Logo image
Back
Root and root hair mechanisms that confer symbiotic competence for nodulation in acidic soils within Medicago species: a holistic model
Journal article   Peer reviewed

Root and root hair mechanisms that confer symbiotic competence for nodulation in acidic soils within Medicago species: a holistic model

Y. Cheng, E.L.J. Waktin, J.G. Howieson and G.W. O'Hara
Australian Journal of Experimental Agriculture, Vol.45(3), pp.231-240
2005
DOI: https://doi.org/10.1071/EA03150
url
Link to Published Version *Subscription may be requiredView

Abstract

Three experiments were undertaken to investigate the mechanisms used by the annual medic species, Medicago murex (Murex medic) to achieve nodulation more rapidly in acidic soils than the perennial species Medicago sativa (lucerne). In experiment 1, numbers and locations of root hairs on the primary roots of medic and lucerne were determined from plants grown in soil of pH 4.3 and 7.0. Experiment 2 enumerated the numbers of Sinorhizobium medicae (rhizobia) associated with the roots of medic and lucerne when grown in an acidic soil. Experiment 3 used a GFP-marked strain of rhizobia to determine the localised distribution of rhizobia along various zones of the primary roots of medic and lucerne in soil of pH 4.3 and 7.0. When grown in an acidic soil, medic produced 60% more root hairs/mm root along the primary root axis compared with lucerne, from 7 days after sowing. In soil of low pH, medic also had higher numbers of rhizobia associated with its entire root system than lucerne, with about 103 cfu/cm root throughout the 24-day period of the experiment, compared with lucerne for which rhizobial numbers decreased from 102 to 11 cfu/cm root over the same time period. When the intensity of fluorescence emitted by a GFP-marked transconjugant of rhizobia was measured at localised zones along the primary root of medic and lucerne grown in the acidic soil, it was 1.8-fold higher from the roots of medic than lucerne at 7 days after sowing, indicating higher numbers of rhizobia along medic roots. Hence, the numbers of rhizobia associated with the entire root system, and those colonised on localised zones of the primary root of medic were both higher than that of lucerne. These fundamental differences between the 2 species, combined with the earlier finding that lucerne tends to acidify its rhizosphere more than medic, allowed us to construct conceptual models that attempt to explain the increased symbiotic competency of medic compared with lucerne, and the different nodulation responses between medic and lucerne at low pH.

Details

UN Sustainable Development Goals (SDGs)

This output has contributed to the advancement of the following goals:

#2 Zero Hunger

Source: InCites

Metrics

37 Record Views
7 Times Cited - Web of Science

InCites Highlights

These are selected metrics from InCites Benchmarking & Analytics tool, related to this output

Collaboration types
Domestic collaboration
Citation topics
3 Agriculture, Environment & Ecology
3.97 Plant Pathology
3.97.892 Rhizobium-Legume Symbiosis
Web Of Science research areas
Agriculture, Multidisciplinary
ESI research areas
Agricultural Sciences
Logo image