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

作　　者：李雪梅 姚拓[1] 李昌宁 杨晓蕾 王晚霞 张怡忻 LI Xue-mei;YAO Tuo;LI Chang-ning;YANG Xiao-lei;WANG Wan-xia;ZHANG Yi-xin(Key Laboratory of Grassland Ecosystem,Ministry of Education,College of PratacultureGansu Agricultural University,Lanzhou 730070,China)

机构地区：[1]甘肃农业大学草业学院,草业生态系统教育部重点实验室,甘肃兰州730070

出　　处：《草业学报》2025年第3期134-143,共10页Acta Prataculturae Sinica

基　　金：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);国家牧草产业体系金昌综合试验站(CARS-34)资助。

摘　　要：为进一步挖掘高寒草地野生天蓝苜蓿根瘤菌资源,筛选与宿主植物高效共生的菌株。本研究利用YMA刚果红培养基从野生天蓝苜蓿中分离根瘤菌,通过菌落形态观察、产酸产碱反应结合16S rRNA基因序列分析进行菌株鉴定,原宿主回接验证其促生特性,离体耐酸、耐碱及温度耐受性测定菌株抗逆能力。结果表明:从野生天蓝苜蓿中分离得到4株菌株,菌落形态和产酸产碱结果符合根瘤菌特性,经鉴定菌株GNT1和GNT6为苜蓿中华根瘤菌,菌株GNT2为吉氏副根瘤菌,菌株GNT4为豆根副根瘤菌。4株根瘤菌回接后植株单株结瘤数、株高、根长及植株干重分别是不接种处理的2.06~3.64倍、0.75~3.17倍、0.21~0.38倍和0.55~2.82倍,有效结瘤数和固氮酶活性分别为11.33~18.00个、5.71~10.97μmol C_(2)H_(4)·g^(-1)·h^(-1),不接种处理下根瘤为无效根瘤且不具有固氮酶活性。4株菌株均能在pH为11时生长,以菌株GNT2生长最佳;不同菌株对NaCl耐受能力不同,其中菌株GNT6耐受5%NaCl,且仅菌株GNT6在4℃低温下能够生长,具有在高寒草地应用的潜力。因此,筛选出的苜蓿中华根瘤菌GNT6可作为候选菌株为高寒草地的修复提供优良菌株资源。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 5.71-10.97μmol 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 

分 类 号：S812[农业科学—草业科学]