草业学报2025，Vol.34Issue(3)：134-143,10.DOI:10.11686/cyxb2024163
甘南野生天蓝苜蓿高效共生、抗逆根瘤菌筛选鉴定
Screening and identification of symbiotically efficient and stress-resistant rhizobia of wild Medicago lupulina in Gannan
摘要
Abstract
This research investigated the rhizobacterial resources of wild Medicago lupulina in alpine meadows,by screening for strains exhibiting efficient symbiosis with host plants.YMA Congo red medium was used to isolate rhizobacteria from wild M.lupulina,and strain identification was carried out through colony morphology observation and assessment of acid and alkali production,combined with 16S rRNA gene sequence analysis.Growth-promoting properties were verified by back-inoculation to the original host,and strain resilience was determined by evaluating in vitro acid,alkali and temperature tolerance.Four strains of interest were isolated from wild M.lupulina in this way,designated GNT1,GNT2,GNT4 and GNT6,and the colony morphology and acid and alkali production results were consistent with the characteristics of rhizobia.Strains GNT1 and GNT6 were identified as Sinorhizobium meliloti,GNT2 as Pararhizobium giardinii,and GNT4 as Pararhizobium herbae.Compared with a no-inoculation treatment,rhizobium inoculation increased the number of plant nodules by 2.06-3.64 times,the plant height by 0.75-3.17 times,the root length by 0.21-0.38 times and the plant dry weight by 0.55-2.82 times.The effective nodule number and nitrogenase activity under inoculation treatments were 11.33-18.00 nodules per plant and 5.71-10.97 μmol C2H4·g-1·h-1,respectively.The nodules under the non-inoculation treatment were ineffective nodules and did not have nitrogenase activity.The four strains could grow at pH 11,and the strain GNT2 grew best.The strains differed in their tolerance to NaCl.Strain GNT6 could tolerate 5% NaCl,and only strain GNT6 could grow at the low temperature of 4℃.Hence,strain GNT6 was determined to have potential to be applied in alpine grassland,and is identified in this research as a candidate strain to provide improved rhizobial strain resources for the restoration of alpine grassland.关键词
天蓝苜蓿/根瘤菌/抗逆/高效共生Key words
Medicago lupulina/rhizobium/strain resilience/efficient symbiosis引用本文复制引用
李雪梅,姚拓,李昌宁,杨晓蕾,王晚霞,张怡忻..甘南野生天蓝苜蓿高效共生、抗逆根瘤菌筛选鉴定[J].草业学报,2025,34(3):134-143,10.基金项目
甘肃省林业和草原局高寒退化草地植被恢复与土壤改良菌剂研发与示范项目(GSAU-TSYF-2021-011)和国家牧草产业体系金昌综合试验站(CARS-34)资助. （GSAU-TSYF-2021-011）
