); and C (SEMIA6144 co-entrapped with 1 mM Nar). Although Nar increased cell mortality (2-fold compared to control) and reduced metabolic activity-particularly at 1 mM-cells in beads B and C responded by altering their membrane fatty acid profile (30% and 55.5% of 18:1, respectively) leading to a reduction in saturated fatty acids (5.8% and 13.1% for 16:0 and 18:0 in B; 11.8% and 21.2% in C). Bacterial release kinetics followed a primarily Fickian diffusion model, with minor matrix-bacteria interactions in Nar-treated beads. Notably, bacterial release in peanut root exudates was 6%, 10%, and 11% higher for beads A, B, and C, respectively, compared to release in physiological solutions. Nar-beads enhanced the formation of curved root hairs, promoted bacterial colonization in root hair zones, and stimulated the appearance of rosette-like structures associated with nodule initiation. In conclusion, encapsulating sp. SEMIA6144 with Nar in beads represents a promising strategy to improve symbiotic nitrogen fixation in peanuts.
花生（Arachis hypogaea L.）是全球最重要的油料作物之一。通过与根瘤菌（Bradyrhizobium sp.）共生，花生能够同化大气中的氮，从而减少对化肥的需求。然而，这种固氮过程对环境因素高度敏感，这些环境因素会抑制共生相互作用的早期阶段。在本研究中，我们提出将根瘤菌SEMIA6144和类黄酮柚皮苷（Nar）包封在海藻酸钠珠中，以提高类黄酮的稳定性并促进花生的结瘤动力学。合成了三种类型的珠子：A（对照，仅含SEMIA6144）；B（用10 μM Nar诱导的SEMIA6144）；和C（与1 mM Nar共包埋的SEMIA6144）。尽管Nar增加了细胞死亡率（与对照相比增加了2倍）并降低了代谢活性，特别是在1 mM时，但B和C珠中的细胞通过改变其膜脂肪酸谱做出反应（分别为18:1的3�%和55.5%），导致饱和脂肪酸减少（B中16:0和18:0分别为5.8%和13.1%；C中为11.8%和21.2%）。细菌释放动力学主要遵循菲克扩散模型，在经Nar处理的珠子中基质与细菌的相互作用较小。值得注意的是，与在生理溶液中的释放相比，珠子A、B和C在花生根分泌物中的细菌释放分别高出6%、10%和11%。含Nar的珠子增强了弯曲根毛的形成，促进了根毛区的细菌定殖，并刺激了与根瘤起始相关的莲座状结构的出现。总之，将根瘤菌SEMIA6144与Nar包封在珠子中是一种有前景的提高花生共生固氮作用 的策略。
