Mugani Richard, Khalloufi Fatima El, Redouane El Mahdi, Haida Mohammed, Zerrifi Soukaina El Amrani, Campos Alexandre, Kasada Minoru, Woodhouse Jason, Grossart Hans-Peter, Vasconcelos Vitor, Oudra Brahim
Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Av. Prince My Abdellah, P.O. Box 2390, Marrakech 40000, Morocco.
Department of Plankton and Microbial Ecology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Zur Alten Fischerhuette 2, 14775 Stechlin, Germany.
Microorganisms. 2022 Jul 26;10(8):1511. doi: 10.3390/microorganisms10081511.
Research on Plant Growth-Promoting Bacteria (PGPB) has focused much more on rhizospheric bacteria. However, PGPB associated with toxic cyanobacterial bloom (TCB) could enter the rhizosphere through irrigation water, helping plants such as Pisum sativum L. (pea) overcome oxidative stress induced by microcystin (MC) and improve plant growth and nutritional value. This study aimed to isolate bacteria associated with toxic cyanobacteria, test PGPB properties, and inoculate them as a consortium to pea seedlings irrigated with MC to investigate their role in plant protection as well as in improving growth and nutritional value. Two bacterioplankton isolates and one rhizosphere isolate were isolated and purified on a mineral salt medium supplemented with 1000 μg/L MC and identified via their 16S rRNA gene. The mixed strains were inoculated to pea seedlings in pots irrigated with 0, 50, and 100 μg/L MC. We measured the morphological and physiological parameters of pea plants at maturity and evaluated the efficiency of the plant’s enzymatic and non-enzymatic antioxidant responses to assess the role and contribution of PGPB. Both bacterioplankton isolates were identified as Starkeya sp., and the rhizobacterium was identified as Brevundimonas aurantiaca. MC addition significantly (p < 0.05) reduced all the growth parameters of the pea, i.e., total chlorophyll content, leaf quantum yield, stomatal conductance, carotenoids, and polyphenol contents, in an MC concentration-dependent manner, while bacterial presence positively affected all the measured parameters. In the MC treatment, the levels of the pea’s antioxidant traits, including SOD, CAT, POD, PPO, GST, and ascorbic acid, were increased in the sterile pots. In contrast, these levels were reduced with double and triple PGPB addition. Additionally, nutritional values such as sugars, proteins, and minerals (Ca and K) in pea fruits were reduced under MC exposure but increased with PGPB addition. Overall, in the presence of MC, PGPB seem to positively interact with pea plants and thus may constitute a natural alternative for soil fertilization when irrigated with cyanotoxin-contaminated water, increasing the yield and nutritional value of crops.
对植物促生细菌（PGPB）的研究更多地集中在根际细菌上。然而，与有毒蓝藻水华（TCB）相关的PGPB可通过灌溉水进入根际，帮助诸如豌豆（Pisum sativum L.）等植物克服微囊藻毒素（MC）诱导的氧化应激，并改善植物生长和营养价值。本研究旨在分离与有毒蓝藻相关的细菌，测试PGPB特性，并将它们作为一个组合接种到用MC灌溉的豌豆幼苗上，以研究它们在植物保护以及改善生长和营养价值方面的作用。在添加了1000μg/L MC的矿物盐培养基上分离并纯化了两株浮游细菌菌株和一株根际菌株，并通过其16S rRNA基因进行鉴定。将混合菌株接种到用0、50和100μg/L MC灌溉的盆栽豌豆幼苗上。我们测量了豌豆植株成熟时的形态和生理参数，并评估了植物酶促和非酶促抗氧化反应的效率，以评估PGPB的作用和贡献。两株浮游细菌菌株均被鉴定为斯塔基氏菌属（Starkeya sp.），根际细菌被鉴定为橙色短波单胞菌（Brevundimonas aurantiaca）。添加MC以浓度依赖的方式显著（p < 0.05）降低了豌豆的所有生长参数，即总叶绿素含量、叶片量子产率、气孔导度、类胡萝卜素和多酚含量，而细菌的存在对所有测量参数都有积极影响。在MC处理中，无菌盆栽中豌豆的抗氧化特性水平，包括超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）、多酚氧化酶（PPO）、谷胱甘肽S-转移酶（GST）和抗坏血酸，有所增加。相比之下，添加双倍和三倍PGPB后这些水平降低。此外，在MC暴露下豌豆果实中的糖、蛋白质和矿物质（钙和钾）等营养价值降低，但添加PGPB后增加。总体而言，在有MC存在的情况下，PGPB似乎与豌豆植株产生积极相互作用，因此在用受蓝藻毒素污染的水灌溉时，可能构成土壤施肥的天然替代方法，提高作物产量和营养价值。
