【作者】 刘昔辉；

【导师】 杨丽涛；

【作者基本信息】 广西大学 ， 作物栽培学与耕作学， 2008， 硕士

【摘要】 为了挖掘广西的甘蔗生物固氮资源,分离筛选内生固氮菌株并探讨不同氮水平对甘蔗生物固氮的影响,本研究以Q124、Co281、B8等甘蔗品种为材料,从中分离得到21个具有乙炔还原活性的菌株。对部分菌株进行了生理生化测定、16S rRNA基因和nifH固氮基因克隆鉴定,同时研究了不同氮水平(0N、1/2 N)对甘蔗品种B8和ROC22体内固氮酶活性、植物活性物质多糖的影响。主要结果如下:1.通过对菌株进行生理生化特性、16S rRNA基因和nifH固氮基因克隆鉴定,研究表明:L2属于克雷伯氏菌属(Klebsiella),PCR扩增表明其16S rRNA基因全序列大小为1449 bp,nifH基因大小为724 bp;L3属于肠杆菌属(Enterobacteriaceae bacterium),PCR扩增表明其16S rRNA基因全序列大小为1448 bp,nif H基因大小为365 bp;L4属于克雷伯氏菌属(Klebsiella),PCR扩增表明其16S rRNA基因序列大小为904 bp。2.甘蔗品种B8的多糖含量在7、8、9月较高,ROC22的多糖含量在8、9月较高,可见都是在伸长盛期较高。经过回接固氮菌后脱毒与不脱毒B8品种基本上都表现出0 N水平处理的高于1/2 N水平处理的;ROC22不脱毒+接菌处理后表现的是0 N水平处理的低于1/2 N水平处理的。3.甘蔗在1/2 N处理下表现出更高的固氮活性。甘蔗分别经不脱毒、接菌处理和不脱毒、不接菌处理后,品种B8和ROC22都表现出0 N水平处理的固氮酶活性低于1/2 N水平处理的。4.热处理脱毒对甘蔗的固氮作用有显著的影响,固氮菌回接进脱毒处理蔗株体内,较不脱毒处理的更能够发挥它的固氮作用。5.品种ROC22本身可能具有较高的生物固氮能力。更多还原

【Abstract】 In order to investigate the biological nitrogen fixation （BNF） resources of sugarcane, to isolate and screen endophytic nitrogen fixing bacteria strains from sugarcane, and to study the effects of different nitrogen levels on BNF of sugarcane, sugarcane vatieties Q124, Co281 and B8 from Guangxi Sugarcane Research Institute were employed as the plant materials in the present study. Twenty one strains of endophytic bacteria with capacity of reducing acetylene （C₂H₂） were isolated from them. Several strains of endophytic bacteria were identified on the base of physiological characteristics, the 16S rRNA gene and the nif H gene cloning. Nitrogenase activity and polysaccharide（PS） in sugarcane treated with different levels of N were determined. The results showed as frollows:1. The bacterium strain L2 belonged to Klebsiella and the 16S rRNA gene sequence in full length was 1449 bp, the nif H gene sequence was 724 bp. The bacterium strain L3 belong to Enterobacteriaceae bacterium and the 16S rRNA gene sequence in full length was 1448 bp, the nif H gene sequence was 365 bp. The bacterium strain L4 belong to Klebsiella and the 16S rRNA gene sequence in length was 904 bp.2. The PS content in different treatments reached its highest level at the booming stage of sugarcane. It showed the highest PS content from July to September in B8, and from August to September in ROC22. The PS content in zero N level treatment was increased as compared to that in the 1/2 N treatment in B8. However, the PS content in zero N plants showed lower than that in the 1/2 N plants without virus-free treatment but with nitrogen fixing bacterium inoculation in ROC22.3. Sugarcane plants showed higher nitrogenase activity in the 1/2 N level than that in the zero N level. The plants without virus-free treatment and / or not nitrogen fixing bacterium inoculation showed lower nitrogenasa activity in the zero N level than that in the 1/2 N level in both the varieties of B8 and ROC22.4. There was considerable effect on the biological nitrogen fixation in the virus-free treatment via heating. The effect of nitrogenase activity was stronger in the virus-free treatment as compared to the control with nitrogen fixing bacteria inoculated and without virus-free treatment.5. There was high nitogenase activity in variety of ROC22.更多还原