论文部分内容阅读
利用内生固氮菌在植物体内固氮有可能开辟一条非豆科作物直接利用生物固氮的捷径。Klebsiella oxytoca SA_2是一株从生长在流沙地的先锋植物——沙竹(Psam-mochloa mongolica)内分离到的固氮菌。水稻幼苗接种SA_2限菌培养,免疫金银染色根和茎的石蜡切片确证了SA_2的内生特性。SA_2可以从水稻侧根发生时产生的裂隙和根表皮细胞胞间入侵,通过皮层细胞间隙向内和纵向迁移。SA_2可以进入根中柱,在导管内定殖。定殖在水稻根基皮层细胞间隙、木质部导管和茎基导管内的SA_2表达了固氮酶,表明植物体内有适合内生固氮菌固氮的微环境。研究还发现水稻和玉米根的内皮层细胞在SA_2侵入后解体,可能表现为严格的局部超敏反应。
Nitrogen fixation by endophytic azotobacteria in plants may open up a shortcut to direct use of biological nitrogen fixation in non-leguminous crops. Klebsiella oxytoca SA_2 is a nitrogen-fixing bacteria isolated from Psam-mochloa mongolica growing in quicksand. SA2 limited bacteria culture of rice seedlings inoculation, immunohistochemical staining of root and stem paraffin sections confirm the endogenous properties of SA_2. SA_2 can intervene from the fissures and root epidermal cells that occur when the lateral roots of rice occur and migrate inwardly and longitudinally through the cortical cell interspaces. SA_2 can enter the root column, colonization in the catheter. Nitrogenase was expressed in SA_2 colonized in the intercellular space of root cortex, xylem and stem-root ducts in rice plants, indicating that the plants had microenvironment suitable for nitrogen fixation of endogenous nitrogen-fixing bacteria. The study also found that the endodermal cells of rice and maize roots disintegrated after SA_2 invaded, which may appear to be severe local hypersensitivity.