摘要
Lectins and leghemoglobins in legumes play the important roles, respectively, in recognition of host plants to their own rhizobia, and lowering the oxygen partial pressure surround the bacteroids and protecting nitrogenase from oxygen in symbiotic nitrogen_fixing nodules.In order to investigate the non_leguminous recognition of rhizobial bacteria relating to nitrogen fixation, plant expression vectors containing pea lectin gene ( pl ) and Parasponia hemoglobin gene ( phb ) have been, respectively, constructed in a plasmid and the plasmid has been introduced into tobacco ( Nicotiana tabacum L.) using Agrobacterium tumefaciens (Smith et Townsend) Conn as a vehicle for transformation. PCR and Southern blot demonstrated that the two genes were integrated into the genome of the tobacco plants. Histochemical staining for GUS activity, Western blotting,and in situ hybridization of pea lectin showed that they were expressed at translational level in the plants. These results may provide a clue for exploring whether Rhizobium leguminosarum bv. viciae could extend its host range and make the transgenic tobacco plants have the possibility of being symbiotic, or associative to nitrogen fixation.
豆科植物凝集素和血红蛋白分别在植物识别其相应的根瘤菌和在根瘤内降低氧分压保护固氮酶的共生固氮作用中起重要作用。将豌豆 (PisumsativaL .)凝集素基因 (pl)和Parasponiaandersonii血红蛋白基因 (phb)构建到同一植物表达载体上 ,通过根癌土壤杆菌 (Agrobacteriumtumefaciens (SmithetTownsend)Conn)介导法转化烟草 (Nico tianatabacumL .) ,经PCR扩增和Southernblot分析 ,证明外源双价目的基因已同时整合到转基因植株的基因组中。用GUS组织化学染色、Westernblot和凝集素原位杂交实验 ,证明gus报告基因和pl基因已在转基因烟草植株中得到转译表达。这一结果将为根瘤菌能否扩大宿主范围 ,使烟草与豌豆根瘤菌具有共生或联合固氮作用的可能性研究奠定基础。
基金
TheNationalNaturalScienceFoundationofChina ( 3 95 70 194) .
