Popržen Tatjana, Antonić Reljin Dragana, Uzelac Branka, Milovančević Marija, Paunović Danijela, Trifunović-Momčilov Milana, Marković Marija, Raspor Martin, Nikolić Ivan, Stanković Slaviša, Radulović Olga
Department of Plant Physiology, Institute for Biological Research "Siniša Stanković" - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia.
Center for Biological Control and Plant Growth Promotion, Faculty of Biology, University of Belgrade, Belgrade, Serbia.
Front Microbiol. 2024 Dec 18;15:1481437. doi: 10.3389/fmicb.2024.1481437. eCollection 2024.
The common duckweed () is a model organism for investigation of plant physiology, especially stress-related responses. Its two physiological characteristics are of special interest: (1) salt-stressed duckweeds may accumulate starch, a precursor for biofuel; (2) duckweeds are associated with various beneficial (plant-growth promoting, PGP) bacterial strains. In this paper, we analyzed the role of two bacterial strains: D1-104/3 and C31-106/3 in regulation of duckweed's growth and antioxidative responses to salt (10 and 100 mM NaCl) and hypothesized that they alleviate salt-induced oxidative stress.
Fresh and dry weight, frond number, photosynthetic pigments, malondialdehyde (MDA) and hydrogen peroxide (HO), ascorbic acid (AsA), proline, total polyphenol (TPC) and starch content, as well as antioxidant capacity and antioxidant enzymatic activity were measured after 14 days. Fluorescence microscopy was used to visualize bacterial presence on duckweeds.
Fluorescence microscope revealed that bacteria colonized all duckweed surfaces. The doubling time of duckweeds inoculated with C31-106/3 was significantly longer. Additionally, at 0 and 10 mM NaCl, this strain decreased chlorosis in duckweeds. Moreover, C31-106/3 increased dry-to-fresh-weight ratio, proline, chlorophyll a, b and carotenoid content at 100 mM, as well as AsA content in plants in NaCl-free medium, while D1-104/3 increased AsA at 100 mM NaCl. Both bacterial strains decreased lipid peroxidation, while C31-106/3 increased and D1-104/3 decreased HO content at 100 mM and 0 mM NaCl, respectively. Bacteria significantly increased TPC and antioxidant capacity at 100 mM NaCl, particularly D1-104/3. After 14 days, the SOD and POX activities were at the same level in all samples. At 100 mM NaCl, CAT activity was increased in all plants.
The results of this study show that two strains had markedly different effects on duckweed: while D1-104/3 supported growth, C31-106/3 prioritized salt stress tolerance in duckweeds.
常见浮萍（）是用于研究植物生理学，特别是与胁迫相关反应的模式生物。它有两个特别令人感兴趣的生理特征：（1）盐胁迫下的浮萍可能积累淀粉，这是生物燃料的前体；（2）浮萍与各种有益的（促进植物生长的，PGP）细菌菌株有关。在本文中，我们分析了两种细菌菌株：D1 - 104/3和C31 - 106/3在调节浮萍生长以及对盐（10和100 mM NaCl）的抗氧化反应中的作用，并假设它们能减轻盐诱导的氧化应激。
14天后测量鲜重和干重、叶状体数量、光合色素、丙二醛（MDA）和过氧化氢（HO）、抗坏血酸（AsA）、脯氨酸、总多酚（TPC）和淀粉含量，以及抗氧化能力和抗氧化酶活性。使用荧光显微镜观察细菌在浮萍上的存在情况。
荧光显微镜显示细菌定殖在浮萍的所有表面。接种C31 - 106/3的浮萍倍增时间明显更长。此外，在0和10 mM NaCl条件下，该菌株减少了浮萍的黄化现象。而且，C31 - 106/3在100 mM时增加了干鲜比、脯氨酸、叶绿素a、b和类胡萝卜素含量，在无NaCl培养基中增加了植物中的AsA含量，而D1 - 104/3在100 mM NaCl时增加了AsA含量。两种细菌菌株都降低了脂质过氧化，而C31 - 106/3在100 mM和0 mM NaCl时分别增加和降低了HO含量。在100 mM NaCl时，细菌显著增加了TPC和抗氧化能力，特别是D1 - 104/3。14天后，所有样品中的超氧化物歧化酶（SOD）和过氧化物酶（POX）活性处于同一水平。在100 mM NaCl时，所有植物中的过氧化氢酶（CAT）活性均增加。
本研究结果表明，两种菌株对浮萍有明显不同的影响：D1 - 104/3促进生长，而C31 - 106/3则优先提高浮萍对盐胁迫的耐受性。
