大豆（Glycine max L.）是我国重要的油料作物，具有极高的食用与饲用价值。根瘤菌可通过与大豆形成共生关系满足植物生长的氮素需求。目前，国内对大豆的需求量大幅增加，而产量仅能满足需求的16%，进口依赖度高。我国土地盐渍化问题严重且分布广泛，因其有机质匮乏，严重影响土壤结构稳定性和微生物多样性，还会影响大豆的产量及品质；同时，盐胁迫会影响根瘤菌共生效率。研究发现，促生菌株与根瘤菌共同接种可提高植物的盐胁迫耐受能力，能够利用具有耕地潜力的盐渍土来扩大大豆种植面积。

实验室前期工作发现，在非盐胁迫下，将促生菌株与根瘤菌共同接种至大豆根部能有效提高大豆生物量和根瘤菌共生能力。为进一步探究盐胁迫条件下大豆-根瘤菌-促生菌三者互作的效果及机制，本文以实验室前期从不同地域大豆根瘤内分离得到的内生细菌为供试菌株，筛选盐胁迫下能够提高大豆根瘤菌（Sinorhizobium fredii CCBAU45436）共生效率、促进大豆生长的高效促生菌株，评价其促生效果及机制。

首先，通过促生特性试验筛选出Y11、RHD12和THD10三株在盐胁迫下促生能力较为突出的菌株，均属于肠杆菌属（Enterobacter）。大豆-根瘤菌-促生菌互作试验结果表明，THD10菌株促进大豆植株生长的效果突出。共同接种THD10和CCBAU45436在0.4%（m/V）盐胁迫下较非盐胁迫下对株高、地上部分鲜重和地上部分干重的促生效果分别提高了约2.7%、21.9%和25.9%。共同接种THD10和CCBAU45436后，在非盐胁迫和0.4%（m/V）盐胁迫下与单独接种CCBAU45436相比，结瘤数量分别增加了约72.2%和65.2%，固氮酶活性分别提高了约48.8%和24.9%。

为了验证THD10在自然盐渍土环境下与CCBAU45436共同接种的促生效果，分别选用NJAU-C101和NJAU-C105两个耐盐大豆品种作为供试植物，在江苏省盐城市盐渍土壤进行田间试验。在大豆初花期，共同接种THD10和CCBAU45436与单独接种CCBAU45436相比，两个大豆品种植株的地上部分干重分别提高了约37.3%和30.6%；固氮酶活性分别提高了约68.1%和56.6%；植株叶片中的CAT活性分别提高了约192.0%和45.9%，丙二醛含量分别降低了约10.5%和37.5%。后续采集田间土壤进行盆栽试验，共同接种THD10和CCBAU45436与单独接种CCBAU45436相比两个大豆品种植株的地上部分干重分别提高了约10.0%和16.1%；固氮酶活性分别提高了约38.1%和19.0%；通过超景深体式镜观察发现，共同接种后根瘤形态较大且更为饱满；植株叶片中的H₂O₂含量分别下降了约18.3%和9.6%；脯氨酸含量分别提高了约82.4%和14.7%；NJAU-C105品种中的丙二醛含量降低了约23.6%。上述结果以及主成分分析说明，促生菌株与根瘤菌协同作用，通过降低大豆在盐胁迫下受到的氧化胁迫损伤，提高固氮效率，促进大豆的生长。

采集盆栽植株根际土壤进行微生物组学分析，共同接种THD10和CCBAU45436与单独接种CCBAU45436相比，两个大豆品种在变形菌门（Proteobacteria）和拟杆菌门（Bacteroidota）上的相对丰度均明显增加；属水平上，两个大豆品种的新鞘氨醇杆菌属（Novosphingobium）相对丰度分别提高了约14.3%和63.4%；NJAU-C105大豆品种样品中的Ensifer / Sinorhizobium和Allorhizobium - Neorhizobium - Pararhizobium - Rhizobium相对丰度分别提高了约13.0%和53.8%。NJAU-C105根际土壤中Ensifer / Sinorhizobium的拷贝数相较于单独接种CCBAU45436显著提高了约40.5%；同时，在相互作用网络中发现THD10能够通过与其它类群的微生物协同作用（呈正相关）来间接影响Ensifer / Sinorhizobium的丰度，从而促进根瘤菌在大豆根际富集。

最后，为了探究THD10菌株与CCBAU45436协作促进大豆植株生长的机制，通过建立促生菌突变子文库的方法筛选到两株促生效果显著降低的THD10突变株，并通过随机引物PCR和测序发现这两个菌株的突变位点分别为ipdC、iolE，编码的蛋白分别为吲哚-3-丙酮酸脱羧酶和肌糖-2脱水酶，分别参与IAA的合成及肌醇代谢，说明促生菌株通过不同的方式（激素、碳代谢）提高根瘤菌在盐胁迫下的共生效率。

