Research note: Shoot control of hypernodulation and aberrant root formation in the har1-1 mutant of Lotus japonicus

2002 ◽  
Vol 29 (11) ◽  
pp. 1371 ◽  
Author(s):  
Qunyi Jiang ◽  
Peter M. Gresshoff
Keyword(s):  
Root Growth ◽  
Root Formation ◽  
Lotus Japonicus ◽  
Dna Amplification ◽  
Genetic Alteration ◽  
Research Note ◽  
Wild Type ◽  
Mesorhizobium Loti ◽  
Mutant Locus ◽  
Nodule Morphology

The har1-1 mutant of Lotus japonicus B-129-S9 Gifu is characterized by two phenotypes: greater than normal nodulation (hypernodulation) and significantly inhibited root growth in the presence of its microsymbiont Mesorhizobium loti strain NZP2235. We demonstrate that the two traits co-segregate, suggesting a single genetic alteration involving developmental pleiotropy. A cross between the mutant and genotype Funakura (with wild-type root and nodule morphology) demonstrated Mendelian recessive segregation of both phenotypes (root and nodule) in 216 F2 individuals. Using DNA-amplification fingerprinting polymorphisms in Gifu har1-1 and Funakura, the mutant locus was positioned between two markers at about 7 and 13 cM distance. Reciprocal hypocotyl grafting of shoots and roots showed that the hypernodulation and reduced root phenotypes are both predominantly controlled by the shoot.

scholarly journals Defects in Rhizobial Cyclic Glucan and Lipopolysaccharide Synthesis Alter Legume Gene Expression During Nodule Development

2008 ◽  
Vol 21 (1) ◽  
pp. 50-60 ◽  
Author(s):  
Alejandra L. D'Antuono ◽  
Thomas Ott ◽  
Lene Krusell ◽  
Vera Voroshilova ◽  
Rodolfo A. Ugalde ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mutant Strain ◽  
Early Recognition ◽  
Lotus Japonicus ◽  
Cdna Array ◽  
Nodule Development ◽  
Marker Genes ◽  
Wild Type ◽  
Mesorhizobium Loti ◽  
Expression Of Genes

cDNA array technology was used to compare transcriptome profiles of Lotus japonicus roots inoculated with a Mesorhizobium loti wild-type and two mutant strains affected in cyclic β(1-2) glucan synthesis (cgs) and in lipopolysaccharide synthesis (lpsβ2). Expression of genes associated with the development of a fully functional nodule was significantly affected in plants inoculated with the cgs mutant. Array results also revealed that induction of marker genes for nodule development was delayed when plants were inoculated with the lpsβ2 mutant. Quantitative real-time reverse-transcriptase polymerase chain reaction was used to quantify gene expression of a subset of genes involved in plant defense response, redox metabolism, or genes that encode for nodulins. The majority of the genes analyzed in this study were more highly expressed in roots inoculated with the wild type compared with those inoculated with the cgs mutant strain. Some of the genes exhibited a transient increase in transcript levels during intermediate steps of normal nodule development while others displayed induced expression during the final steps of nodule development. Ineffective nodules induced by the glucan mutant showed higher expression of phenylalanine ammonia lyase than wild-type nodules. Differences in expression pattern of genes involved in early recognition and signaling were observed in plants inoculated with the M. loti mutant strain affected in the synthesis of cyclic glucan.

scholarly journals A Novel Fix¯ Symbiotic Mutant of Lotus japonicus, Ljsym105, Shows Impaired Development and Premature Deterioration of Nodule Infected Cells and Symbiosomes

2006 ◽  
Vol 19 (7) ◽  
pp. 780-788 ◽  
Author(s):  
Md. Shakhawat Hossain ◽  
Yosuke Umehara ◽  
Hiroshi Kouchi
Keyword(s):  
Nitrogen Deficiency ◽  
Lotus Japonicus ◽  
Nodule Development ◽  
Acetylene Reduction Activity ◽  
Nitrogen Fixing ◽  
Wild Type ◽  
Electron Microscopic ◽  
Model Legume ◽  
Mesorhizobium Loti ◽  
Infected Cells

