三种蓝莓根际细菌的分离及其对蓝莓苗生长发育的影响

Bacteria isolated from rhizosphere soils of three blueberry varieties affect the growth and development of blueberry seedlings

摘要:

【目的】从3种蓝莓根际土壤中分离细菌，探究蓝莓根际土壤细菌多样性，并筛选具有产酸、促生长、抑菌性能的菌株，为蓝莓专用微生物肥料的研究提供优质菌株资源和理论基础。【方法】选用5种培养基分离3种蓝莓根际土壤细菌，并进行16S rRNA基因测序和系统发育分析。筛选产酸、产吲哚-3-乙酸（indole-3-acetic acid，IAA）和铁载体、固氮、溶磷和抑制灰葡萄孢生长的菌株，挑选最适菌株制备菌剂进行蓝莓苗盆栽实验验证促生能力，并检测菌剂对蓝莓元素吸收和根际土壤肥力的影响。【结果】从3种蓝莓根际土壤分离得到124株细菌，挑选70株代表性菌株进行16S rRNA基因测序，分布于3个门21个属，其中芽孢杆菌属（Bacillus）、假单胞菌属（Pseudomonas）、链霉菌属（Streptomyces）和红球菌属（Rhodococcus）为优势分离菌群。代表性菌株中，21.4%的菌株能产酸，21.4%的菌株产吲哚-3-乙酸，47.1%的菌株具有固氮潜力，65.7%的菌株具有解磷能力，14.3%的菌株能产铁载体。少量菌株同时具有产酸、产IAA、固氮、解磷和抑菌等能力。选取具有产酸和多种促生特征的菌株绿针假单胞菌CSM-70和双鱼假单胞菌CSM-129进行盆栽蓝莓苗处理，发现2株菌均能显著促进蓝莓苗的生长发育并调控根际土壤pH，其中菌株CSM-70处理还显著促进了蓝莓叶片氮、磷元素的吸收，提升了土壤速效钾、碱解氮的含量。【结论】蓝莓根际细菌多样性高且蕴藏着丰富的促生长菌株，绿针假单胞菌CSM-70和双鱼假单胞菌CSM-129能够促进蓝莓苗生长、调控根际土壤pH和肥力，并促进植株养分吸收，具有蓝莓专用微生物菌剂研制与应用的潜力。

Abstract:

[Objective] We isolated bacteria from the rhizosphere soils of three blueberry varieties, explored the bacterial diversity, and screened out the strains with acid-producing, plant growth-promoting, and antifungal properties, aiming to provide high-quality strain resources and a theoretical basis for the research on blueberry-specialized microbial fertilizers. [Methods] Five different media were used to isolate the bacteria from rhizosphere soils, and 16S rRNA gene sequencing and phylogenetic analysis were performed. The strains capable of producing acid, indole-3-acetic acid (IAA), and siderophores, fixing nitrogen, solubilizing phosphorus, and inhibiting the growth of Botrytis cinerea were screened out. The suitable strains with excellent properties were selected and then inoculated in blueberry seedlings cultivated in pots. The effects on the growth and element absorption of the seedlings and fertility of rhizosphere soil were examined. [Results] A total of 124 strains were isolated from the rhizosphere soils of three blueberry varieties. Seventy representative strains were selected for 16S rRNA gene sequencing, belonging to 21 genera of 3 phyla, among which Bacillus, Pseudomonas, Streptomyces, and Rhodococcus were the dominant bacteria. Among the representative strains, 21.4%, 21.4%, 47.1%, 65.7%, and 14.3% could produce acids, produce IAA, fix nitrogen, solubilize phosphorus, and secrete siderophores, respectively. A few strains displayed the abilities of producing acids and IAA, fixing nitrogen, solubilizing phosphorus, and inhibiting B. cinerea simultaneously. Pseudomonas chlororaphis CSM-70 and Pseudomonas piscium CSM-129 with acid-producing and growth-promoting characteristics were selected and inoculated in blueberry seedlings. Both strains significantly promoted the growth and development of blueberry seedlings and regulated the pH of the rhizosphere soil. In addition, strain CSM-70 significantly promoted the absorption of nitrogen and phosphorus in blueberry leaves and increased the content of available potassium and available nitrogen in the soil. [Conclusion] The blueberry rhizosphere soil has high bacterial diversity and harbors abundant plant growth-promoting strains. P. chlororaphis CSM-70 and P. piscium CSM-129 can promote the growth of blueberry seedlings, regulate rhizosphere soil pH and fertility, and promote nutrient absorption, demonstrating the potential of serving as blueberry-specific microbial fertilizers.