Never too many? How legumes control nodule numbers

Mortier, Virginie; Holsters, Marcelle; Goormachtig, Sofie

doi:10.1111/j.1365-3040.2011.02406.x

Cited by 124 publications

(91 citation statements)

References 179 publications

(455 reference statements)

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“…Symbiotically produced IAA alone or along with other plant hormones involved in several stages of establishment of symbiotic relationship and also transported to the plant for its use. Rhizobial induced local accumulation of auxins stimulates the formation of nodule primordia [32] and also necessary for growth and maintenance of root nodules. Ghosh et al [33] suggested that IAA content produced by the bacterioids in the nodule and supplied to the host plant is the second line of symbiosis apart from nitrogen fixation.…”

Section: Plant Growth Promoting Charactersmentioning

confidence: 99%

Phenotypic, Stress Tolerance and Plant Growth Promoting Characteristics of Rhizobial Isolates from Selected Wild Legumes of Semiarid Region, Tirupati, India

Bhargava¹,

Murthy²,

Kumar³

et al. 2016

AiM

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Rhizobia are vital for nitrogen input, fertility of soil and legume plant growth. Knowledge on rhizobial diversity from arid and semiarid areas is important for dry land agriculture in the context of climatic change and for economic utilization. This study provides morphological, biochemical, stress tolerance and plant growth promoting characteristics of fifteen rhizobial isolates from the nodules of same number of wild legumes and one isolate from cultivated Arachis hypogea from semi-arid region, Tirupati. The bacterial isolates were confirmed as rhizobia based on colony morphology and biochemical tests. Based on the colour change of YMA-BTB medium, eight isolates were identified as slow growers and six were fast growers. The isolates differed in growth pattern, colony morphology, antibiotic resistance at higher concentrations and uniformity in utilization of carbon and nitrogen sources. The isolates are tolerant to NaCl up to one percent, displayed normal growth at temperatures 28˚C -30˚C, at neutral pH and poor growth at pH 5and 9. The isolates varied in the production of EPS and IAA, positive for phosphate solubilization and siderophore formation. This functional diversity displayed by the isolates can be utilised for the legume crop production by cross inoculation.

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Section: Plant Growth Promoting Charactersmentioning

confidence: 99%

Phenotypic, Stress Tolerance and Plant Growth Promoting Characteristics of Rhizobial Isolates from Selected Wild Legumes of Semiarid Region, Tirupati, India

Bhargava¹,

Murthy²,

Kumar³

et al. 2016

AiM

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“…First, an internal regulation leads to an "auto-regulation of nodule number" (AON) by the host plant, through a systemic feedback repression of nodulation by pre-existing nodules (Reid et al 2011;Mortier et al 2012 for reviews). Deregulated mutants with a hypernodulating phenotype were isolated in several legume species (Novak 2010;Reid et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Pea nodule gradients explain N nutrition and limited symbiotic fixation in hypernodulating mutants

Voisin

Prudent

Duc

et al. 2015

Agron. Sustain. Dev.

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Legumes fix atmospheric nitrogen by symbiosis with soil bacteria in root nodules. Legume yields are limited by the low capacity of N 2 fixation. Hypernodulating mutants have been selected decades ago to try to increase nodule number. However, literature data show that N fixation of hypernodulating mutants was not increased compared to parental lines. Here, we study the functional basis of limited N fixation associated to hypernodulation. We grew two wild type genotypes and nine hypernodulating mutants of pea in hydroponics in three greenhouse experiments. We measured the following traits related to N nutrition during the vegetative period: nodule number, plant N uptake, nodule-specific activity, and plant and nodule concentrations. Genetic and environmental variations induced nodule gradients. These gradients were used to set quantitative relationships between N nutrition traits and nodule number. We compared the relationships obtained for hypernodulating and for wild types. N nutrition traits were analysed together with C nutrition traits, through correlation networks. Our results show that higher nodule number of hypernodulating mutants is correlated with lower levels of nodule activity, from −25 to −60 %, by comparison to the wild type. Higher nodule number of hypernodulating mutants is also correlated with lower total N uptake by symbiotic fixation, from −0 to −60 %, by comparison to the wild type. Findings demonstrate that N nutrition is not a factor limiting growth in hypernodulating mutants, as shown by N nutrition index higher than 1, indicating N nutrition in excess. The correlations suggest that limited N 2 fixation in hypernodulating mutants arises from restricted shoot growth, which limits the plant capacity to accumulate N. Furthermore, symbiotic efficiency decreased with increasing nodule number, down to a minimal value for hypernodulating mutants. Thus, to overcome the trade-off between N benefits from N 2 fixation and carbon nodulation costs, the hypernodulation trait should be associated with high shoot growth capacity in breeding programs.

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“…Most previous experiments on ozone effects on clover were conducted in 61 brassinosteroids and jasmonic acid (JA) suggested as likely candidates for the SDI 85 signal (Mortier et al 2012). Nodulation is also determined by local hormonal 86 regulation, with JA, abscisic acid (ABA) and ethylene together acting as local negative 87 regulators of nodule initiation (Mortier et al 2012). 88…”

Section: Introduction 29mentioning

confidence: 99%

Highlighting the threat from current and near-future ozone pollution to clover in pasture

Hewitt¹,

Mills²,

Hayes³

et al. 2014

Environmental Pollution

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Never too many? How legumes control nodule numbers

Cited by 124 publications

References 179 publications

Phenotypic, Stress Tolerance and Plant Growth Promoting Characteristics of Rhizobial Isolates from Selected Wild Legumes of Semiarid Region, Tirupati, India

Phenotypic, Stress Tolerance and Plant Growth Promoting Characteristics of Rhizobial Isolates from Selected Wild Legumes of Semiarid Region, Tirupati, India

Pea nodule gradients explain N nutrition and limited symbiotic fixation in hypernodulating mutants

Highlighting the threat from current and near-future ozone pollution to clover in pasture

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