Ramírez Verónica, Munive José-Antonio, Cortes Luis, Muñoz-Rojas Jesús, Portillo Roberto, Baez Antonino
Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico.
Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico.
Front Microbiol. 2020 Apr 24;11:741. doi: 10.3389/fmicb.2020.00741. eCollection 2020.
Volatile organic compounds (VOCs) produced by rhizobacteria have been proven to stimulate plant growth during germination and seedling stages. However, the modulating effect of bacterial volatiles on the germination of seeds subjected to heavy metal stress is scarcely studied. In this work, the ability of volatiles released by sp. MH778713 to induce seed dormancy breakage in and seeds were examined. The minimal inhibitory concentration of chromium (Cr) VI that prevents seed germination of and on water-Cr-agar plates was 2500 and 100 mg L, respectively. Remarkably, partitioned Petri-dish co-cultivation of sp. MH778713 and plant seeds under Cr-stress showed the beneficial effect of volatiles emitted by sp. MH778713, helping plant seeds to overcome Cr-stress. Among the metabolites emitted by sp. MH778713, octadecane, heneicosane, 2,4-di-tert-butylphenol, hexadecane, eicosane, octacosane, and tetratriacontane were the most abundant. To confirm that these long-chain compounds produced by sp. MH778713 could be responsible for the seed dormancy breakage, high pure organic compounds (2,4-di-tert-butylphenol, heneicosane, hentriacontane, and tetracosane) were used directly in germination assays of and seeds instead of volatiles emitted by sp. MH778713. All organic compounds allowed and seeds to overcome Cr-toxicity and germinate. The results of this study provide new insight into the role of long-chain bacterial compounds produced by sp. MH778713 as triggers of seed abiotic stress tolerance, surmounting chromium stress and stimulating seedling development.
根际细菌产生的挥发性有机化合物（VOCs）已被证明在种子萌发和幼苗阶段能刺激植物生长。然而，关于细菌挥发物对遭受重金属胁迫种子萌发的调节作用却鲜有研究。在本研究中，检测了sp. MH778713释放的挥发物诱导和种子休眠破除的能力。在水 - 铬 - 琼脂平板上，阻止和种子萌发的六价铬（Cr）的最低抑菌浓度分别为2500和100 mg/L。值得注意的是，在铬胁迫下，将sp. MH778713与植物种子进行分隔培养的培养皿共培养实验表明，sp. MH778713释放的挥发物具有有益作用，能帮助植物种子克服铬胁迫。在sp. MH778713释放的代谢产物中，十八烷、二十一烷、2,4 - 二叔丁基苯酚、十六烷、二十烷、二十八烷和三十四烷含量最为丰富。为了证实sp. MH778713产生的这些长链化合物可能是种子休眠破除的原因，在和种子的萌发试验中直接使用了高纯有机化合物（2,4 - 二叔丁基苯酚、二十一烷、三十一烷和二十四烷），而非sp. MH778713释放的挥发物。所有有机化合物都能使和种子克服铬毒性并萌发。本研究结果为sp. MH778713产生的长链细菌化合物作为种子非生物胁迫耐受性触发因素、克服铬胁迫及刺激幼苗发育的作用提供了新的见解。
