The expression of LjROP4 is required for rhizobial infection in Lotus japonicus

2019 ◽  
Vol 99 (6) ◽  
pp. 897-904
Author(s):  
Danxia Ke ◽  
Kunpeng Peng
Keyword(s):  
Vascular Bundle ◽  
Root Hair ◽  
Molecular Mechanisms ◽  
Lotus Japonicus ◽  
Gus Activity ◽  
Nodule Development ◽  
Root Tip ◽  
Symbiotic Interaction ◽  
Lateral Root Primordia ◽  
Root Hair Deformation

Increasing evidence suggests that Rho of plant (ROP) GTPases play important roles in the rhizobium–legume symbiotic nodulation, but the molecular mechanisms of their regulation in symbiosis remain poorly understood. In this study, we showed that ROP4 in Lotus japonicus (LjROP4) is involved in the symbiotic interaction between L. japonicus and Mesorhizobium loti. Tissue expression analysis showed that LjROP4 expressed highly in the root. Histochemical staining analysis showed that after rhizobia inoculation, GUS reporter activity increased in the root vascular bundle, root tip, and lateral root primordia. During nodule development, GUS activity was detected in the cortex of nodule primordia and young nodules. In the mature nodules, GUS activity was detected only in the vascular bundle. Compared with the control, the overexpression of ROP4 and ROP4-CA produced much more pronounced root hair swelling and curling induced by M. loti. The infection event and nodule number noticeably increased, which was consistent with this promotion of root hair deformation. Moreover, RNA interference of LjROP4 produced opposite phenotypes. These data suggest that LjROP4 is required for root hair deformation during rhizobial infection. Thus, our study provides important information about root hair deformation responses induced by nod factors in the early stages of symbiotic interaction.

scholarly journals Identification of Symbiotically Defective Mutants of Lotus japonicus Affected in Infection Thread Growth

2006 ◽  
Vol 19 (12) ◽  
pp. 1444-1450 ◽  
Author(s):  
Fabien Lombardo ◽  
Anne B. Heckmann ◽  
Hiroki Miwa ◽  
Jillian A. Perry ◽  
Koji Yano ◽  
...  
Keyword(s):  
Root Hair ◽  
Plant Cell Wall ◽  
Plant Root ◽  
Lotus Japonicus ◽  
Cortical Cell ◽  
Host Cells ◽  
Infection Thread ◽  
Mycorrhizal Symbiosis ◽  
Symbiotic Interaction ◽  
Infection Threads

During the symbiotic interaction between legumes and rhizobia, the host cell plasma membrane and associated plant cell wall invaginate to form a tunnel-like infection thread, a structure in which bacteria divide to reach the plant root cortex. We isolated four Lotus japonicus mutants that make infection pockets in root hairs but form very few infection threads after inoculation with Mesorhizobium loti. The few infection threads that did initiate in the mutants usually did not progress further than the root hair cell. These infection-thread deficient (itd) mutants were unaffected for early symbiotic responses such as calcium spiking, root hair deformation, and curling, as well as for the induction of cortical cell division and the arbuscular mycorrhizal symbiosis. Complementation tests and genetic mapping indicate that itd2 is allelic to Ljsym7, whereas the itd1, itd3, and itd4 mutations identified novel loci. Bacterial release into host cells did occur occasionally in the itd1, itd2, and itd3 mutants suggesting that some infections may succeed after a long period and that infection of nodule cells could occur normally if the few abnormal infection threads that were formed reached the appropriate nodule cells.

scholarly journals Development of Ectopic Roots from Abortive Nodule Primordia

2004 ◽  
Vol 17 (10) ◽  
pp. 1043-1050 ◽  
Author(s):  
Simona Ferraioli ◽  
Rosarita Tatè ◽  
Alessandra Rogato ◽  
Maurizio Chiurazzi ◽  
Eduardo J. Patriarca
Keyword(s):  
Root Hair ◽  
Nodule Development ◽  
Bacterial Invasion ◽  
Meristematic Tissue ◽  
Root Hair Deformation ◽  
Conditional Mutant ◽  
Infection Threads ◽  
Induced Mutants ◽  
Symbiotic Phenotype ◽  
Nodulin Genes

