Infection thread development in model legumes

Gage, Daniel J.

doi:10.1002/9781119409144.ch72

Cited by 4 publications

(4 citation statements)

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“…Plant tissue endophytes may originate either from environmental infection (horizontal transmission), or be vertically transmitted via seed or vegetative propagation ( Johnston-Monje and Raizada, 2011 ; Yan et al, 2019 ). Legume nodule colonization by symbiotic bacteria is a consequence of a complex genetic mechanism which has been well described, while colonization mechanisms by NRB are still unclear, although it appears the plant plays an important role ( Wang et al, 2018 ; Gage, 2020 ). In comparing plant and soil origin influences on nodule colonization by NRB, plant genotypes possess more favorable traits related to nodule occupancy by microbial communities ( Muresu et al, 2008 ; Pandya et al, 2013 ; Zgadzaj et al, 2015 ; Regus et al, 2017 ; Westhoek et al, 2017 ; Sachs et al, 2018 ).…”

Section: Discussionmentioning

confidence: 99%

Bradyrhizobium as the Only Rhizobial Inhabitant of Mung Bean (Vigna radiata) Nodules in Tropical Soils: A Strategy Based on Microbiome for Improving Biological Nitrogen Fixation Using Bio-Products

et al. 2021

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The mung bean has a great potential under tropical conditions given its high content of grain protein. Additionally, its ability to benefit from biological nitrogen fixation (BNF) through association with native rhizobia inhabiting nodule microbiome provides most of the nitrogen independence on fertilizers. Soil microbial communities which are influenced by biogeographical factors and soil properties, represent a source of rhizobacteria capable of stimulating plant growth. The objective of this study is to support selection of beneficial bacteria that form positive interactions with mung bean plants cultivated in tropical soils, as part of a seed inoculation program for increasing grain yield based on the BNF and other mechanisms. Two mung bean genotypes (Camaleão and Esmeralda) were cultivated in 10 soil samples. Nodule microbiome was characterized by next-generation sequencing using Illumina MiSeq 16S rRNA. More than 99% of nodule sequences showed similarity with Bradyrhizobium genus, the only rhizobial present in nodules in our study. Higher bacterial diversity of soil samples collected in agribusiness areas (MW_MT-I, II or III) was associated with Esmeralda genotype, while an organic agroecosystem soil sample (SE_RJ-V) showed the highest bacterial diversity independent of genotype. Furthermore, OTUs close to Bradyrhizobium elkanii have dominated in all soil samples, except in the sample from the organic agroecosystem, where just B. japonicum was present. Bacterial community of mung bean nodules is mainly influenced by soil pH, K, Ca, and P. Besides a difference on nodule colonization by OTU sequences close to the Pseudomonas genus regarding the two genotypes was detected too. Although representing a small rate, around 0.1% of the total, Pseudomonas OTUs were only retrieved from nodules of Esmeralda genotype, suggesting a different trait regarding specificity between macro- and micro-symbionts. The microbiome analysis will guide the next steps in the development of an inoculant for mung bean aiming to promote plant growth and grain yield, composed either by an efficient Bradyrhizobium strain on its own or co-inoculated with a Pseudomonas strain. Considering the results achieved, the assessment of microbial ecology parameters is a potent coadjuvant capable to accelerate the inoculant development process and to improve the benefits to the crop by soil microorganisms.

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Section: Discussionmentioning

confidence: 99%

Bradyrhizobium as the Only Rhizobial Inhabitant of Mung Bean (Vigna radiata) Nodules in Tropical Soils: A Strategy Based on Microbiome for Improving Biological Nitrogen Fixation Using Bio-Products

et al. 2021

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“…IT formation involves reorganization of actin microfilaments and endoplasmic microtubules, ultimately leading to inward polar growth of the cell wall surrounded by a plasma membrane and containing a matrix with enclosed bacteria, in a process that resembles pollen tube growth ( Gage, 2004 ; Oldroyd et al., 2011 ). At 48 hpi, the IT reaches the base of the root hair ( Larrainzar et al., 2015 ), and in some cases, infection is halted and no concomitant nodule organogenesis occurs, marking another important check point to control the extent of the symbiosis ( Gage, 2004 , 2019 ). In infections that will go on to form nodules, the first cell division associated with nodule organogenesis begins at approximately 36 hpi in specific cells underlying the IT ( Figure 1 A).…”

