新疆农业大学学报

为拓展具有增强作物耐盐能力的植物根际促生菌资源，本研究以黄瓜品种‘津优401’为供试材料，从75 mmol/L NaCl胁迫后的黄瓜幼苗根际土壤中分离筛选高效促生耐盐细菌。通过盆栽接种试验，待幼苗生长至两叶一心时，设置4个不同处理，无菌水(CK)、菌株Rh72(Rh72)、无菌水+75.0 mmol/L NaCl、菌株Rh72+75.0 mmol/L NaCl，探究耐盐细菌Rh72对盐胁迫下黄瓜幼苗生长及耐盐能力的调控效应。从盐处理15 d的黄瓜根际土壤中分离纯化得到188株细菌，经种子萌发试验共筛选得到11株具有促生耐盐能力的细菌，其中细菌Rh72对黄瓜种子萌发的促生耐盐能力最强，经邻位连接法构建系统发育树，细菌分离株Rh72被鉴定为微杆菌属(Microbacterium)。盆栽试验表明，盐处理下接种耐盐细菌Rh72较未接种相比，植株株高增加92.29%、生物量增加63.61%、根系活力和叶绿素a含量分别显著增加61.60%和19.73%(P<0.05)，叶片电解质渗透率显著降低14.28%(P<0.05)，黄瓜叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性分别显著增加51.47%、21.00%和51.85%(P<0.05)，脯氨酸(Pro)含量显著提高48.03%(P<0.05)，超氧阴离子(O₂^·-)、过氧化氢(H_2O₂)和丙二醛(MDA)含量分别显著下降4.10%、8.16%和28.39%(P<0.05)。综上，耐盐细菌Rh72可通过提高黄瓜幼苗生物量、促进黄瓜幼苗体内渗透物积累、提高抗氧化酶活性和降低MDA含量等途径增强黄瓜幼苗对盐胁迫的抗性。

To expand the resources of plant growth-promoting rhizobacteria capable of enhancing the salt tolerance of crops. In this study, the cucumber variety ‘Jinyou 401’ was used as the test material. From the rhizosphere soil of cucumber seedlings under 75 mmol/L NaCl stress,highly efficient pro-growth salt-tolerant bacteria were isolated and screened. Through pot inoculation test,when the seedlings grew to two leaves and one heart,four different treatments were set up,sterile water(CK),strain Rh72(Rh72),sterile water+75. 0 mmol/L NaCl,strain Rh72+75. 0 mmol/L NaCl,to explore the regulation effect of salt-tolerant bacteria Rh72 on the growth and salt tolerance of cucumber seedlings under salt stress. A total of 188 bacterial strains were isolated and purified from the rhizoidal soil of cucumbers treated with salt for 15 days. Through seed germination tests,11 bacterial strains with promoting growth and salt tolerance were screened out. Among them, bacterial Rh72 had the strongest promoting growth and salt tolerance for cucumber seeds. Phylogenetic trees were constructed by the adjacent connection method. The bacterial isolate Rh72 was identified as belonging to the genus Microbacterium. The pot experiment demonstrated that compared with the untreated group,the inoculated group showed a 92. 29% increase in plant height,a 63. 61% increase in biomass,a significant 61. 60% increase in root vitality and a 19. 73% increase in chlorophyll a content(P<0. 05),a significant 14. 28% reduction in leaf electrolyte permeability(P<0. 05),a significant 51. 47% increase in superoxide dismutase(SOD) activity,a 21. 00% increase in peroxidase(POD) activity and a 51. 85% increase in catalase(CAT) activity(P<0. 05),a significant 48. 03% increase in proline content(P<0. 05),and a significant 4. 10% decrease in superoxide anion(O₂^·-),8. 16% decrease in hydrogen peroxide(H_2O₂) and 28. 39% decrease in malondialdehyde(MDA) content(P<0. 05). In conclusion,the salt-tolerant bacterium Rh72 can enhance the resistance of cucumber seedlings to salt stress by increasing the biomass of cucumber seedlings,promoting the accumulation of osmotic substances in the seedlings, enhancing the activity of antioxidant enzymes,and reducing the content of MDA.