The symbiotic phenotype of five Tn5-induced mutants of Rhizobium etli affected in different anabolic pathways (namely, gluconeogenesis and biosynthesis of lysine, purine, or pyrimidine) was analyzed. These mutants induced, on the root of Phaseolus vulgaris, a normal early sequence of morphogenetics events, including root hair deformation and development of nodule primordia. Later on, however, from the resulting root outgrowths, instead of nodules, one or more ectopic roots (spaced closely related and agravitropic) emerged. Therefore, this group of mutant was collectively called “root inducer” (RIND). It was observed that the RIND-induced infection threads aborted early inside the invaded root hair, and that the resulting abortive nodules lack induction of late nodulin genes. Moreover, experiments performed using a conditional mutant (a methionine-requiring invader) revealed that bacterial invasion plays a key role in the maintenance of the program of nodule development and, in particular, in the differentiation of the most specific symbiotic tissue of globose nodules, the central tissue. These data indicate that, in P. vulgaris, the nodule primordium is a root-specified pro-meristematic tissue.

ROP6 is involved in root hair deformation induced by Nod factors in Lotus japonicus

2016 ◽  
Vol 108 ◽  
pp. 488-498 ◽  
Author(s):  
Danxia Ke ◽  
Xiangyong Li ◽  
Yapeng Han ◽  
Lin Cheng ◽  
Hongyu Yuan ◽  
...  
Keyword(s):  
Root Hair ◽  
Lotus Japonicus ◽  
Nod Factors ◽  
Root Hair Deformation

scholarly journals The Lotus japonicus LjSym4 Gene Is Required for the Successful Symbiotic Infection of Root Epidermal Cells

2000 ◽  
Vol 13 (10) ◽  
pp. 1109-1120 ◽  
Author(s):  
Paola Bonfante ◽  
Andrea Genre ◽  
Antonella Faccio ◽  
Isabella Martini ◽  
Leif Schauser ◽  
...  
Keyword(s):  
Root Hair ◽  
Glomus Intraradices ◽  
Lotus Japonicus ◽  
Am Fungi ◽  
Epidermal Cells ◽  
Parental Line ◽  
Entry Site ◽  
Symbiotic Interaction ◽  
Successful Infection ◽  
Infection Threads

The role of the Lotus japonicus LjSym4 gene during the symbiotic interaction with Mesorhizobium loti and arbuscular mycorrhizal (AM) fungi was analyzed with two mutant alleles conferring phenotypes of different strength. Ljsym4-1 and Ljsym4-2 mutants do not form nodules with M. loti.Normal root hair curling and infection threads are not observed, while a nodC-dependent deformation of root hair tips indicates that nodulation factors are still perceived by Ljsym4 mutants. Fungal infection attempts on the mutants generally abort within the epidermis, but Ljsym4-1 mutants allow rare, successful, infection events, leading to delayed arbuscule formation. On roots of mutants homozygous for the Ljsym4-2 allele, arbuscule formation was never observed upon inoculation with either of the two AM fungi, Glomus intraradices or Gigaspora margarita. The strategy of epidermal penetration by G. margarita was identical for Ljsym4-2 mutants and the parental line, with appressoria, hyphae growing between two epidermal cells, penetration of epidermal cells through their anticlinal wall. These observations define a novel, genetically controlled step in AM colonization. Although rhizobia penetrate the tip of root hairs and AM fungi access an entry site near the base of epidermal cells, the LjSym4 gene is necessary for the appropriate response of this cell type to both microsymbionts. We propose that LjSym4 is required for the initiation or coordinated expression of the host plant cell's accommodation program, allowing the passage of both microsymbionts through the epidermis layer.

scholarly journals New Nodulation Mutants Responsible for Infection Thread Development in Lotus japonicus

2006 ◽  
Vol 19 (7) ◽  
pp. 801-810 ◽  
Author(s):  
Koji Yano ◽  
Myra L. Tansengco ◽  
Taihei Hio ◽  
Kuniko Higashi ◽  
Yoshikatsu Murooka ◽  
...  
Keyword(s):  
Developmental Process ◽  
Lotus Japonicus ◽  
Infection Thread ◽  
Nodule Development ◽  
Short Root ◽  
Symbiotic Interaction ◽  
Model Legume ◽  
Infection Threads ◽  
Nodulation Mutants ◽  
Legume Plants

