Rhizosphere colonization by plant growth-promoting rhizobacteria (PGPR) facilitates the ability of PGPR to promotes plant growth and health. Among the rhizosphere microbial communities, the dominant PGPR strains should be tapped to analyze their growth-promoting mechanism, and then promote the development and utilization of related agricultural products. In the current study, Bacillus velezensis SX13, Bacillus paralicheniformis SX21, and Bacillus tequilensis SX31, which can dissolve inorganic and organic phosphorus and produce auxin (IAA; except B. tequilensis SX31), were isolated from cucumber rhizosphere. Three weeks after the strains were separately inoculated into the rhizosphere of cucumber plants, the plants treated with the three strains showed improved root structures, photosynthetic parameters, increased growth rate, and high degree of biomass accumulation, compared with the control plants. Plants inoculated with B. velezensis SX13 had the highest seedling growth rate. Experiment using different inoculation doses was conducted. Results showed that B. velezensis SX13 promoted the absorption of elements by the roots and the transport of these elements to the shoots by improving the root structures and up-regulating the expression of CsNRT1 subfamily genes in the roots. Increases in element absorption and transport rates promoted photosynthesis and the activities of enzymes related to carbon metabolism (including ribulose-1,5-bisphosphate carboxylase/oxygenase, sucrose phosphate synthase, phosphoenolpyruvate carboxylase, ribulose-1,5-bisphosphate carboxylase/oxygenase activase, and fructose-l.6-bisphosphate aldolase) and nitrogen metabolism (including nitrate reductase, glutamine synthase, glutamine-2-oxoglutarate aminotransferase, and glutamate dehydrogenase) in the leaves. In addition, the levels of glucose, sucrose, fructose, soluble proteins, and amino acids increased in the leaves. Induced by B. velezensis SX13, increase in photosynthetic metabolism promoted biomass and element accumulation in the roots and shoots and significantly improved fruit quality and yield. However, a dose effect was observed in the case of B. velenzensis SX13 at the doses assayed in this work.

植物生长促进根际细菌 (PGPR) 的根际定殖有助于 PGPR 促进植物生长和健康的能力。在根际微生物群落中，应挖掘优势PGPR菌株，分析其促生机制，进而促进相关农产品的开发利用。在目前的研究中，Bacillus velezensis SX13、Bacillus paralicheniformis SX21、Bacillus tequilensis SX31，可以溶解无机和有机磷并产生生长素（IAA；B. tequilensis除外）SX31)，从黄瓜根际分离。将菌株分别接种到黄瓜植物的根际3周后，与对照植物相比，用这三种菌株处理的植物的根结构、光合参数、生长速率和生物量积累程度均有所提高。接种B. velezensis SX13 的植物具有最高的幼苗生长率。进行了使用不同接种剂量的实验。结果表明，B. velezensis SX13通过改善根系结构和上调CsNRT1的表达，促进根系对元素的吸收和这些元素向枝条的运输。根中的亚家族基因。元素吸收和转运速率的增加促进了光合作用和与碳代谢相关的酶的活性（包括 1,5-二磷酸核酮糖羧化酶/加氧酶、蔗糖磷酸合酶、磷酸烯醇丙酮酸羧化酶、1,5-二磷酸核酮糖羧化酶/加氧酶活化酶、果糖-1.6-二磷酸醛缩酶）和氮代谢（包括硝酸还原酶、谷氨酰胺合酶、谷氨酰胺-2-氧代戊二酸氨基转移酶和谷氨酸脱氢酶）。此外，叶片中葡萄糖、蔗糖、果糖、可溶性蛋白质和氨基酸的含量也有所增加。由B. velezensis诱导SX13，光合代谢的增加促进了根和芽的生物量和元素积累，显着提高了果实品质和产量。然而，在本工作中测定的剂量下，在B. velenzensis SX13的情况下观察到剂量效应。