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Title: CHARACTERISTICS OF RHIZOBIA ASSOCIATED WITH DALEA SPP. IN THREE PRAIRIE AREAS OF MINNESOTA.

Author
item Van Berkum, Peter
item TLUSTY, B - UNIVERSITY OF MINNESOTA
item GRAHMA, P - UNIVERSITY OF MINNESOTA

Submitted to: Canadian Journal of Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2004
Publication Date: 10/26/2005
Citation: Van Berkum, P.B., Tlusty, B., Grahma, P.H. 2004. Characteristics of rhizobia associated with dalea spp. in three prairie areas of minnesota.. Canadian Journal of Microbiology 51:15-23.

Interpretive Summary: Many legumes species form a beneficial relationship with soil bacteria generally known as rhizobia. The benefit is that rhizobia in this relationship provide the plant nitrogen extracted directly from the atmosphere and obviate the plant's need for soil nitrogen. The ecosystems of Midwestern prairies have fragmented, their recovery depends on the use of native legumes such as Dalea purpurea (purple prairie clover) but nothing at all is known about the rhizobia. This study was done to provide the Minnesota Department of Transportation (MDOT) specific information about the rhizobia of purple prairie clover for implementation in prairie restoration programs. From the results we concluded that the rhizobia of this legume are highly diverse and vary according to prairie of origin. Therefore, restoration efforts should consider the genetics of the rhizobia in addition to other factors. This information will be useful to scientists, ecologists and staff members of MDOT with interest in rhizobia and prairie ecosystem improvement.

Technical Abstract: Habitat fragmentation affects the biodiversity and function of above-ground organisms in natural ecosystems, but has not been studied for effects on belowground species. In this paper we consider the diversity of the rhizobia associated with the indigenous legume Dalea purpurea in three fragmented prairie areas in Minnesota. Using Dalea purpurea as a trap host 218 rhizobia were recovered from these soils, then were characterized using BoxA1R PCR. Three major and 13 minor groups were distinguished based upon a similarity of greater than 75% in fingerprint patterns. Each major group consisted almost exclusively of rhizobia from a single prairie, with the diversity of Dalea rhizobia recovered from the Hayden prairie less than obtained with rhizobia from the other prairies. Based on 16S rRNA gene sequence analysis, isolates from the Hayden, Ordway and Kellogg-Weaver Dunes prairies were most similar to R.etli and R.leguminosarum, R. gallicum, and Mesorhizobium amorphae and M. huakuii, respectively. This variation in the dominant microsymbiont species across the three prairies studied was unexpected, but could have been influenced by both the limited number of samples we were allowed to take from each area, and by unanticipated cross nodulation between native legumes in each prairie area.