综上所述，在低盐胁迫条件下，促生菌株Enterobacter sp. THD10的施用在实验室和自然环境条件下都与根瘤菌协同作用从而在大豆上形成更好的共生体系，促进大豆的生长，对于利用微生物间的互作关系提高大豆在盐渍土壤中的产量具有重要的理论意义与实践价值。

Soybean (Glycine max L.) is an important oil crop in China, which has high edible and feed value. Rhizobia can form a symbiotic relationship with soybean to meet the nitrogen needs of plant growth. At present, the domestic demand for soybeans has increased significantly, while the output can only meet 16% of the demand, which leads to a high dependence on imports. The problem of land salinization in China is serious and widely distributed. Due to the lack of organic matter in saline soil, it seriously affects the stability of soil structure and microbial diversity. And saline soil can also affect the yield and quality of soybean and the symbiosis efficiency of rhizobia. Many studies have found that co-inoculation of growth-promoting bacteria with rhizobia can improve the salt stress tolerance of plants. Therefore, it is conducive to expand soybean planting area by utilizing saline soil with arable land potential.

The previous research work has found that co-inoculation of growth-promoting bacteria with rhizobia into the soybean roots can effectively increase soybeanbiomass and symbiosis ability of rhizobia under salt-free stress. In order to further investigate the effect and mechanism of the interaction between soybean, rhizobia and growth-promoting bacteria under salt stress, this study used endophytic bacteria isolated from soybean root nodules in different regions in laboratory preliminary experiments as the test strainsto screen for efficient growth-promoting bacteria that can improve the symbiotic efficiency of Sinorhizobium fredii CCBAU45436 and promote soybean growth under salt stress, and evaluated their growth-promoting effect and mechanism.

Firstly, three strains with outstanding growth-promoting abilities, Y11, RHD12 and THD10, were screened out through growth-promoting characteristics tests. And they all belonged to Enterobacter. In the test of the interaction of soybean, rhizobia and growth-promoting bacteria, THD10 strain showed a more prominent effect on soybean plant growth. Under 0.4%(m/V) salt stress, after co-inoculation THD10 with CCBAU45436, the growth-promoting effects on plant height, fresh weight and dry weight of shoots increased by about 2.7%, 21.9% and 25.9% compared to salt-free stress conditions, respectively. Under salt-free stress and 0.4%(m/V) salt stress conditions, after co-inoculation THD10 with CCBAU45436, the number of nodulations increased by about 72.2% and 65.2%, respectively and the nitrogenase activity increased by about 48.8% and 24.9%, respectively.

In order to verify the growth-promoting effect of THD10 inoculated with CCBAU45436 in natural saline soil, two soybean varieties, NJAU-C101 and NJAU-C105, were selected as test plants and field experiments were carried out in Yancheng City, Jiangsu Province. In the early flowering stage, compared with single inoculation of CCBAU45436, co-inoculation THD10 with CCBAU45436 significantly increased the dry weight of shoot of the two soybean varieties by about 37.3% and 30.6%, respectively. The nitrogen fixation level of CCBAU45436 was significantly increased, by about 68.1% and 56.6%, respectively. The activity of catalase (CAT) in the leaves increased by about 192.0% and 45.9%, respectively. The content of malondialdehyde in leaves significantly decreased by about 10.5% and 37.5%, respectively. Subsequently, field soil was collected for pot experiments to verify the results. Compared with single inoculation of CCBAU45436, co-inoculating THD10 with CCBAU45436 increased the dry weight of shoot by about 10.0% and 16.1%, respectively. The nitrogen fixation level increased by about 38.1% and 19.0%, respectively. And at the same time, through super-depth-of-field microscope observation, it was found that the root nodules were larger and plumper after co-inoculation. The H₂O₂ content in leaves decreased by about 18.3% and 9.6%, respectively. The content of proline in leaves increased by about 82.4% and 14.7%, respectively. The content of malondialdehyde in NJAU-C105 soybean variety was reduced by about 23.6%. These results indicated that the synergistic effect of growth-promoting strains and rhizobia could promote nitrogen fixation and soybean growth by reducing oxidative stress damage under salt stress.

The rhizosphere soil of potted plants was collected for microbiome analysis. Compared with single inoculation of CCBAU45436, after co-inoculating THD10 with CCBAU45436, the relative abundance of Proteobacteria and Bacteroidota in the samples of the two soybean varieties were significantly increased. Meanwhile, the relative abundance of Novosphingobium in the samples of the two soybean varieties was significantly increased by about 14.3% and 63.4%, respectively. The relative abundance of Ensifer / Sinorhizobium and Allorhizobium - Neorhizobium - Pararhizobium - Rhizobium in NJAU-C105 soybean samples increased by about 13.0% and 53.8%, respectively. Compared with single inoculation of CCBAU45436, after co-inoculating, the number of copies of Ensifer / Sinorhizobium in the rhizosphere soil of NJAU-C105 soybean samples was significantly increased by about 40.5%. In the NJAU-C105 soybean variety interaction network, it was found that the application of the growth-promoting bacterium Enterobacter sp. THD10 could indirectly affect the abundance of Ensifer / Sinorhizobium by synergizing with other groups of microorganisms. This can promote the enrichment of rhizobia in the rhizosphere of soybean.

