The field distribution of strains of nodule bacteria from species of Medicago

Abstract

Tests of nodulation and ability to fix nitrogen, together with serological reactions, are reported for localized isolates from Medicago hispida var. denticulata and M. laciniata. For a particular host species strains were distributed randomly within the area investigated, except that a particular somatic antigen found among M. laciniata isolates was limited to one locality. In reciprocal tests between isolates from these two hosts, nodulation has been mainly confined to the homologous host. Although some strains fail in laboratory tests to nodulate the homologous host and although separation into two groups is not complete, there are relatively few cases of discrepancy and many of these show intermediate characteristics. Medicago sativa and Melilotus alba are generally readily nodulated by isolates from both field hosts. The nodulation differences between strains from the two field hosts are paralleled to some extent by serological properties, but it is suggested that this correlation shows recent common origin of similar strains rather than any fundamental relationship between invasibility and antigenic constitution. Effective association was seldom, if at all, achieved with M. laciniata, whereas with other testing hosts effective responses were in the majority and even included a number of isolates originating from M. laciniata and ineffective with that species as host.

The Influence of the Legume in Root‐nodule Symbiosis

“…As in the Trifolium group a great variety of patterns of effectiveness have been found, and it is not possible from the available data to point to any significant relationships. Medicago laciniata seems to differ from other species of this genus in failing to give a completely effective symbiosis with any strain of bacteria (Purchase et al 1951)~ and in this respect resembles Trifolium ambiguum. Recent work by Hely (unpublished data) has shown that effective strains with Medicago laciniata are found in certain areas in its Australian range which resembles the normal habitat of this species.…”

“…The Medicago, Melilotus, Trigonella group provides further examples of host specificity in symbiotic effectiveness as between: (I) genera (Burton & Erdman, 1940;Strong, 1940;Purchase et al 1951); ( 2 ) species of Medicago (Bond, Wilson & Wagner, 1936;Burton & Wilson, 1939;Purchase et al 1951); (3) species of Melilotus (Wilson, Burton & Bond, 1937) and (4) varieties of lucerne (Jordan & Garrard, 1951;Erdman & Means, 1953). As in the Trifolium group a great variety of patterns of effectiveness have been found, and it is not possible from the available data to point to any significant relationships.…”

Complementary Methods for the Differentiation of Rhizobium meliloti Isolates

“…Observations documented in the older literature emphasize that serological characteristics of Rhizobium strains are stable, in contrast with other phenotypic characteristics, such as symbiotic effectiveness (19,20,31,32). In recent years, however, workers have attempted to develop alternative methods of strain identification which are inexpensive…”

“…This can be attributed in part to the success achieved in developing serological methods of identification for these latter two species. There are few reports on the successful use of serological methods for identifying and differentiating R. meliloti isolates, most of them being found in the older literature (4,8,19,20,28,30). Stevens (28) used the tube agglutination serological method to show that a random collection of R. meliloti isolates could be placed into two serological groups.…”

Characterization of Bradyrhizobium japonicum serocluster 123 member isolates native to Iowa soils

“…Heterogeneity of R^ meliloti was first suggested by Hughes and Vincent (1942) and later by Purchase et al (1951) by using serology. Since then, serological techniques have been used extensively to differentiate heterogeneity within a particular rhizobial strain.…”