南极低温植物促生菌筛选及促生功能评价

Screening and evaluation of plant-growth-promoting effect of Antarctic psychrotrophs

摘要:

【背景】国家农业绿色发展和乡村振兴战略中，微生物肥料不可或缺。低温适应型菌株对于研制耐低温、抗冷害胁迫的微生物肥料具有重要意义。【目的】从南极耐冷菌中筛选具有解磷、解硅、合成铁载体和吲哚-3-乙酸(indole-3-acetic acid, IAA)能力的低温植物促生菌(plant growth-promoting bacteria, PGPB)，通过盆栽试验验证和评估低温PGPB菌剂的促生能力，为低温微生物肥料的开发和应用提供优质的菌种资源。【方法】分别使用国际植物研究所磷酸盐生长培养基(National Botanical Research Institute’s phosphate growth medium, NBRIP)、硅酸盐培养基、铬天青(chrome azurol S, CAS)培养基及R2A培养基筛选出具有解磷、解硅、合成铁载体和产IAA多重促生功能的菌株，制备成复合菌剂，并通过矮生番茄盆栽试验评估该复合菌剂的促生效果。【结果】筛选获得6株促生功能多样的南极耐冷菌，其中，明显分开泛菌(Pantoea eucrina) DA-1和马氏副球菌(Paracoccus marcusii) CC-25具有较强的解磷和解硅能力(>85.20 µg/mL)以及良好的铁载体和IAA合成能力，菌株DA-1解磷能力最强，达到105.03 µg/mL；霍氏肠杆菌(Enterobacter hormaechei) GW4-59和圆孢芽孢八叠球菌(Sporosarcina globispora) Z1-38具备3个促生指标，菌株GW4-59具有较强的解磷、解硅和IAA合成能力(>93.12 µg/mL)，解硅能力最强，达到160.50 µg/mL；菌株Z1-38具有解硅、铁载体和IAA合成能力，铁载体合成率为57.64%；佩尔加米诺假单胞菌(Pseudomonas pergaminensis) ZS5-60和南极假单胞菌(Pseudomonas antarctica) ZS9-60具备2个促生指标，菌株ZS5-60具有较强的解磷和解硅能力(>82.22µg/mL)，菌株ZS9-60的铁载体和IAA合成能力较强，IAA产量为116.71 µg/mL。盆栽试验结果表明6株低温PGPB制备的复合菌剂能够显著促进番茄的生长，番茄发芽率、株高、茎粗、根鲜重和结果数分别增加了54.0%、22.3%、29.2%、30.4%和66.0%。【结论】南极环境蕴含丰富的低温PGPB资源，制备的低温复合菌剂可促进番茄生长和发育，为研制适合高纬度农业区及抗低温冷害的微生物肥料提供了优质菌种资源和实践基础。

Abstract:

[Background] In the national strategies for green agricultural development and rural revitalization, microbial fertilizers are indispensable. Strains adapting to low temperature play a crucial role in developing microbial fertilizers tolerant to low temperature and resistant to chilling damage. [Objective] The plant growth-promoting bacteria (PGPB) capable of solubilizing phosphorus and silicon, producing siderophores, and synthesizing indole-3-acetic acid (IAA) were screened from Antarctic psychrophiles. A pot experiment was conducted to evaluate the growth-promoting properties of the inoculant developed from the PGPB isolates. This study aims to provide high-quality bacterial resources for the development and application of low-temperature microbial fertilizers. [Methods] Strains with multiple growth-promoting properties such as solubilizing phosphate and silicon, producing siderophores, and synthesizing IAA were screened with the National Botanical Research Institute’s phosphate growth medium (NBRIP), silicate medium, Chrome azurol S (CAS) medium, and R2A medium. The selected strains were prepared into a composite inoculant, and the plant growth-promoting effects of the composite inoculant were evaluated by a pot experiment with dwarf tomato plants. [Results] Six strains of Antarctic cold-adapted PGPB with diverse plant growth-promoting properties were obtained. Among them, Pantoea eucrina DA-1 and Paracoccus marcusii CC-25 showed excellent phosphorus- and silicon-solubilizing abilities (>85.20 μg/mL) and high siderophore and IAA production. Especially, DA-1 possessed the strongest phosphorus-solubilizing ability (105.03 μg/mL). Enterobacter hormaechei GW4-59 and Sporosarcina globispora Z1-38 exhibited three growth-promoting properties. Specifically, GW4-59 was capable of solubilizing phosphorus and silicon and synthesizing IAA (>93.12 μg/mL), with an excellent silicon-solubilizing ability (160.50 μg/mL); Z1-38 had the abilities to solubilize silicon and synthesize siderophores and IAA, with the siderophore synthesis rate reaching 57.64%. Pseudomonas pergaminensis ZS5-60 and Pseudomonas antarctica ZS9-60 exhibited two growth-promoting properties. Specifically, ZS5-60 possessed strong phosphorus and silicon-solubilizing abilities (>82.22 μg/mL); ZS9-60 had exceptional siderophore- and IAA-synthesizing abilities, with the IAA yield as high as 116.71 μg/mL. The results of the pot experiment showed that the composite inoculant significantly promoted the growth of tomato plants, increasing the germination rate, plant height, stem diameter, root fresh weight, and number of fruits by 54.0%, 22.3%, 29.2%, 30.4%, and 66.0%, respectively. [Conclusion] The Antarctic environment is rich in PGPB resources, and the prepared low-temperature composite bacterial inoculant can promote the growth and development of tomato plants, which has the potential to be applied in low-temperature agricultural areas and provides elite strain resources for the development of low-temperature microbial fertilizers.