Finally, in order to explore the mechanism of the cooperation between THD10 and CCBAU45436 to promote the growth of soybean plants, two mutant strains with significantly reduced growth-promoting effect were screened by establishing a mutant strain library of growth-promoting bacteria. The mutation sites of the two mutant strains were ipdC and iolE. The indole-3-pyruvate decarboxylase encoded by the ipdC gene is involved in the synthesis of IAA. The myo-inosose-2 dehydratase encoded by the iolE gene is involved in the inositol metabolism pathway. These results indicated that THD10 strains could improve the symbiotic efficiency of rhizobia under salt stress through different ways, including hormone and carbon metabolism.

In summary, under low salt stress conditions, the application of growth-promoting strain Enterobacter sp. THD10 can form excellent interaction systems with soybean rhizobia to promote the growth of soybean in both laboratory and natural environmental conditions. This can help soybeans adapt to salt stress environments and has important theoretical significance and practical value for using microbial interaction to improve the yield of soybean in saline soil.

[1] 陈利云, 张海林, 周志宇. 生物与非生物因素对共生固氮的影响[J]. 草业科学. 2010, 27(006): 64-70.

[2] 李娇, 张宝龙, 赵颖, 等. 内生菌对提高植物抗盐碱性的研究进展[J]. 生物技术通报, 2014(4): 14-18.

[3] 李艳萍, 张敏, 袁梅, 等. 根瘤菌和复合促生菌对大豆结瘤和生长的影响[J]. 大豆科学, 2017, 36(4): 583-591.

[4] 刘冠一. 盐碱胁迫下接种PGPR和根瘤菌对紫花苜蓿生长的影响[D]. 黑龙江: 哈尔滨师范大学, 2017.

[5] 刘娟娟, 郑娇, 高成林, 等. 苹果内生促生真菌筛选及其促生特性[J]. 果树学报, 2022, 40(04): 735-746.

[6] 刘丽, 马鸣超, 姜昕, 等. 根瘤菌与促生菌双接种对大豆生长和土壤酶活的影响[J]. 植物营养与肥料学报, 2015, 21(03): 644-654.

[7] 刘永秀, 张福锁, 毛达如. 根际微生态系统中豆科植物-根瘤菌共生固氮及其在可持续农业发展中的作用[J]. 中国农业科技导报, 1999, 1(4): 28-33.

[8] 潘勇辉. 超级杂交稻产量优势形成的光合生理机制研究[D]. 江苏: 南京农业大学, 2021.

[9] 田燕丹, 贾宪波, 林新坚, 等. 高产过氧化氢酶菌株的鉴定与产酶条件[J]. 福建农业学报, 2016, 31(8): 869-875.

[10] 田振祥, 丁伟, 程茁, 等. 大豆内生细菌的分离及其作用效果研究[J]. 中国农业科技导报, 2022, 24(06): 47-57.

[11] 谢甫绨. 大豆栽培技术[M]. 东北大学出版社, 2010.

[12] 殷继忠, 李亮, 接伟光, 等. 连作对大豆根际土壤细菌菌群结构的影响[J]. 生物技术通报, 2018, 34(01): 230-238.

[13] 姚领爱, 胡之璧, 王莉莉. 植物内生菌与宿主关系研究进展[J]. 生态环境学报, 2010, 19(7): 1750-1754.

[14] 赵龙飞, 徐亚军, 常佳丽. 具ACC脱氨酶活性大豆根瘤内生菌的筛选、抗性及促生作用[J]. 微生物学报, 2016, 56(6): 1009-1021.

[15] 曾昭海, 胡跃高, 陈文新, 等. 共生固氮在农牧业上的作用及影响因素研究进展[J]. 中国生态农业学报, 2006, 14(4): 21-24.

[16] 张晓霞, 马晓彤, 姜瑞波. 根瘤菌分类研究进展及存在的争议[J]. 微生物学通报, 2010, 37(004): 601-606.

[17] 赵叶舟, 王浩铭, 汪自强. 豆科植物和根瘤菌在生态环境中的地位和作用[J]. 农业资源与环境学报, 2013, 2013(4): 7-12.

[18] Afzal I, Shinwari ZK, Sikandar S, et al. Plant beneficial endophytic bacteria: Mechanisms, diversity, host range and genetic determinants[J]. Microbiological Research, 2019, 221: 36-49.

[19] Agrawal M, Archana G. Phenotypic display of plant growth-promoting traits in individual strains and multispecies consortia of plant growth promoting rhizobacteria and rhizobia under salinity stress[J]. Rhizosphere, 2021, 20: 100443.

