凉山州新银合欢根瘤菌的共生有效性及遗传多样性

Symbiotic efficiency and genetic diversity of the rhizobia isolated from Leucaena leucocephala in Liangshan Prefecture

摘要:

摘要: 【目的】研究分离自四川凉山州新银合欢根瘤菌的遗传多样性和共生有效性。【方法】采用16S rRNAＲFLP、BOX-PCR、AFLP、多位点持家基因序列的联合分析及无氮水培法对33 株供试新银合欢根瘤菌的遗传多样性和共生有效性进行研究。【结果】分析表明，3种方法在属水平的分群结果具有较好的一致性，有1个Mesorhizobium属的菌株、3 个Bradyrhizobium属的菌株、3个Ｒhizobium属的菌株，26个相似度较高的菌株属Sinorhizobium。16S rRNA-recA-atpD-glnII序列联合构建的新银合欢根瘤菌系统发育树表明，SCAU203、SCAU211可能分别是Rhizobium和Bradyrhizobium的新类群，另外3个代表菌株分别位于Sinorhizobium、Mesorhizobium、Bradyrhizobium分支，分别与S.americanum、M.Plurifarium、Ｒ.huautlense亲缘关系最近。无氮水培接种试验筛选出2个共生固氮效果好、与不接种对照处理差异达显著水平的菌株SCAU229和SCAU307，有3个菌株不仅不具共生有效性，甚至不利于宿主的生长，其余84%的供试菌为低效或无效菌株。【结论】凉山州新银合欢根瘤菌具有丰富的遗传多样性，分布于4 个属: Rhizobium、Bradyrhizobium、Mesorhizobium、Bradyrhizobium，79%为Sinorhizobium属的菌株，优势菌群为Sinorhizobium。该区的新银合欢根瘤菌大多数的共生有效性差。

Abstract:

Abstract: ［Objective］ We analyzed the symbiotic efficiency and genetic diversity of rhizobia isolated from Leucaena leucocephala in Liangshan Prefecture of SichuanProvince．［Methods］We studied genetic diversity of these isolates with 16S rRNA ＲFLP，BOX-PCＲ and AFLP fingerprinting，and constructed phylogenetic tree based on the concatenated sequences of the four housekeeping genes 16S rRNA，recA，atpD and glnII．The nodulation ability and the symbiotic efficiency of the isolates were tested by plant inoculation assay on their original host plant．［Results］ Genetic diversity and phylogenetic tree indicate that 26 isolates were assigned as Sinorhizobium，3 Bradyrhizobium，3 Rhizobium and 1 Mesorhizobium．SCAU203 might represent a new Ｒhizobium group，SCAU211 might represent a new Bradyrhizobium group，the other three representative strains were located in three phylogenic branches and closely related to S.americanum，M．plurifarium and R.huautlense，respectively．In the nodulation and symbiotic efficiency assay，only 2 of the 20 isolates promoted the growth of L．leucocephala，but 3 isolates had a growth slowing effect on the host，while the other isolates (84%) were ineffective on symbiotic nitrogen fixation．［Conclusion］The majority of rhizobia isolated from L.leucocephala in Liangshan Prefecture were ineffective on symbiotic nitrogen fixation.