Selecting improved Lotus nodulating rhizobia to expedite the development of new forage species

Abstract

Aims In the past decades the increasing focus by Australian pasture development programs on the genus Lotus has seen the evaluation of many species previously untested in Australia. In field trials, nodulation failure was commonplace. This work was undertaken to select effective symbionts for Lotus to ensure further agronomic evaluation of the genus was not compromised. The symbiotic needs of Lotus ornithopodioides were a particular focus of the studies.Methods Glasshouse experiments were undertaken to evaluate symbiotic relationships between 15 Lotus spp and 23 strains of nodulating Mesorhizobium loti. This was followed by evaluation of elite rhizobial strains for their ability to persist and form nodules under field conditions. Results Complex symbiotic interactions were recorded between strains of lotus rhizobia and the different species of Lotus. Notably, the rhizobia that are currently provided commercially in Australia for the inoculation of Lotus corniculatus (strain SU343) and Lotus uliginosus (strain CC829) did not form effective symbioses with the promising species L. ornithopodioides and L. maroccanus. No strain we evaluated was compatible with all the Lotus species, however several strains with a broad host range were identified. WSM1293 and WSM1348 were the most effective strains on L. ornithopodioides and L. peregrinus.These strains were also moderately effective on L. corniculatus (79 and 52% of SU343), less effective on L. maroccanus (26 and 49% of SRDI110) but were ineffective on L. uliginosus. The latter species overall had very specific rhizobial needs. Both WSM1293 and WSM1348 produced adequate levels of nodulation when inoculated on L. ornithopodioides, over two seasons at three field sites. Conclusions Effective and persistent strains are now available that should allow the un-compromised evaluation of many of the contemporary Lotus species in the field. Selecting a strain for use in commercial inoculants will be more problematic, given the very Plant Soil (2011) 348:231-243

The Rhizobia-Lotus Symbioses: Deeply Specific and Widely Diverse

“…Also mesorhizobia strains isolated from L. oroboides in Mexico failed to nodulate L. corniculatus although unfortunately no other Lotus were tested ( Qian and Parker, 2002 ). Neither of the Australian commercial inoculant strains for L. uliginosus (CC829) and L. corniculatus (SU343) can fix nitrogen with the promising forage species L. ornithopodioides ( Howieson et al, 2011 ). Indeed, these authors found no strains compatible with all the 15 Lotus species evaluated.…”

“…In some cases, the uncertainty about the bacterial origin can lead to uncertainty about its symbiotic properties. For instance, it is unclear if SU343 (equivalent names NZP 2196, ICMP 3663, ICMP 10808, PDDCC 3663, ATCC 35173, DSM 6046) was originally isolated from L. corniculatus in United States (as described for ICMP10808 and mentioned in Howieson et al, 2011 ), or from Lupinus sp. in Australia (as for ICMP 3663/NZP2196 and ATCC 35173, and in Charlton et al, 1981 ).…”

“…The use of relatively few strains, which often were isolated long ago and brought from distant places, accentuate the need of studies toward selection of efficient rhizobial strains which perform optimally with local cultivars and prevailing environmental conditions. In an interesting study aimed to identify efficient strains for more contemporary forage species such as L. ornithopodiodes , Howieson et al (2011) observed the difficulties to find strains that could optimally perform with all Lotus spp. of agronomic interest in New Zealand, because of the large host-strain interaction for symbiotic nitrogen fixation.…”

Lucerne and other perennial legumes provide new options for rain fed livestock production in the Mediterranean-climate region of Chile

“…The strains used for the inoculation of M. sativa, Lotus spp. and H. coronarium were selected as effective strains for these species, with some strains used as commercial inoculants in Australia (Langer et al, 2008;de Koning et al, 2010;Howieson et al, 2011). In this study, strain WSM2141 was found in most of the nodules from M. sativa two months after sowing and in 32% of the nodules a year later; however, in L. corniculatus, L. tenuis and H. coronarium, the inoculant strains were completely displaced by soil rhizobia.…”

INOCULACIÓN DE VAINITA (Phaseolus vulgaris L.) CON DIFERENTES CONCENTRACIONES DE Rhizobium etli Y SU INFLUENCIA SOBRE EL RENDIMIENTO DEL CULTIVO

“…Las plantas leguminosas tienen altos requerimientos en fósforo y potasio, caso contrario ocurre con el N mineral, ya que son capaces de fijar suficientes cantidades a través de la fijación biológica de N (Howieson et al, 2011). Estas plantas son sensibles a las deficiencias de fósforo, potasio y azufre, nutrientes que afectan de manera directa la fijación biológica de nitrógeno, e indirectamente el crecimiento de la leguminosa (Divito & Sadras, 2014).…”