[20] Amirjani M. Effect of salinity stress on growth, mineral composition, proline content, antioxidant enzymes of soybean[J]. American Journal of Plant Physiology, 2010, 5: 350–360.

[21] Arayankoon T, Schomberg HH, Weaver RW. Nodulation and N2 fixation of guar at high root temperature[J]. Plant Soil, 1990, 126: 209–213.

[22] Aslam F, Ali B. Halotolerant bacterial diversity associated with Suaeda fruticosa (L.) forssk. Improved growth of maize under salinity stress[J]. Agronomy, 2018, 8: 131.

[23] Atieno M, Herrmann L, Okalebo R, et al. Efficiency of different formulations of Bradyrhizobium japonicum and effect of co-inoculation of Bacillus subtilis with two different strains of Bradyrhizobium japonicum[J]. World Journal of Microbiology and Biotechnology, 2012, 28(7): 2541-2550.

[24] Bakhshandeh E, Pirdashti H, Lendeh KS. Phosphate and potassium-solubilizing bacteria effect on the growth of rice[J]. Ecological Engineering, 2017, 103: 164–169.

[25] Bakker PAHM, Pieterse CMJ, de Jonge R, et al. The soil-borne legacy[J]. Cell, 2018, 172(6): 1178-1180.

[26] Battisti I, Ebinezer LB, Lomolino G, et al. Protein profile of commercial soybean milks analyzed by label-free quantitative proteomics[J]. Food Chemisty, 2021, 352: 129299.

[27] Berendsen RL, Pieterse CM, Bakker PA. The rhizosphere microbiome and plant health[J]. Trends in Plant Science, 2012, 17(8): 478-486.

[28] Bharti N, Pandey SS, Barnawal D, et al. Plant growth promoting rhizobacteria Dietzia natronolimnaea modulates the expression of stress responsive genes providing protection of wheat from salinity stress[J]. Scientific Reports, 2016, 6:34768.

[29] Brevin N. Development of the legume root nodule[J]. Annual Review of Cell Biology, 1991, 7: 191–226.

[30] Brockwell J, Bottomley PJ, Thies JE. Manipulation of rhizobia microflora for improving legume productivity and soil fertility: a critical assessment[J]. Plant and Soil, 1995, 174: 143–180.

[31] Cheng M, Fu HM, Mao Z, et al. Motility behavior and physiological response mechanisms of aerobic denitrifier, Enterobacter cloacae strain HNR under high salt stress: Insights from individual cells to populations[J]. Science of the Total Environment, 2024, 914: 170002.

[32] Cordovilla MP, Ocana A, Ligero F, et al. Salinity effects on growth analysis and nutrient composition in four grain legumes-Rhizobium symbiosis[J]. Journal of Plant Nutrition., 1995, 18: 1595–1609.

[33] Das AK, Anik TR, Rahman MM, et al. Ethanol treatment enhances physiological and biochemical responses to mitigate saline toxicity in soybean[J]. Plants (Basel), 2022, 11(3): 272.

[34] de Carvalho RH, da Conceição JE, Favero VO, et al. The co-inoculation of Rhizobium and Bradyrhizobium increases the early nodulation and development of common beans[J]. Journal of Soil Science and Plant Nutrition, 2020, 20(3): 860-864.

[35] Delgado MJ, Garrido JM, Ligero F, et al. Nitrogen fixation and carbon metabolism by nodules and bacteroids of pea plants under sodium chloride stress[J]. Physiologia Plantarum, 1993, 89: 824–829.

[36] Delgado MJ, Ligero F, Lluch C. Effects of salt stress on growth and nitrogen fixation by pea, faba-bean, common bean and soybean plants[J]. Soil Biology and Biochemistry, 1994, 26: 371–376.

[37] Dutta S, Podile AR. Plant growth promoting rhizobacteria (PGPR): the bugs to debug the root zone[J]. Critical Reviews in Microbiology, 2010, 36(3): 232-244.

[38] Egamberdieva D, Berg G, Lindström MK, et al. Alleviation of Salt Stress of Symbiotic Galega officinalis L. (Goat’s Rue) by Co-Inoculation of Rhizobium with Root-Colonizing Pseudomonas[J]. Plant and Soil, 2013, 369: 453-465.

[39] Egamberdieva D, Jabborova D, Berg G. Synergistic interactions between Bradyrhizobium japonicum and the endophyte Stenotrophomonas rhizophila and their effects on growth, and nodulation of soybean under salt stress[J]. Plant and Soil, 2016, 405: 1–11.

[40] Etesami H, Emami S, Alikhani HA. Potassium solubilizing bacteria (KSB): mechanisms, promotion of plant growth, and future prospects-a review[J]. Journal of Soil Science and Plant Nutrition, 2017, 17: 897-911.

[41] Gale F, Valdes C, Ash M. Interdependence of China, United States, and Brazil in soybean trade[R]. USDA, Economic Research Service, 2019.