Legume plants develop specialized root organs, the nodules, through a symbiotic interaction with rhizobia. The developmental process of nodulation is triggered by the bacterial microsymbiont but regulated systemically by the host legume plants. Using ethylmethane sulfonate mutagenesis as a tool to identify plant genes involved in symbiotic nodule development, we have isolated and analyzed five nodulation mutants, Ljsym74-3, Ljsym79-2, Ljsym79-3, Ljsym80, and Ljsym82, from the model legume Lotus japonicus. These mutants are defective in developing functional nodules and exhibit nitrogen starvation symptoms after inoculation with Mesorhizobium loti. Detailed observation revealed that infection thread development was aborted in these mutants and the nodules formed were devoid of infected cells. Mapping and complementation tests showed that Ljsym74-3, and Ljsym79-2 and Ljsym79-3, were allelic with reported mutants of L. japonicus, alb1 and crinkle, respectively. The Ljsym82 mutant is unique among the mutants because the infection thread was aborted early in its development. Ljsym74-3 and Ljsym80 were characterized as mutants with thick infection threads in short root hairs. Map-based cloning and molecular characterization of these genes will help us understand the genetic mechanism of infection thread development in L. japonicus.

scholarly journals Analysis of Nod-Factor-Induced Calcium Signaling in Root Hairs of Symbiotically Defective Mutants of Lotus japonicus

2006 ◽  
Vol 19 (8) ◽  
pp. 914-923 ◽  
Author(s):  
Hiroki Miwa ◽  
Jongho Sun ◽  
Giles E. D. Oldroyd ◽  
J. Allan Downie
Keyword(s):  
Calcium Influx ◽  
Lotus Japonicus ◽  
Root Hairs ◽  
Calcium Flux ◽  
Symbiotic Interaction ◽  
Nod Factor ◽  
Root Hair Deformation ◽  
Complementation Groups ◽  
Calcium Spiking ◽  
Timing Of Initiation

Nodulation (Nod)-factor signaling molecules are essential for rhizobia to initiate the nitrogen-fixing symbiotic interaction with legumes. Using a dual dye ratiometric calcium imaging technique, we have shown that 10 nM Nod factor added to roots of Lotus japonicus seedlings induces an intra-cellular calcium increase (calcium flux) that precedes oscillations in intracellular calcium (calcium spiking). The calcium flux was not observed with 1 or 0.1 nM Nod factor, which did induce calcium spiking. The calcium flux was variable in timing of initiation and duration and was observed in approximately half of the root hairs examined. Representatives from 11 complementation groups of symbiotically defective mutants were analyzed for the calcium flux. Mutants from four groups (sym6, ccamk, sym35, and nin) which retained calcium spiking all showed a normal calcium flux. Two classes of mutants (nfr1 and nfr5) lacked both calcium influx and calcium spiking, whereas five classes of mutants (symRK, castor, pollux, nup133, and sym24) defective for calcium spiking retained a calcium flux. There was no correlation between calcium spiking and induction of root hair deformation by Nod factor. We propose that increased bacterial numbers within infection foci in root hairs leads to accumulation of Nod factor to sufficient levels to activate the calcium flux, and this may drive infection thread growth.

scholarly journals GmYUC2a mediates auxin biosynthesis during root development and nodulation in soybean

2019 ◽  
Vol 70 (12) ◽  
pp. 3165-3176 ◽  
Author(s):  
Youning Wang ◽  
Wei Yang ◽  
Yanyan Zuo ◽  
Lin Zhu ◽  
April H Hastwell ◽  
...  
Keyword(s):  
Root Development ◽  
Root Hair ◽  
Root Hairs ◽  
Auxin Biosynthesis ◽  
Nodule Development ◽  
Nodule Formation ◽  
Growth Defects ◽  
Auxin Production ◽  
Primary Roots ◽  
Root Hair Deformation

