Screening And Molecular Marking Of Highly Efficiency Symbiotic Rhizobia On Different Alfalfa Cultivars

In this research, highly effective strains were screened for four alfalfa cultivars (including cultivars WL323, Vector, zhongmu No.1 and RS) from ten meliloti rhizobia by vermiculite-pot and water-tubes tests. Furthermore, the genetic diversity among the tested rhizobia was determined by different molecular methods, including BOX-PCR, 16S rDNA, nod A, nifH PCR-RFLP and nod A sequencing.The results of symbiotic experiments showed that, after inoculated with different meliloti rhizobia, the plant shoot dry weight, plant height, and the total nodule number of the alfalfa cultivars increased than the no inoculated one. The effective strains of cultivar WL323 were NMG024-1, XJ96375 and XJ96411, compared with controls, of which the plant shoot dry weight increased 775.0%, 443.8% and 350.0%, respectively; strains NMG052-1, XJ96411 and NMG024-1 had good compatibility with Cultivar Vector, and the plant shoot dry weight increased 633.3% when inoculated NMG052-1; Cultivar Zhongmu No.1 had good symbiotic efficiency with the strains NMG024-1, NMG024-2 and NMG002-2, of which, strain NMG024-1 was the best one, and the plant shoot dry weight increased 618.2% than the control when inoculated with NMG024-1. While, cultivar RS had good compatibility with XJ96375, NMG024-2, XJ96411 and NMG024-1.Analysis of BOX-PCR showed that the genetic diversity was existed among the 10 rhozbia, and 4 genetic groups were formed at the level of 70% similarity. However, the results of 16S rDNA, nod A, nifH PCR-RFLP and nod A sequencing showed that there had no difference among these strains.Combining symbiotic experiments and BOX-PCR analysis, the results showed that BOX-PCR analysis revealed the correlation between cultivars and rhizobia in somehow. For example, XJ96379 nd NMG001-3 had good symbiotic effect with RS, and they clustered in group I; Strains in group II hhad good compatibility with cultivar WL323; Cluster IV included NMG052-1, NMG024-1 and NMG024-2, among them, NMG052-1 and NMG024-1 had good symbiotic effect with Vector; at the same time, strains NMG024-2 and NMG024-1 were effective with cultivar Zhongmu No.1; furthermore, NMG024-1 was highly efficiency with RS and WL323, Which showed that strains in group IV had broad host range.