[42] Gao Y, Han Y, Li X, et al. A salt-tolerant Streptomyces paradoxus D2-8 from rhizosphere soil of Phragmites communis augments soybean tolerance to soda saline-alkali stress[J]. Polish Journal of Microbiology, 2022, 71: 43–53.

[43] Georgiev GL, Atkias CA. Effects of salinity on N2 fixation, nitrogen metabolism and export and diffusive conductance of cowpea root nodules[J]. Symbiosis, 1993, 15: 239–255.

[44] Gill SS, Tuteja N. Reactive oxygen species and antioxidant machinery in abiotic stress tolerance in crop plants[J]. Plant Physiology and Biochemistry, 2010, 48(12): 909-930.

[45] Glick BR. Plant growth-promoting bacteria: mechanisms and applications[J]. Scientifica, 2012.

[46] Goh CH, Veliz Vallejos DF, Nicotra AB, et al. The impact of beneficial plant-associated microbes on plant phenotypic plasticity[J]. Journal of Chemical Ecology, 2013, 39(7): 826-839.

[47] Gou M, Qu Z, Yang X, et al. Effects of biochar on water saving and fertilizer conservation and tomato yield in sandy loam[J]. Transactions of the Chinese Society for Agricultural Machinery, 2014, (01): 143-148.

[48] Hamdia MAES, Shaddad MAK, Doaa MM. Mechanisms of salt tolerance and interactive effects of Azospirillum brasiliense inoculation on maize cultivars grown under salt stress conditions[J]. Plant Growth Regulation, 2004, 44: 165-174.

[49] Hardoim PR, van Overbeek LS, van Elsas JD. Properties of bacterial endophytes and their proposed role in plant growth[J]. Trends in Microbiology, 2008, 16: 463-471.

[50] Hernández JA. Salinity tolerance in plants: Trends and perspectives[J]. International Journal o Molecular Sciences, 2019, 20(10):2408-2416.

[51] Ikeda J, Kobaysahi M, Takahashi E. Salt stress increases the respiratory cost of nitrogen fixation[J]. Journal of Soil Science and Plant Nutrition, 1992, 38: 51–56.

[52] Jha Y, Subramanian RB. Paddy plants inoculated with PGPR show better growth physiology and nutrient content under saline conditions[J]. Chilean Journal of Agricultural Research, 2013, 73: 213-219.

[53] Jijon-Moreno S, Marcos-Jimenez C, Pedraza RO, et al. The ipdC, hisC1 and hisC2 genes involved in indole-3-acetic production used as alternative phylogenetic markers in Azospirillum brasilense[J]. Antonie van Leeuwenhoek, 2015, 107(6): 1501–1517.

[54] Kämpfer P, Lai WA, Arun AB, et al. Paracoccus rhizosphaerae sp. nov., isolated from the rhizosphere of the plant Crossostephium chinense (L.) Makino (Seremban)[J]. International Journal of Systematic and Evolutionary Microbiology, 2012, 62: 2750–2756.

[55] Kamran M, Aasma P, Sunny A, et al. An overview of hazardous impacts of soil salinity in crops, tolerance mechanisms, and amelioration through selenium supplementation[J]. International Journal of Molecular Sciences, 2020, 21(1): 148–276.

[56] Kataria S, Baghel L, Jain M, et al. Magnetopriming regulates antioxidant defense system in soybean against salt stress[J]. Biocatalysis and Agricultural Biotechnology, 2019, 18: 101090.

[57] Keisham M, Mukherjee S, Bhatla SC. Mechanisms of sodium transport in plants-progresses and challenges[J]. International Journal of Molecular Sciences, 2018, 19(3): 647.

[58] Khadri M, Tejera NA, Lluch C. Alleviation of salt stress in common bean (Phaseolus vulgaris) by exogenous abcisic acid supply[J]. Journal of Plant Growth Regulation, 2006, 25: 110–119.

[59] Kohler PR, Choong EL, Rossbach S. The RpiR-like repressor IolR regulates inositol catabolism in Sinorhizobium meliloti[J]. Journal of Bacteriology, 2011, 193(19): 5155-5163.

[60] Krezhova DD, Kirova EB, Yanev TK, et al. Effects of salinity on leaf spectral reflectance and biochemical parameters of nitrogen fixing soybean plants (Glycine max L.)[J]. AIP Conference Proceedings, 2010, 1203: 694–696.

[61] Kulkarni GB, Nayak AS, Sajjan SS, et al. Indole-3-acetic acid biosynthetic pathway and aromatic amino acid aminotransferase activities in Pantoea dispersa strain GPK[J]. Letters in Applied Microbiology, 2013, 56(5): 340–347.

[62] Kumar A, Singh S, Gaurav AK, et al. Plant growth-promoting bacteria: Biological tools for the mitigation of salinity stress in plants[J]. Frontiers in Microbiology, 2020, 11: 1216.

[63] Kumar A, Verma JP. The role of microbes to improve crop productivity and soil health[J]. Ecological Wisdom Inspired Restoration Engineering, 2019, p: 249–265.

