AnArabidopsis short root and dwarfism mutant defines a novel locus that mediates both cell division and elongation

2006 ◽  
Vol 49 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Hyun Kyung Lee ◽  
Mi Kwon ◽  
Ji Hyun Jeon ◽  
Shozo Fujioka ◽  
Ho Bang Kim ◽  
...  
Keyword(s):  
2022 ◽  
Vol 119 (3) ◽  
pp. e2108641119
Author(s):  
Chunhua Wang ◽  
Meng Li ◽  
Yang Zhao ◽  
Nengsong Liang ◽  
Haiyang Li ◽  
...  

Nitrogen fixation in soybean takes place in root nodules that arise from de novo cell divisions in the root cortex. Although several early nodulin genes have been identified, the mechanism behind the stimulation of cortical cell division during nodulation has not been fully resolved. Here we provide evidence that two paralogs of soybean SHORT-ROOT (GmSHR) play vital roles in soybean nodulation. Expression of GmSHR4 and GmSHR5 (GmSHR4/5) is induced in cortical cells at the beginning of nodulation, when the first cell divisions occur. The expression level of GmSHR4/5 is positively associated with cortical cell division and nodulation. Knockdown of GmSHR5 inhibits cell division in outer cortical layers during nodulation. Knockdown of both paralogs disrupts the cell division throughout the cortex, resulting in poorly organized nodule primordia with delayed vascular tissue formation. GmSHR4/5 function by enhancing cytokinin signaling and activating early nodulin genes. Interestingly, D-type cyclins act downstream of GmSHR4/5, and GmSHR4/5 form a feedforward loop regulating D-type cyclins. Overexpression of D-type cyclins in soybean roots also enhanced nodulation. Collectively, we conclude that the GmSHR4/5-mediated pathway represents a vital module that triggers cytokinin signaling and activates D-type cyclins during nodulation in soybean.


2020 ◽  
Author(s):  
Yadi Xing ◽  
Nan Wang ◽  
Tianquan Zhang ◽  
Qiuli Zhang ◽  
Dan Du ◽  
...  

Development ◽  
2002 ◽  
Vol 129 (18) ◽  
pp. 4327-4334 ◽  
Author(s):  
Panagiota Mylona ◽  
Paul Linstead ◽  
Rob Martienssen ◽  
Liam Dolan

The primary root of Arabidopsis has a simple cellular organisation. The fixed radial cell pattern results from stereotypical cell divisions that occur in the meristem. Here we describe the characterisation of schizoriza (scz), a mutant with defective radial patterning. In scz mutants, the subepidermal layer (ground tissue) develops root hairs. Root hairs normally only form on epidermal cells of wild-type plants. Moreover, extra periclinal divisions (new wall parallel to surface of the root) occur in the scz root resulting in the formation of supernumerary layers in the ground tissue. Both scarecrow (scr) and short root (shr) suppress the extra periclinal divisions characteristic of scz mutant roots. This results in the formation of a single layered ground tissue in the double mutants. Cells of this layer develop root hairs, indicating that mis-specification of the ground tissue in scz mutants is uncoupled to the cell division defect. This suggests that during the development of the ground tissue SCZ has two distinct roles: (1) it acts as a suppressor of epidermal fate in the ground tissue, and (2) it is required to repress periclinal divisions in the meristem. It may act in the same pathway as SCR and SHR.


2007 ◽  
Vol 21 (17) ◽  
pp. 2196-2204 ◽  
Author(s):  
D. Welch ◽  
H. Hassan ◽  
I. Blilou ◽  
R. Immink ◽  
R. Heidstra ◽  
...  