Nitrogen-fixing symbiosis between legume plants and rhizobia is established through complex interactions between two symbiotic partners. To identify the host legume genes that play crucial roles in such interactions, we isolated a novel Fix¯ mutant, Ljsym105, from a model legume Lotus japonicus MG-20. The Ljsym105 plants displayed nitrogen-deficiency symptoms after inoculation with Mesorhizobium loti under nitrogen-free conditions, but their growth recovered when supplied with nitrogen-rich nutrients. Ljsym105 was recessive and monogenic and mapped on the upper portion of chromosome 4. The mutant Ljsym105 formed an increased number of small and pale-pink nodules. Nitrogenase (acetylene reduction) activity per nodule fresh weight was low but retained more than 50% of that of the wild-type nodules. Light and electron microscopic observations revealed that the Ljsym105 nodule infected cells were significantly smaller than those of wild-type plants, contained enlarged symbiosomes with multiple bacteroids, and underwent deterioration of the symbiosomes prematurely as well as disintegration of the whole infected cell cytoplasm. These results indicate that the ineffectiveness of the Ljsym105 nodules is primarily due to impaired growth of infected cells accompanied with the premature senescence induced at relatively early stages of nodule development. These symbiotic phenotypes are discussed in respect to possible functions of the LjSym105 locus in the symbiotic interactions required for establishment of the nitrogen-fixing symbiosis.

scholarly journals Mutants of Lotus japonicus deficient in flavonoid biosynthesis

2021 ◽  
Vol 134 (2) ◽  
pp. 341-352
Author(s):  
Toshio Aoki ◽  
Masayoshi Kawaguchi ◽  
Haruko Imaizumi-Anraku ◽  
Shoichiro Akao ◽  
Shin-ichi Ayabe ◽  
...  
Keyword(s):  
Anthocyanin Biosynthesis ◽  
Lotus Japonicus ◽  
Flavonoid Biosynthesis ◽  
Anthocyanin Accumulation ◽  
Type B ◽  
Wild Type ◽  
Ems Mutagenesis ◽  
Model Legume ◽  
Mesorhizobium Loti ◽  
Wild Accessions

AbstractSpatiotemporal features of anthocyanin accumulation in a model legumeLotus japonicus(Regel) K.Larsen were elucidated to develop criteria for the genetic analysis of flavonoid biosynthesis. Artificial mutants and wild accessions, with lower anthocyanin accumulation in the stem than the standard wild type (B-129 ‘Gifu’), were obtained by ethyl methanesulfonate (EMS) mutagenesis and from a collection of wild-grown variants, respectively. The loci responsible for the green stem of the mutants were named asVIRIDICAULIS(VIC). Genetic and chemical analysis identified two loci, namely,VIC1andVIC2, required for the production of both anthocyanins and proanthocyanidins (condensed tannins), and two loci, namely,VIC3andVIC4, required for the steps specific to anthocyanin biosynthesis. A mutation inVIC5significantly reduced the anthocyanin accumulation. These mutants will serve as a useful system for examining the effects of anthocyanins and proanthocyanidins on the interactions with herbivorous pests, pathogenic microorganisms and nitrogen-fixing symbiotic bacteria,Mesorhizobium loti.

scholarly journals Functional Differences of Two Distinct Catalases in Mesorhizobium loti MAFF303099 under Free-Living and Symbiotic Conditions

2008 ◽  
Vol 191 (5) ◽  
pp. 1463-1471 ◽  
Author(s):  
Masaki Hanyu ◽  
Hanae Fujimoto ◽  
Kouhei Tejima ◽  
Kazuhiko Saeki
Keyword(s):  
Stationary Phase ◽  
Generation Time ◽  
Expression Profiles ◽  
Lotus Japonicus ◽  
Living Conditions ◽  
Exponential Growth Phase ◽  
Wild Type ◽  
Free Living ◽  
Mesorhizobium Loti ◽  
Free Living Conditions