Abstract Auxin plays central roles in rhizobial infection and nodule development in legumes. However, the sources of auxin during nodulation are unknown. In this study, we analyzed the YUCCA (YUC) gene family of soybean and identified GmYUC2a as an important regulator of auxin biosynthesis that modulates nodulation. Following rhizobial infection, GmYUC2a exhibited increased expression in various nodule tissues. Overexpression of GmYUC2a (35S::GmYUC2a) increased auxin production in soybean, resulting in severe growth defects in root hairs and root development. Upon rhizobial infection, 35S::GmYUC2a hairy roots displayed altered patterns of root hair deformation and nodule formation. Root hair deformation occurred mainly on primary roots, and nodules formed exclusively on primary roots of 35S::GmYUC2a plants. Moreover, transgenic 35S::GmYUC2a composite plants showed delayed nodule development and a reduced number of nodules. Our results suggest that GmYUC2a plays an important role in regulating both root growth and nodulation by modulating auxin balance in soybean.

Ultrastructure of Medicago sativa rhizodermis cells over their early development

Biologia ◽  
2008 ◽  
Vol 63 (2) ◽  
Author(s):  
Lucia Mikolajová ◽  
Halina Vargová ◽  
Zora Hanáčková ◽  
Milada Čiamporová
Keyword(s):  
Cell Wall ◽  
Medicago Sativa ◽  
Root Hair ◽  
Phosphotungstic Acid ◽  
Root Tip ◽  
Cell Wall Polysaccharides ◽  
Golgi Bodies ◽  
Internalization Process ◽  
Subcellular Level ◽  
Root Hair Initiation

AbstractUltrastructure was investigated along the files of developing epidermal cells in the root tip of a model plant Medicago sativa, in which all rhizodermal cells are potential hair-forming trichoblasts. Differentiation at subcellular level was observed up to the stage of bulge initiation in the trichoblasts. Root hair initiation indicated by the emergence of bulges from trichoblasts was detected at various distances from the root tip and, it was independent of the trichoblast size.During rhizodermal cell differentiation, starch grains accumulated in the plastids. Nuclei located in the central part of the young, meristematic cells moved towards the inner periclinal wall as the central vacuole enlarged. The bulging region of the trichoblasts located opposite the nucleus and was rich in mitochondria, ER, ribosomes, and Golgi bodies, and contained also vesicles enclosing fibrillar material. This material responded positively to phosphotungstic acid, which was used for detection of cell wall polysaccharides. The cell wall thickness within the bulging domain was significantly lower than in other parts of trichoblasts. We suggest that internalization of cell wall polysaccharides occurs within the bulging area, contributing to local thinning of the cell wall and providing a source of osmotically active compounds for maintaining turgor in the trichoblast. Thus, the internalization process might be necessary for root hair outgrowth.

Root hair deformation in the infection process of Alnus rubra

1983 ◽  
Vol 61 (11) ◽  
pp. 2863-2876 ◽  
Author(s):  
Alison M. Berry ◽  
John G. Torrey
Keyword(s):  
Root Hair ◽  
Cell Walls ◽  
Root Hairs ◽  
Infection Process ◽  
Alnus Rubra ◽  
Pseudomonas Cepacia ◽  
Developmental Studies ◽  
Experimental Conditions ◽  
Root Hair Cell ◽  
Root Hair Deformation

Structural and cell developmental studies of root hair deformation in Alnus rubra Bong. (Betulaceae) were carried out following inoculation with the soil pseudomonad Pseudomonas cepacia 85, alone or in concert with Frankia, and using axenically grown seedlings. Deformational changes can be observed in elongating root hairs within 2 h of inoculation with P. cepacia 85. These growing root hairs become branched or multilobed and highly modified from the single-tip growth of axenic root hairs. The cell walls of deformed hairs are histologically distinctive when stained with the fluorochrome acridine orange. Filtrate studies using P. cepacia 85 suggest that the deforming substance is not a low molecular weight compound. Root hair deformation and the associated wall histology are host specific in that Betula root hairs show none of these responses when grown and inoculated in the experimental conditions described. The bacterially induced changes in root hair cell walls during deformation may create a chemically and physically modified substrate for Frankia penetration, and the deformation itself may serve to entrap and enclose the filamentous organism, allowing wall dissolution and entry. Thus these events represent a complex host response as a precondition to successful nodulation.

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