1964 ◽  
Vol 42 (12) ◽  
pp. 1615-1628 ◽  
Author(s):  
M. V. S. Raju ◽  
T. A. Steeves ◽  
J. M. Naylor

In both indeterminate long roots and determinate short roots of Euphorbia esula L., the promeristem usually consists of three meristematic layers. One of these represents the stelar pole, the second is continuous with the cortex, and the most distal appears to initiate the root cap – epidermis complex. Variations in this pattern are noted. Autoradiographs of apices of roots supplied with thymidine-H3 under field conditions demonstrate the existence of a region of low nuclear incorporation during a 24 or 48 hour period at the summit of the root axis in long roots. This region corresponds to the quiescent center described by previous authors. Short root apices consistently lack such a region. The pattern of nuclear incorporation of thymidine-H3 suggests that cell division is infrequent or absent in the center of the apex of long roots but not of short roots. Quiescence is thus a phenomenon which is superimposed upon the organization of the root apex in this species, and its presence or absence seems to be related to the developmental potentiality of the root. In many long roots the size of this quiescent region exceeds that of the region which may reasonably be designated the promeristem.


Author(s):  
L. M. Lewis

The effects of colchicine on extranuclear microtubules associated with the macronucleus of Paramecium bursaria were studied to determine the possible role that these microtubules play in controlling the shape of the macronucleus. In the course of this study, the ultrastructure of the nuclear events of binary fission in control cells was also studied.During interphase in control cells, the micronucleus contains randomly distributed clumps of condensed chromatin and microtubular fragments. Throughout mitosis the nuclear envelope remains intact. During micronuclear prophase, cup-shaped microfilamentous structures appear that are filled with condensing chromatin. Microtubules are also present and are parallel to the division axis.


Author(s):  
Krishan Awtar

Exposure of cells to low sublethal but mitosis-arresting doses of vinblastine sulfate (Velban) results in the initial arrest of cells in mitosis followed by their subsequent return to an “interphase“-like stage. A large number of these cells reform their nuclear membranes and form large multimicronucleated cells, some containing as many as 25 or more micronuclei (1). Formation of large multinucleate cells is also caused by cytochalasin, by causing the fusion of daughter cells at the end of an otherwise .normal cell division (2). By the repetition of this process through subsequent cell divisions, large cells with 6 or more nuclei are formed.


Author(s):  
Ann Cleary

Microinjection of fluorescent probes into living plant cells reveals new aspects of cell structure and function. Microtubules and actin filaments are dynamic components of the cytoskeleton and are involved in cell growth, division and intracellular transport. To date, cytoskeletal probes used in microinjection studies have included rhodamine-phalloidin for labelling actin filaments and fluorescently labelled animal tubulin for incorporation into microtubules. From a recent study of Tradescantia stamen hair cells it appears that actin may have a role in defining the plane of cell division. Unlike microtubules, actin is present in the cell cortex and delimits the division site throughout mitosis. Herein, I shall describe actin, its arrangement and putative role in cell plate placement, in another material, living cells of Tradescantia leaf epidermis.The epidermis is peeled from the abaxial surface of young leaves usually without disruption to cytoplasmic streaming or cell division. The peel is stuck to the base of a well slide using 0.1% polyethylenimine and bathed in a solution of 1% mannitol +/− 1 mM probenecid.


Author(s):  
Vladimir Popenko ◽  
Natalya Cherny ◽  
Maria Yakovleva

Highly polyploid somatic nucleus (macronucleus) of ciliate Bursaria truncatella under goes severe changes in morphology during cell division. At first, macronucleus (Ma) condences, diminishes in size and turns perpendicular to longitudinal axis of the cell. After short time, Ma turns again, elongates and only afterwards the process of division itself occurs. The biological meaning of these phenomena is not clear.Localization of RNA in the cells was performed on sections of ciliates B. truncatella, embedded in “Lowicryl K4M” at various stages: (1) before cell division (Figs. 2,3); (11) at the stage of macronucleus condensation; (111) during elongation of Ma (Fig.4); (1111) in young cells (0-5min. after division). For cytochemical labelling we used RNaseAcolloidal gold complexes (RNase-Au), which are known to bind to RNA containing cell ularstructures with high specificity. The influence of different parameters on the reliability and reproducibility of labelling was studied. In addition to the factors, discussed elsewhere, we found that the balance of mono- and bivalent cations is of great significance.


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