[64] Li XF, Li ZQ. What determines symbiotic nitrogen fixation efficiency in rhizobium: recent insights into Rhizobium leguminosarum[J]. Archives of Microbiology, 2023, 205:300.

[65] Liu A, Xiao Z, Wang Z, et al. Galactolipid and phospholipid profile and proteome alterations in soybean leaves at the onset of salt stress[J]. Frontiers in Plant Science, 2021, 12: 644408.

[66] Liu YC, He WS, He JZ, et al. Research progress on improvement and utilization of saline-alkali land[J]. Research in Agricultural Sciences, 2007, 28(2):68-71.

[67] Liu ZP, Wang BJ, Liu YH, et al. Novosphingobium Taihuense sp. nov., a novel aro-matic-compound-degrading bacterium isolated from Taihu Lake, China[J]. International Journal of Systematic and Evolutionary Microbiology, 2005, 55: 1229-1232.

[68] Lou J, Yang L, Wang H, et al. Assessing soil bacterial community and dynamics by integrated high-throughput absolute abundance quantification[J]. PeerJ, 2018, 6: e4514.

[69] Lundberg D, Lebeis S, Paredes S, et al. Defining the core Arabidopsis thaliana root microbiome[J]. Nature, 2012, 488(7):86–90.

[70] Lv JW. Analysis on application of afforestation technical measures in saline-alkali land[J]. Innovation and Application of Science and Technology, 2015, 7:85-185.

[71] Makhalanyane TP, Valverde A, Gunnigle E, et al. Microbial ecology of hot desert edaphic systems[J]. FEMS Microbiology Reviews, 2015, 39(2):203–221.

[72] Martínez-Viveros O, Jorquera MA, Crowley DE, et al. Mechanisms and practical considerations involved in plant growth promotion by rhizobacteria[J]. Journal of Soil Science and Plant Nutrition, 2010, 10(3): 293 - 319.

[73] Miller G, Suzuki N, Ciftci-Yilmaz S, et al. Reactive oxygen species homeostasis and signalling during drought and salinity stresses[J]. Plant Cell and Environment, 2010, 33(4): 453-467.

[74] Munns R, Tester M. Mechanisms of salinity tolerance[J]. Plant Biology, 2008, 59: 651-681.

[75] Munns R. Comparative physiology of salt and water stress[J]. Plant Cell and Environment, 2002, 25: 239–250.

[76] Nascimento FX, Rossi MJ, Soares CRFS, et al. New Insights into 1-Aminocyclopropane-1-Carboxylate (ACC) Deaminase Phylogeny, Evolution and Ecological Significance[J]. Public Library of Science ONE, 2014, 9(6): e99168.

[77] Negrão S, Schmöckel SM, Tester M. Evaluating physiological responses of plants to salinity stress[J]. Annals of Botany, 2017, 119: 1-11.

[78] Olivares J, Bedmar E J, Sanjuán J. Biological nitrogen fixation in the context of global change[J]. Molecular plant-microbe interactions, 2013, 26(5): 486–494.

[79] Otie V, Udo I, Shao Y, et al. Salinity effects on morpho-physiological and yield traits of soybean (Glycine max L.) as mediated by foliar spray with brassinolide[J]. Plants(Basel), 2021, 10(3): 541.

[80] Pan X, Raaijmakers JM, Carrión VJ. Importance of Bacteroidetes in host-microbe interactions and ecosystem functioning[J]. Trends in Microbiology, 2023, 31(9): 959-971.

[81] Pankievicz VCS, Irving TB, Maia LGS, et al. Are we there yet? The long walk towards the development of efficient symbiotic associations between nitrogen-fixing bacteria and nonleguminous crops[J]. BMC Biology, 2019, 17: 99.

[82] Papiernik SK, Grieve CM, Lesch SM, et al. Effects of salinity, imazethapyr, and chlorimuron application on soybean growth and yield[J]. Communications in Soil Science and Plant Analysis, 2005, 36: 951–967.

[83] Parveen P, Anwar-ul-Haq M, Akhtar J, et al. Interactive effect of salinity and potassium on growth, biochemical parameters, protein and oil quality of soybean genotypes[J]. Pakistan Journal of Agricultural Sciences, 2016, 53: 69–78.

[84] Pathan MS, Lee JD, Shannon JG, et al. Recent advances in breeding for drought and salt stress tolerance in soybean[J]. Advances in Molecular Breeding toward Drought and Salt Tolerant Crops, 2007, pp: 739–773.

[85] Peoples MB, Ladha JK, Herridge DF. Enhancing legume N2 fixation through plant and soil management[J]. Plant and Soil, 1995, 174:83–101.

[86] Phang TH, Shao G, Lam HM. Salt tolerance in soybean[J]. Journal of Integrative Plant Biology, 2008, 50: 1196–1212.

