The symbiotic requirements of different Medicago spp. suggest the evolution of Sinorhizobium meliloti and S-Medicae with hosts differentially adapted to soil pH
The symbiotic requirements of different Medicago spp. suggest the evolution of Sinorhizobium meliloti and S-Medicae with hosts differentially adapted to soil pH
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DOI：
10.1007/s11104-005-0374-0
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发表时间：
2005-10-01
期刊：
影响因子：
4.9
通讯作者：
Howieson, JG
中科院分区：
文献类型：
--
作者：
Garau, G;Reeve, WG;Howieson, JG
苜蓿根瘤菌固氮作用的研究。属（Sinorhizobium medicae）和S.苜蓿草。为了研究两种微共生体对不同苜蓿属物种的共生要求，从地中海盆地自然栖息地生长的11种苜蓿属物种的根瘤中分离出39株细菌，再加上6种历史上的澳大利亚商业接种物，与苜蓿属宿主共生。根据与M.多形。然后设计16SrDNA特异性PCR引物，用于区分S. medicae和S.苜蓿草。PCR扩增结果证实了在温室中获得的物种分配。ERIC，BOXA1R和nif定向RPO1引物产生的PCR指纹图谱显示，地中海菌株的遗传异质性。ERIC和BOX引物的PCR指纹图谱显示，这些重复序列在S. meliloti和S. mediae，根据它们的种类将菌株聚类为两个不同的组。将中华根瘤菌物种与起源植物物种联系起来，我们发现中华根瘤菌。medicae主要与适应中等酸性土壤的medics如M. polymorpha，M. arabica和M. murex而S.草木樨主要分离自天然生长在碱性或中性pH土壤上的植物，如M. littoralis和M. tornata。此外，在温室实验中，S. medicae菌株能在M. murex和S.苜蓿草木虱对该种无侵染性。这一特征为S提供了一个非常显著的特征。医学从共生、基因型和文化特征的结果表明，S。meliloti和S.根据苜蓿在其自然生境中所占据的生态位，苜蓿对不同的苜蓿属物种具有不同的适应性。
Nitrogen fixing rhizobia associated with the Medicago L. genus belong to two closely related species Sinorhizobium medicae and S. meliloti. To investigate the symbiotic requirements of different Medicago species for the two microsymbionts, 39 bacterial isolates from nodules of eleven Medicago species growing in their natural habitats in the Mediterranean basin plus six historical Australian commercial inocula were symbiotically characterized with Medicago hosts. The bacterial species allocation was first assigned on the basis of symbiotic proficiency with M. polymorpha. PCR primers specific for 16S rDNA were then designed to distinguish S. medicae and S. meliloti. PCR amplification results confirmed the species allocation acquired in the glasshouse. PCR fingerprints generated from ERIC, BOXA1R and nif-directed RPO1 primers revealed that the Mediterranean strains were genetically heterogenous. Moreover PCR fingerprints with ERIC and BOX primers showed that these repetitive DNA elements were specifically distributed and conserved in S. meliloti and S. medicae, clustering the strains into two divergent groups according to their species. Linking the Sinorhizobium species with the plant species of origin we have found that S. medicae was mostly associated with medics well adapted to moderately acid soils such as M. polymorpha, M. arabica and M. murex whereas S. meliloti was predominantly isolated from plants naturally growing on alkaline or neutral pH soils such as M. littoralis and M. tornata. Moreover in glasshouse experiments the S. medicae strains were able to induce well-developed nodules on M. murex whilst S. meliloti was not infective on this species. This feature provides a very distinguishing characteristic for S. medicae. Results from the symbiotic, genotypic and cultural characterization suggest that S. meliloti and S. medicae have adapted to different Medicago species according to the niches these medics usually occupy in their natural habitats.