Nodulation studies on legumes exotic to Australia: symbiotic relationships between Chamaecytisus palmensis (tagasaste) and Lotus spp

Abstract

Strains of rhizobia were isolated from soil around the roots of tagasaste (Chamaecytisus palmensis) growing at 15 widely separated locations in south-eastem Australia. A further collection of strains of both Rhizobium loti and Bradyrhizobium sp. (Lotus) was assembled from 18 legumes including Lotus and other species symbiotically related to Lotus. The strains were used to inoculate tagasaste and 4 species of Lotus in experiments conducted under bacteriologically controlled conditions in a temperature-controlled glasshouse. Tagasaste formed nodules and fixed N2 with all of its homologous rhizobia but there was a wide range of effectiveness among the 15 strains. Tagasaste also formed nodules with each of the 18 strains from other species but fixed N2 with only 10. Four species of Lotus were inoculated with 3 tagasaste strains. One strain nodulated each species and fixed N2 with L. conimhricensis and L. corniculatus but not with L. parviflorus or L. pedunculatus. A second tagasaste strain formed nodules with all 4 Lotus spp. but did not fix N2, while the third nodulated only L. pedunculatus but did not fix N2. A pattern analysis based on the nodulating ability of the host plants in association with 21 strains showed that tagasaste and L. corniculatus formed 1 symbiotic group, and the other 3 Lotus species formed a third group. The pattern analysis procedure based on nodulating capacity of 21 rhizobial strains in association with the 5 host species indicated substantial symbiotic diversity within the collection, with the strains comprising 8 different symbiotic groups. No strain was highly effective on both tagasaste and any of the 4 species of Lotus. Data were insufficient to classify the root-nodule bacteria of tagasaste as either Rhizobium loti or Bradyrhizobium sp. (Lotus).

A novel symbiotic nitrogen-fixing member of the Ochrobactrum clade isolated from root nodules of Acacia mangiu

“…IC, infected cell; UIC, uninfected cell; BD, bacteroid; PBM, peribacteroid membrane; CW, cell wall; N, nucleus. minous plant growing in tropical and sub-tropical areas are very diverse; namely, both genera Rhizobium and Bradyrhizobium can nodulate the same host plant (Fuentes et al, 2002;Gault et al, 1994;Haukka et al, 1998;Keyser et al, 1982). The strains isolated from Acacia trees in this work were classified into three different genera, Rhizobium and Bradyrhizobium belonging to the family Rhizobiaceae, and Ochrobactrum, a member of Brucellaceae.…”

Morphological Changes of Rhizobia in Peat Cultures

“…strain SU343 on inoculated beads according to the method of Somasegaran and Hoben (19), using Lotus corniculatus cv. Granger grown as described by Gault et al (4). The number of nodulated plants was recorded after 6 weeks, and the MPN was calculated using the MPNES computer program (23).…”

Novel infection process in the indeterminate root nodule symbiosis between Chamaecytisus proliferus (tagasaste) and Bradyrhizobium sp.

“…It was introduced in the last century in other parts of the world, especially in Australia and New Zealand (Snook, 1996) where it was misnamed tree‐lucerne (European name for alfalfa) alluding to its comparative forage value with alfalfa. In Australia, tagasaste has been reported to be nodulated by strains of rhizobia and bradyrhizobia (Gault et al. , 1994), but in the Canaries only the slow‐growing bradyrhizobia isolated from endemic woody legumes have been found to nodulate tagasaste effectively (León‐Barrios et al.…”