[87] Philippot L, Raaijmakers JM, Lemanceau P, et al. Going back to the roots: the microbial ecology of the rhizosphere[J]. Nature Reviews Microbiology, 2013, 11(11): 789-799.

[88] Pieterse CMJ, de Jonge R, Berendsen RL. The soil-borne supremacy[J]. Trends in Plant Science, 2016, 21(3): 171-173.

[89] Prest EI, El-Chakhtoura J, Hammes F, et al. Combining f low cytometry and 16S rRNA gene pyrosequencing: a promising approach for drinking water monitoring and characterization[J]. Water Research, 2014, 63: 179–189.

[90] Props R, Kerckhof F-M, Rubbens P, et al. Absolute quantification of microbial taxon abundances[J]. The ISME Journal, 2017, 11: 584–587.

[91] Qi W, Zhao L. Study of the siderophore-producing Trichoderma asperellum Q1 on cucumber growth promotion under salt stress[J]. Journal of Basic Microbiology, 2013, 53(4): 355-364.

[92] Qu Y, Tang J, Li Z, et al. Soil enzyme activity and microbial metabolic function diversity in soda saline–alkali rice paddy fields of northeast China[J]. Sustainability, 2020, 12: 10095.

[93] Rahman SU, McCoy E, Raza G, et al. Improvement of soybean, a way forward transition from genetic engineering to new plant breeding technologies[J]. Molecular Biotechnology, 2023, 65(2): 162-180.

[94] Rai A, N S, G S, et al. Paracoccus aeridis sp. nov., an indole-producing bacterium isolated from the rhizosphere of an orchid, Aerides maculosa[J]. International Journal of Systematic and Evolutionary Microbiology, 2020, 70(3): 1720-1728.

[95] Rajendran G, Patel MH, Joshi SJ. Isolation and characterization of nodule-associated Exiguobacterium sp. from the root nodules of fenugreek (Trigonella foenum-graecum) and their possible role in plant growth promotion[J]. International Journal of Microbiology, 2012, 2012: 693982.

[96] Rajkumar M, Ae N, Prasad MNV, et al . Potential of siderophore-producing bacteria for improving heavy metal phyto-extraction[J]. Trends in Biotechnology, 2010, 28(3): 142-149.

[97] Reinhold-Hurek B, Hurek T. Life in grasses: diazotrophic endophytes[J]. Trends in Microbiology, 1998, 6: 139–144.

[98] Rengasamy P. Soil salinization[M]. Oxford Research Encyclopedias, Oxford University Press, Oxford, 2016.

[99]Rosenblueth M, Martínez-Romero E. Bacterial endophytes and their interactions with hosts[J]. Molecular Plant-Microbe Interactions, 2006, 19: 827–837.

[100]Sadak MS, El-Hameid A, Asmaa R,et al. Physiological and biochemical responses of soybean (Glycine max L.) to cysteine application under sea salt stress[J]. Bulletin of the National Research Centre, 2020, 44:1.

[101]Saghaï A, Wittorf L, Philippot L, et al. Loss in soil microbial diversity constrains microbiome selection and alters the abundance of N-cycling guilds in barley rhizosphere[J]. Applied Soil Ecology, 2022, 169: 104224.

[102]Sarkar A, Ghosh PK, Pramanik K, et al. A halotolerant Enterobacter sp. displaying ACC deaminase activity promotes rice seedling growth under salt stress[J]. Research in Microbiology, 2018, 169(1): 20-32.

[103]Shaharoon B, Arshad M, Zahir ZA, et al. Performance of Pseudomonas spp.containing ACC - deaminase for improving growth and yield of maize (Zea mays L.) in the presence of nitrogenous fertilizer[J]. Soil Biology and Biochemistry, 2006, 38: 2971-2975.

[104]Sheteiwy MS, Shao H, Qi W, et al. Seed priming and foliar application with jasmonic acid enhance salinity stress tolerance of soybean (Glycine max L.) seedlings[J]. Journal of the Science of Food and Agriculture, 2021, 101(5): 2027-2041.

[105]Shrivastava P, Kumar R. Soil salinity: a serious environmental issue and plant growth promoting bacteria as one of the tools for its alleviation[J]. Saudi Journal of Biological Sciences, 2015, 22: 123-131.

[106]Singleton PW, Bohlool BB. Effect of salinity on nodule formation by soybean[J]. Plant Physiology, 1984, 74: 72-76.

[107]Stevenson FJ , Cole MA . Cycles of soils : carbon, nitrogen, phosphorus, sulfur, micronutrients, 2nd Edition[J]. Humus Chemistry Genesis Composition Reactions, 1999, 135(6): 642.

[108]Streeter JG. Carbohydrate, organic acid, and amino acid composition of bacteroids and cytosol from soybean nodules[J]. Plant Physiology, 1987, 85: 768–773.

[109]Sukweenadhi J, JuKim Y, CheolKoh ES,et al. Paenibacillus yonginensis DCY84T induces changes in Arabidopsis thaliana gene expression against aluminum, drought, and salt stress[J]. Microbiological Research, 2015, 172: 7–15.