ABSTRACT Protection against reactive oxygen species (ROS) is important for legume-nodulating rhizobia during the establishment and maintenance of symbiosis, as well as under free-living conditions, because legume hosts might assail incoming microbes with ROS and because nitrogenase is extremely sensitive to ROS. We generated mutants of two potential catalase genes in Mesorhizobium loti MAFF303099 to investigate their physiological significance. Biochemical results indicated that genes with the locus tags mlr2101 and mlr6940 encoded a monofunctional catalase and a bifunctional catalase-peroxidase, respectively, that were named katE and katG. Under free-living conditions, the katG mutant demonstrated an extended generation time and elevated sensitivity to exogenous H2O2, whereas the katE mutant exhibited no generation time extension and only a slight increase in sensitivity to exogenous H2O2. However, the katE mutant showed a marked decrease in its survival rate during the stationary phase. With regard to symbiotic capacities with Lotus japonicus, the katG mutant was indistinguishable from the wild type; nevertheless, the mutants with disrupted katE formed nodules with decreased nitrogen fixation capacities (about 50 to 60%) compared to those formed by the wild type. These mutant phenotypes agreed with the expression profiles showing that transcription of katG, but not katE, was high during the exponential growth phase and that transcription levels of katE versus sigA were elevated during stationary phase and were approximately fourfold higher in bacteroids than mid-exponential-phase cells. Our results revealed functional separation of the two catalases, as well as the importance of KatE under conditions of strong growth limitation.

scholarly journals Low ABA concentration promotes root growth and hydrotropism through relief of ABA INSENSITIVE 1-mediated inhibition of plasma membrane H+-ATPase 2

2021 ◽  
Vol 7 (12) ◽  
pp. eabd4113
Author(s):  
Rui Miao ◽  
Wei Yuan ◽  
Yue Wang ◽  
Irene Garcia-Maquilon ◽  
Xiaolin Dang ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Root Growth ◽  
Experimental System ◽  
Aba Signaling ◽  
Wild Type ◽  
Normal Medium ◽  
C Terminus ◽  
Quadruple Mutant ◽  
Aba Insensitive ◽  
Aba Receptors

The hab1-1abi1-2abi2-2pp2ca-1 quadruple mutant (Qabi2-2) seedlings lacking key negative regulators of ABA signaling, namely, clade A protein phosphatases type 2C (PP2Cs), show more apoplastic H+ efflux in roots and display an enhanced root growth under normal medium or water stress medium compared to the wild type. The presence of low ABA concentration (0.1 micromolar), inhibiting PP2C activity via monomeric ABA receptors, enhances root apoplastic H+ efflux and growth of the wild type, resembling the Qabi2-2 phenotype in normal medium. Qabi2-2 seedlings also demonstrate increased hydrotropism compared to the wild type in obliquely-oriented hydrotropic experimental system, and asymmetric H+ efflux in root elongation zone is crucial for root hydrotropism. Moreover, we reveal that Arabidopsis ABA-insensitive 1, a key PP2C in ABA signaling, interacts directly with the C terminus of Arabidopsis plasma membrane H+-dependent adenosine triphosphatase 2 (AHA2) and dephosphorylates its penultimate threonine residue (Thr947), whose dephosphorylation negatively regulates AHA2.

scholarly journals Constitutive Photomorphogenic 1 Enhances ER Stress Tolerance in Arabidopsis

2021 ◽  
Vol 22 (19) ◽  
pp. 10772
Author(s):  
Chang Ho Kang ◽  
Eun Seon Lee ◽  
Ganesh M. Nawkar ◽  
Joung Hun Park ◽  
Seong Dong Wi ◽  
...  
Keyword(s):  
Stress Response ◽  
Er Stress ◽  
Stress Conditions ◽  
Negative Regulator ◽  
Light Signaling ◽  
Dependent Manner ◽  
Wild Type ◽  
Er Stress Response ◽  
The Unfolded Protein Response ◽  
Mutant Locus

