新疆豆科短命植物弯果胡卢巴根瘤与根瘤菌的特性

目的]对弯果胡卢巴根瘤增殖特性、根瘤显微结构、根瘤菌遗传聚类以及根瘤菌各种抗性进行观察、分析和鉴定.方法]分别利用不同基质培养、石蜡切片和树脂半超薄切片以及16S rRNA基因序列扩增和序列分析等技术方法对弯果胡卢巴根瘤和根瘤菌进行研究.结果]①在混合土(养花土:白杨林下土:沙土=1:1:1)中有明显结瘤且植株结荚最多,多数根瘤呈掌状和姜形;②显微结构显示根瘤由表及里分为表层、皮层、维管束、已侵染细胞与未侵染细胞几部分;③对根瘤菌16S rRNA基因全长序列(1377bp)测序并分析,结果显示其与苜蓿中华根瘤菌16S rRNA基因的同源性达99.9%;④根瘤菌抗逆性鉴定结果显示,在温度为4℃～60℃(20 Min)、pH值为6.0～12.0、NaCl浓度为0%～2%的范围内根瘤菌均可正常生长;低浓度的卡那霉素、链霉素及头孢霉素等抗生素(25μg/mL,)就能完全抑制根瘤菌的生长,但仍能在100μg/mL的氨苄青霉素中正常生长.结论]弯果胡卢巴结瘤需要较好的土壤及通气条件;根瘤簇生,瘤内含大量被根瘤菌侵染的细胞;弯果胡卢巴根瘤菌与苜蓿中华根瘤菌(sinorhizobium meliloti,)同源性最高,是一类较耐高温和强碱的菌株.

Characterization of root nodule and rhizobium of a leguminosae ephemeral plant- Trigonella arcuata C.A.Mey in Xinjiang

OBJECTIVE: We studied root nodule proliferation, nodule microstructure, genetic cluster and stress resistance of the rhizobium of Trigonella arcuata. METHODS: We characterized root nodule and rhizobium with various soil matrixes cultivation, paraffin section, resin semi-ultrathin section techniques, and 16S rRNA gene cluster analysis. RESULTS: (1) Plants grew in mixed soil (nutritious garden soil: poplar zone soil: desert sands = l:1:1), had the most nodule proliferation and bore the most pods. The shapes of nodule were palm- or ginger-like; (2) Microstructure of the nodule revealed five different parts differentiated within the nodule: epidermis (E), cortex (C), vascular bundle (VB), infected cells (IC) and uninfected cells (UIC); (3) Genetic cluster analysis of the full length 16S rRNA gene sequence (1377 bp) indicated that the rhizobium isolated shared the highest identities with Sinorhizobium meliloti; (4) The rhizobium could grow between 4 and 60 degrees C (20 min), pH 6.0-12.0 and 0-2% NaCl. For the antibiotic sensitivity, the rhizobium could not grow normally in medium with 25 microg/mL Kanamycin, Streptomycin or Cephalothin, except for 100 microg/mL Ampicillin. CONCLUSION: Good conditions of soil matrixes were important for nodulation of T. arcuata; A large quantity of cells in fascicular nodules were infected by rhizobia; 16S rRNA gene sequence of T. arcuata shared the highest identities with that of Sinorhizobium meliloti, and this strain was able to tolerate relatively higher temperature and alkalin.