Screening effective rhizobial strains associated with Medicago polymorpha by BOX molecular fingerprint

Abstract:

[Objective] Competitive nodulation ability of 12 rhizobial strains associated with Medicago polymorpha is tested by using BOX-PCR Molecular fingerprint; effective rhizobial strains were finally confirmed using the nodule occupancy rate combined with plant growth. [Methods] The nodule occupancy rate calculated by comparing BOX-PCR Molecular finger-prints of inoculated strains with those part of re-isolated strains. [Results] It showed that nod-ule occupancy of strain SWF67523 from Yingjiang district was of the highest occupation nodulation rate, reach 93.33%, showing strong ability of competitive nodulation, and it in-creased the dry-weight of their host-plants for 100% by plant test; while the other strain SWF67409 was of lower nodule occupancy rate, but with highly nodulation rate and increased the dry-weight of their host-plants for 106.5%. Furthermore, strain SWF67394 obviously in-creased the dry-weight of their host-plants and with high nodulation rate and lower nodule occupancy rate, these two strains may had effect on influencing activities of the native rhizobia and other microorganisms in soil. [Conclusion] We have introduced the competitive nodula-tion ability in screening effective rhizobial strains, and obtained a strain SWF67523 that with highly competitive nodulation ability and highly ability of plant growth promoting, and plant growth promoting strains of SWF67409 and SWF67394, this will provide precarious strains resources for producing rhizobial inoculants.

Key words:Medicago polymorpha, Rhizobia, BOX-PCR, Molecular fingerprint, Nodule occupancy