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

Velandia, Karen; Reid, James B.; Foo, Eloise

doi:10.1016/j.xplc.2022.100327

Cited by 27 publications

(20 citation statements)

References 134 publications

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“…This phenotype might arise from the increased number of ITs in roots infected by a nifA mutant compared to the wild type (Figure 4B and Supplementary Figure 3). In line with the current hypothesis that auxin positively regulates epidermal infections (Velandia et al, 2022), auxins overexpression in the P. phymatum nifA mutant seems to act locally and promote the occurrence of infection events. This is reminiscent of the L. japonicum-M. loti symbiosis, where auxin was proposed to be a promotor of the initiation or elongation of the IT formation.…”

Section: Discussionsupporting

confidence: 83%

“…Phytohormones, especially auxin and cytokinin are also involved in coordinating the nodulation process ( Ferguson et al, 2010 ; Oldroyd et al, 2011 ; Liu et al, 2018 ; Velandia et al, 2022 ). Auxins were first discovered as plant hormones playing crucial roles in plant growth, development, embryogenesis and tropism ( Zhao, 2010 ).…”

Section: Introductionmentioning

confidence: 99%

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A novel function of the key nitrogen-fixation activator NifA in beta-rhizobia: Repression of bacterial auxin synthesis during symbiosis

Bellés-Sancho

Liu²,

Heiniger³

et al. 2022

Front. Plant Sci.

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Rhizobia fix nitrogen within root nodules of host plants where nitrogenase expression is strictly controlled by its key regulator NifA. We recently discovered that in nodules infected by the beta-rhizobial strain Paraburkholderia phymatum STM815, NifA controls expression of two bacterial auxin synthesis genes. Both the iaaM and iaaH transcripts, as well as the metabolites indole-acetamide (IAM) and indole-3-acetic acid (IAA) showed increased abundance in nodules occupied by a nifA mutant compared to wild-type nodules. Here, we document the structural changes that a P. phymatum nifA mutant induces in common bean (Phaseolus vulgaris) nodules, eventually leading to hypernodulation. To investigate the role of the P. phymatum iaaMH genes during symbiosis, we monitored their expression in presence and absence of NifA over different stages of the symbiosis. The iaaMH genes were found to be under negative control of NifA in all symbiotic stages. While a P. phymatum iaaMH mutant produced the same number of nodules and nitrogenase activity as the wild-type strain, the nifA mutant produced more nodules than the wild-type that clustered into regularly-patterned root zones. Mutation of the iaaMH genes in a nifA mutant background reduced the presence of these nodule clusters on the root. We further show that the P. phymatum iaaMH genes are located in a region of the symbiotic plasmid with a significantly lower GC content and exhibit high similarity to two genes of the IAM pathway often used by bacterial phytopathogens to deploy IAA as a virulence factor. Overall, our data suggest that the increased abundance of rhizobial auxin in the non-fixing nifA mutant strain enables greater root infection rates and a role for bacterial auxin production in the control of early stage symbiotic interactions.

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Section: Discussionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

A novel function of the key nitrogen-fixation activator NifA in beta-rhizobia: Repression of bacterial auxin synthesis during symbiosis

Bellés-Sancho

Liu²,

Heiniger³

et al. 2022

Front. Plant Sci.

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“…The application of 50 mg/L K-humate showed superior effects compared with the control in relation to the total root length, number and weight of nodules, and N input . The total root surface area and volume of rice presented a greater stimulation response when humic aid was applied at 80 mg/L …”

Section: Discussionmentioning

confidence: 92%

Transcriptomic and Metabolomic Analysis of Soybean Nodule Number Improvements with the Use of Water-Soluble Humic Materials

Zhang

Hou

Zhang

et al. 2022

J. Agric. Food Chem.

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Water-soluble humic materials (WSHMs) can enhance the nodule numbers of soybean plants. In this study, targeted metabolomics and transcriptomics were used to understand this mechanism. Results showed that 500 mg/L WSHM increased the adsorption and colonization of rhizobia in soybean roots. High-performance liquid chromatography and targeted metabolomics showed that WSHMs could regulate the content and distribution of endogenous hormones of soybean plants at the initial stage of soybean nodulation. Transcriptomic analysis showed a total of 2406 differentially expressed genes (DEGs) by the 25th day, accounting for 4.89% of total annotation genes (49159). These DEGs were found to contribute primarily to the MAPK signaling pathway, glycolysis/gluconeogenesis, and plant hormone signal transduction according to the −log 10 (Padjust) value in the KEGG pathway. Subsequently, DEGs related to these hormones were selected for verification using quantity-PCR. The WSHM increased the number of nodules by regulating the expression of endogenous hormones in soybean plants.

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“…Other examples where pea genes have provided valuable insights into important physiological processes include the identification of the branching hormone, strigolactone ( Gomez-Roldan et al, 2008) , and its associated biosynthetic and perception pathways (see Mashiguchi et al, 2021 ). Pea is also proving to be a key model species for genetic studies on plant–microbe interactions during symbioses such as nodulation and arbuscular mycorrhizae ( Foo et al, 2013 ; Velandia et al, 2022 ), phenomena that do not occur in Arabidopsis.…”

Section: Progress With Molecular Tools and Resources For Pea As A Mod...mentioning

confidence: 99%

“…Key discoveries in pea have been made recently on phenomena such as the regulation of flowering, nodulation, hormone biosynthesis and signaling, branching, and starch production (e.g. Barbier et al, 2019 ; Meitzel et al, 2021 ; Velandia et al, 2022 ; Williams et al, 2022 ). Pea also continues to attract attention as an important temperate crop, due to its ability to fix nitrogen and the high quality and quantity of protein in its seeds for both human and animal consumption.…”

Section: Introductionmentioning

confidence: 99%

Mendel: From genes to genome

2022

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Two hundred years after the birth of Gregor Mendel, it is an appropriate time to reflect on recent developments in the discipline of genetics, particularly advances relating to the prescient friar’s model species, the garden pea (Pisum sativum L.). Mendel’s study of seven characteristics established the laws of segregation and independent assortment. The genes underlying four of Mendel’s loci (A, LE, I and R) have been characterised at the molecular level for over a decade. However, the three remaining genes, influencing pod colour (GP), pod form (V/P) and the position of flowers (FA/FAS), have remained elusive for a variety of reasons, including a lack of detail regarding the loci with which Mendel worked. Here we discuss potential candidate genes for these characteristics, in light of recent advances in the genetic resources for pea. These advances, including the pea genome sequence and reverse-genetics techniques, have revitalised pea as an excellent model species for physiological-genetic studies. We also discuss the issues that have been raised with Mendel’s results, such as the recent controversy regarding the discrete nature of the characters that Mendel chose and the perceived overly-good fit of his segregations to his hypotheses. We also consider the relevance of these controversies to his lasting contribution. Finally, we discuss the use of Mendel’s classical results to teach and enthuse future generations of geneticists, not only regarding the core principles of the discipline, but also its history and the role of hypothesis testing.

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

Cited by 27 publications

References 134 publications

A novel function of the key nitrogen-fixation activator NifA in beta-rhizobia: Repression of bacterial auxin synthesis during symbiosis

A novel function of the key nitrogen-fixation activator NifA in beta-rhizobia: Repression of bacterial auxin synthesis during symbiosis

Transcriptomic and Metabolomic Analysis of Soybean Nodule Number Improvements with the Use of Water-Soluble Humic Materials

Mendel: From genes to genome

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