Section: The Infection and Nodule Organogenesis Programsmentioning

confidence: 99%

Right time, right place: The dynamic role of hormones in rhizobial infection and nodulation of legumes

Velandia¹,

Reid²,

Foo³

2022

Plant Communications

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“…The infection process starts when rhizobia enter root systems through natural cracks between epidermal cells at the base of emerging lateral roots (termed “crack entry”), or, more commonly, when compatible rhizobia induce curling and deformation of growing root hairs around the bacterial cells that subsequently enter through an intracellular infection thread (IT, Figure 1A ; Rae et al, 2021 ). Crack entry infection is considered more primitive than ITs because the host does not experience sophisticated cellular differentiation of root hairs ( Sprent, 2008 ; Gage, 2019 ), although some species of plants (e.g., Lotus japonicus ) can alter their mode of infection depending on the site of infection ( Montiel et al, 2021 ). Only the emerging root hairs are infectable, with polar root hair growth required to achieve the necessary root hair deformation and cell wall invagination to form an IT ( Turgeon and Bauer, 1985 ; Esseling et al, 2003 ).…”

Section: Introductionmentioning

confidence: 99%

“…They are taken up into the plant cytosol and surrounded by a plant-derived membrane ( Figure 1B ). The rhizobial cells with their plant surrounding membrane are known as symbiosomes, which are temporary plant organelles where nitrogen fixation takes place ( Gage, 2019 ; Pérez-Giménez et al, 2021 ). In the symbiosomes, rhizobia adjust their metabolism in response to the stress conditions, differentiating into bacteroids, after which the nitrogenase complex is expressed, leading to active N 2 -fixation ( Poole et al, 2018 ; Ledermann et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Competition, Nodule Occupancy, and Persistence of Inoculant Strains: Key Factors in the Rhizobium-Legume Symbioses

et al. 2021

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Biological nitrogen fixation by Rhizobium-legume symbioses represents an environmentally friendly and inexpensive alternative to the use of chemical nitrogen fertilizers in legume crops. Rhizobial inoculants, applied frequently as biofertilizers, play an important role in sustainable agriculture. However, inoculants often fail to compete for nodule occupancy against native rhizobia with inferior nitrogen-fixing abilities, resulting in low yields. Strains with excellent performance under controlled conditions are typically selected as inoculants, but the rates of nodule occupancy compared to native strains are rarely investigated. Lack of persistence in the field after agricultural cycles, usually due to the transfer of symbiotic genes from the inoculant strain to naturalized populations, also limits the suitability of commercial inoculants. When rhizobial inoculants are based on native strains with a high nitrogen fixation ability, they often have superior performance in the field due to their genetic adaptations to the local environment. Therefore, knowledge from laboratory studies assessing competition and understanding how diverse strains of rhizobia behave, together with assays done under field conditions, may allow us to exploit the effectiveness of native populations selected as elite strains and to breed specific host cultivar-rhizobial strain combinations. Here, we review current knowledge at the molecular level on competition for nodulation and the advances in molecular tools for assessing competitiveness. We then describe ongoing approaches for inoculant development based on native strains and emphasize future perspectives and applications using a multidisciplinary approach to ensure optimal performance of both symbiotic partners.

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Infection thread development in model legumes

Cited by 4 publications

References 95 publications

Bradyrhizobium as the Only Rhizobial Inhabitant of Mung Bean (Vigna radiata) Nodules in Tropical Soils: A Strategy Based on Microbiome for Improving Biological Nitrogen Fixation Using Bio-Products

Bradyrhizobium as the Only Rhizobial Inhabitant of Mung Bean (Vigna radiata) Nodules in Tropical Soils: A Strategy Based on Microbiome for Improving Biological Nitrogen Fixation Using Bio-Products

Right time, right place: The dynamic role of hormones in rhizobial infection and nodulation of legumes

Competition, Nodule Occupancy, and Persistence of Inoculant Strains: Key Factors in the Rhizobium-Legume Symbioses

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