[110]Tejera NA, Campos R, Sanjuan J, et al. Effect of sodium chloride on growth, nutrient accumulation, and nitrogen fixation of common bean plants in symbiosis with isogenic strains[J]. Journal of Plant Nutrition, 2005, 28: 1907–1921.

[111]Thies JE, Woomer PL, Singleton PW. Enrichment of Bradyrhizobium spp. populations in soil due to cropping of the homologous host legume[J]. Soil Biology and Biochemistry, 1995, 27: 633–636.

[112]Thilagam R, Hemalatha N. Plant growth promotion and chilli anthracnose disease suppression ability of rhizosphere soil actinobacteria[J]. Journal of Applied Microbiology, 2019, 126(6): 1835-1849.

[113]Tu JC. Effect of salinity on Rhizobium-root-hairs interaction, nodulation and growth of soybean[J]. Canadian Journal of Plant Science, 198, 61: 231–239.

[114]Turner TR, Ramakrishnan K, Walshaw J, et al. Comparative metatranscriptomics reveals kingdom level changes in the rhizosphere microbiome of plants[J]. The ISME Journal, 2013, 7(12): 2248-2258.

[115]Uzoma K C, Inoue M, Andry H, et al. Effect of cow manure biochar on maize productivity under sandy soil condition[J]. Soil Use and Management, 2011, 27(2): 205-212.

[116]Ventosa A, de la Haba RR, Sánchez-Porro C, et al. Microbial diversity of hypersaline environments: a metagenomic approach[J]. Current Opinion in Microbiology, 2015, 25: 80–87.

[117]Vurukonda SS, Vardharajula S, Shrivastava M, et al. Enhancement of drought stress tolerance in crops by plant growth promoting rhizobacteria[J]. Microbiological Research, 2016, 184: 13-24.

[118]Wang Y, Ling X, Ma C, et al. Can China get out of soy dilemma? A yield gap analysis of soybean in China[J]. Agronomy for Sustainable Development, 2023, 43: 47.

[119]Wang Y, Liu W, Feng WW, et al. Nocardia rhizosphaerae sp. nov., a novel actinomycete isolated from the coastal rhizosphere of Artemisia Linn., China[J]. Antonie van Leeuwenhoek, 2015, 108(1): 31-39.

[120]Warembourg FR, Roumet C, Lafont F. Differences in rhizosphere carbonpartitioning among plant species of different families[J]. Plant and Soil, 2003, 256: 347-357.

[121]Wood M, Stanway AP. Myo-Inositol catabolism by Rhizobium in soil: HPLC and enzymatic studies[J]. Soil Biology and Biochemistry, 2001, 33: 375–379.

[122]Woodward AW, Bartel B. Auxin: regulation, action, and interaction[J]. Annals of Botany, 2005, 95: 707–735.

[123]Yang L, Lou J, Wang H, et al. Use of an improved high-throughput absolute abundance quantification method to characterize soil bacterial community and dynamics[J]. Science of the Total Environment, 2018, 633:360–371.

[124]Yang LG. Physical improvement method of saline-alkali land[J]. Heilongjiang Science and Technology Information, 2007, 000(001): 119-119.

[125]Yoshida KI, Yamaguchi M, Ikeda H, et al. The fifth gene of the iol operon of Bacillus subtilis, iolE, encodes 2-keto-myo-inositol dehydratase[J]. Microbiology(Reading), 2004, 150 (Pt3): 571-580.

[126]Younesi O, Baghbani A, Namdari A. The effects of Pseudomonas Fluorescence and Rhizobium Meliloti co-inoculation on nodulation and nineral nutrient contents in alfalfa (Medicago Sativa) under salinity stress[J]. International Journal of Agriculture and Crop Sciences, 2013, 5(14): 1500-1507.

[127]Yu LZ, Luo XS, Liu M, et al. Diversity of ionizing radiation-resistant bacteria obtained from the Taklimakan Desert[J]. Journal of Basic Microbiology, 2015, 55(1): 135-140.

[128]Yu ZP, Lv WH, Sharmin RA, et al. Genetic dissection of extreme seed-flooding Tolerance in a wild soybean PI342618B by linkage mapping and candidate gene analysis[J]. Plants(Basel), 2023, 12(12): 2266.

[129]Zahran HH, Abu-Gharbia MA. Development and structure of bacterial root-nodules of two Egyptian cultivars of Vicia faba L. under salt and water stresses[J]. Bulletin of Faculty of Science-Assiut University, 1995, 24: 1–10.

[130]Zhao H, Chang J, Havlík P, et al. China’s future food demand and its implications for trade and environment[J]. Nature Sustainability, 2021, 4(12): 1042-1051.

[131]Zhou H, Shi H, Yang Y, et al. Insights into plant salt stress signaling and tolerance[J]. Journal of Genetics and Genomics, 2023, 51(1): 16-34.