Interaction between light signaling and stress response has been recently reported in plants. Here, we investigated the role of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), a key regulator of light signaling, in endoplasmic reticulum (ER) stress response in Arabidopsis. The cop1-4 mutant Arabidopsis plants were highly sensitive to ER stress induced by treatment with tunicarmycin (Tm). Interestingly, the abundance of nuclear-localized COP1 increased under ER stress conditions. Complementation of cop1-4 mutant plants with the wild-type or variant types of COP1 revealed that the nuclear localization and dimerization of COP1 are essential for its function in plant ER stress response. Moreover, the protein amount of ELONGATED HYPOCOTYL 5 (HY5), which inhibits bZIP28 to activate the unfolded protein response (UPR), decreased under ER stress conditions in a COP1-dependent manner. Accordingly, the binding of bZIP28 to the BIP3 promoter was reduced in cop1-4 plants and increased in hy5 plants compared with the wild type. Furthermore, introduction of the hy5 mutant locus into the cop1-4 mutant background rescued its ER stress-sensitive phenotype. Altogether, our results suggest that COP1, a negative regulator of light signaling, positively controls ER stress response by partially degrading HY5 in the nucleus.

scholarly journals Lateral Root Priming Synergystically Arises from Root Growth and Auxin Transport Dynamics

2018 ◽  
Author(s):  
Thea van den Berg ◽  
Kirsten H. ten Tusscher
Keyword(s):  
Cell Cycle ◽  
Root Growth ◽  
Lateral Root ◽  
Root Formation ◽  
Growth Dynamics ◽  
Root Tip ◽  
Cycle Duration ◽  
Elongation Zone ◽  
Lateral Root Formation ◽  
Cell Cycle Duration

AbstractThe root system is a major determinant of plant fitness. Its capacity to supply the plant with sufficient water and nutrients strongly depends on root system architecture, which arises from the repeated branching off of lateral roots. A critical first step in lateral root formation is priming, which prepatterns sites competent of forming a lateral root. Priming is characterized by temporal oscillations in auxin, auxin signalling and gene expression in the root meristem, which through growth become transformed into a spatially repetitive pattern of competent sites. Previous studies have demonstrated the importance of auxin synthesis, transport and perception for the amplitude of these oscillations and their chances of producing an actual competent site. Additionally, repeated lateral root cap apoptosis was demonstrated to be strongly correlated with repetitive lateral root priming. Intriguingly, no single mutation has been identified that fully abolishes lateral root formation, and thusfar the mechanism underlying oscillations has remained unknown. In this study, we investigated the impact of auxin reflux loop properties combined with root growth dynamics on priming, using a computational approach. To this end we developed a novel multi-scale root model incorporating a realistic root tip architecture and reflux loop properties as well as root growth dynamics. Excitingly, in this model, repetitive auxin elevations automatically emerge. First, we show that root tip architecture and reflux loop properties result in an auxin loading zone at the start of the elongation zone, with preferential auxin loading in narrow vasculature cells. Second, we demonstrate how meristematic root growth dynamics causes regular alternations in the sizes of cells arriving at the elongation zone, which subsequently become amplified during cell expansion. These cell size differences translate into differences in cellular auxin loading potential. Combined, these properties result in temporal and spatial fluctuations in auxin levels in vasculature and pericycle cells. Our model predicts that temporal priming frequency predominantly depends on cell cycle duration, while cell cycle duration together with meristem size control lateral root spacing.

scholarly journals ALotus japonicusE3 ligase interacts with the Nod factor receptor 5 and positively regulates nodulation

2018 ◽  
Author(s):  
Daniela Tsikou ◽  
Estrella E. Ramirez ◽  
Ioanna S. Psarrakou ◽  
Jaslyn E. Wong ◽  
Dorthe B. Jensen ◽  
...  
Keyword(s):  
Lotus Japonicus ◽  
E3 Ligase ◽  
Kinase Domain ◽  
Plant Interactions ◽  
Post Translational Modification ◽  
Direct Role ◽  
Nod Factor ◽  
Mesorhizobium Loti ◽  
Signaling Systems ◽  
Nodulation Capacity

SUMMARYPost-translational modification of receptor proteins is involved in activation and de-activation of signaling systems in plants. Both ubiquitination and deubiquitination have been implicated in plant interactions with pathogens and symbionts. Here we presentLjPUB13, a PUB-ARMADILLO repeat E3 ligase that specifically ubiquitinates the kinase domain of the Nod Factor receptor NFR5 and has a direct role in nodule organogenesis events inLotus japonicus. Phenotypic analyses of three LORE1 retroelement insertion plant lines revealed thatpub13plants display delayed and reduced nodulation capacity and retarded growth.LjPUB13expression is spatially regulated during symbiosis withMesorhizobium loti, with increased levels in young developing nodules. Thus,LjPUB13 is an E3 ligase with a positive regulatory role during the initial stages of nodulation inL. japonicus.

scholarly journals Lotus japonicus Contains Two Distinct ENOD40 Genes That Are Expressed in Symbiotic, Nonsymbiotic, and Embryonic Tissues

2000 ◽  
Vol 13 (9) ◽  
pp. 987-994 ◽  
Author(s):  
Emmanouil Flemetakis ◽  
Nektarios Kavroulakis ◽  
Nicolette E. M. Quaedvlieg ◽  
Herman P. Spaink ◽  
Maria Dimou ◽  
...  
Keyword(s):  
Root Nodule ◽  
Vascular System ◽  
Lotus Japonicus ◽  
Mrna Accumulation ◽  
Mesorhizobium Loti ◽  
Embryonic Tissues ◽  
Early Nodulin ◽  
Gene Transcripts ◽  
Young Seed

ENOD40, an early nodulin gene, has been postulated to play a significant role in legume root nodule ontogenesis. We have isolated two distinct ENOD40 genes from Lotus japonicus. The transcribed regions of the two ENOD40 genes share 65% homology, while the two promoters showed no significant homology. Both transcripts encode a putative dodecapeptide similar to that identified in other legumes forming determinate nodules. Both ENOD40 genes are coordinately expressed following inoculation of roots with Mesorhizobium loti or treatment with purified Nod factors. In the former case, mRNA accumulation could be detected up to 10 days following inoculation while in the latter case the accumulation was transient. High levels of both ENOD40 gene transcripts were found in nonsymbiotic tissues such as stems, fully developed flowers, green seed pods, and hypocotyls. A relatively lower level of both transcripts was observed in leaves, roots, and cotyledons. In situ hybridization studies revealed that, in mature nodules, transcripts of both ENOD40 genes accumulate in the nodule vascular system; additionally, in young seed pods strong signal is observed in the ovule, particularly in the phloem and epithelium, as well as in globular stage embryos.

Characterisation of three shoot apical meristem mutants of Arabidopsis thaliana

Development ◽  
1992 ◽  
Vol 116 (2) ◽  
pp. 397-403 ◽  
Author(s):  
H. M. Ottoline Leyser ◽  
I. J. Furner
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Growth ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Floral Development ◽  
Wild Type ◽  
Recessive Mutations ◽  
Phenotypic Characterisation ◽  
Dicotyledonous Plants ◽  
And Function

The shoot apical meristem of dicotyledonous plants is highly regulated both structurally and functionally, but little is known about the mechanisms involved in this regulation. Here we describe the genetic and phenotypic characterisation of recessive mutations at three loci of Arabidopsis thaliana in which meristem structure and function are disrupted. The loci are Clavata1 (Clv1), Fasciata1 (Fas1) and Fasciata2 (Fas2). Plants mutant at these loci are fasciated having broad, flat stems and disrupted phyllotaxy. In all cases, the fasciations are associated with shoot apical meristem enlargement and altered floral development. While all the mutants share some phenotypic features they can be divided into two classes. The pleiotropic fas1 and fas2 mutants are unable to initiate wild- type organs, show major alterations in meristem structure and have reduced root growth. In contrast, clv1 mutant plants show near wild-type organ phenotypes, more subtle changes in shoot apical meristem structure and wild-type root growth.

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