The Apical Structure of Crown Roots in Rice Plants

Kawata, Shin-ichiro; Nishimaki, K.; Yamazaki, Koou

doi:10.1626/jcs.46.393

Cited by 8 publications

(9 citation statements)

References 4 publications

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“…The basal ends of these layers should correspond to the initial cells of these tissues (Figure 3c). This prediction corresponds to the previous observation of the divisional pattern of cells in the RAM (Kawata et al ., 1977). In their observation, the initial cells for epidermis, cortex, endodermis, and root cap surround the central cells of the RAM.…”

Section: Resultssupporting

confidence: 92%

Isolation and characterization of a rice WUSCHEL‐type homeobox gene that is specifically expressed in the central cells of a quiescent center in the root apical meristem

et al. 2003

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SummaryThe Arabidopsis WUSCHEL (WUS) protein, which plays an important role in the speci®cation of the stem cells in the shoot apical meristem (SAM), contains an`atypical' homeodomain (HD) with extra residues in its loop and turn regions. We speculated that a WUS-type atypical HD protein might also be involved in the speci®cation and maintenance of the root apical meristem (RAM) stem cells of rice. To investigate this possibility, we isolated and characterized a rice WUS-type homeobox gene designated quiescent-centerspeci®c homeobox (QHB ) gene. Using transformants carrying the QHB promoter-GUS and in situ hybridization, we found that QHB was speci®cally expressed in the central cells of a quiescent center (QC) of the root. During embryogenesis and crown root formation, QHB expression was observed prior to the morphological differentiation of the root. However, we detected different QHB expression patterns in the process of the RAM development, speci®cally between radicle and crown root formation, suggesting that the cell-fate determination of the QC may be controlled by different mechanisms. We also produced transformants that overexpress QHB or Arabidopsis WUS. These transformants did not form crown roots, but developed multiple shoots from ectopic SAMs with malformed leaves. On the basis of these observations, we propose that the WUS-type homeobox gene is involved in the speci®cation and maintenance of the stem cells (QC cells) in the RAM, by a mechanism similar to that for WUS in the SAM.

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Section: Resultssupporting

confidence: 92%

Isolation and characterization of a rice WUSCHEL‐type homeobox gene that is specifically expressed in the central cells of a quiescent center in the root apical meristem

et al. 2003

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“…The root cap is made up of columella and peripheral root cap cells that arise from a group of initial cells [57]. The columella cells are produced through periclinal divisions of columella initials (Fig.…”

Section: Peripheral Root Cap and Columella Initial Cells (Calyptrogens)mentioning

confidence: 99%

Molecular Genetics of Rice Root Development

Rebouillat¹,

Diévart²,

Verdeil³

et al. 2008

Rice

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Plant roots have a large range of functions, including acquisition of water and nutrients, as well as structural support. Dissecting the genetic and molecular mechanisms controlling rice root development is critical for the development of new rice ideotypes that are better adapted to adverse conditions and for the production of sustainably achieved rice yield potential. Most knowledge regarding the gene networks involved in root development has been accumulated in the model dicotyledon plant species Arabidopsis thaliana. Rice, the model monocotyledon species, presents several singularities compared to A. thaliana, including a root architecture characterized by a fibrous root system comprising five types of embryonic and postembryonic roots. The anatomy and morphology of the rice root system, which is typical for a cereal, differs from that of A. thaliana, for instance, by the presence of a lysigenous cortex and additional cell layers compared to the dicotyledon model. Moreover, the structure and functions of the root apical meristem (RAM) of rice are distinct from those of A. thaliana. Recently, several rice root mutants have been identified via forward or reverse genetics, and these will aid in forming hypothesis to characterize either the divergence or conservation of genetic pathways relative to A. thaliana. Furthermore, these mutants will help to identify key genes in rice roots that may be missing in A. thaliana. This review summarizes both classical and recent data concerning the molecular genetics of rice root development, including root anatomy and morphology, RAM structure, RAM patterning, and root mutants.

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“…Periclinal division, in particular, occurs frequently in the central region of the RC, and is believed to give rise to columella. The cells along the periphery of columella cells are sometimes referred to as the rhombic meristem (Kawata et al, 1977), whose mechanism has not been clarifi ed to date. (3) Root growth and the RC In the center of the root apical meristem there is a group of cells called the quiescent center, which does not divide as fast as the cells of the rest of the meristem.…”

Section: Formation and Renewal Of The Rc (1) Structure And Formation mentioning

confidence: 99%

“…The diameter of axile roots is subject to variation, and the diameter of the root apex also changes over the course of growth. However, there is a close interrelation between the diameter of the rice root apex and the size of the individual regions of the RC (Kawata et al, 1977). Thus, the structure of the RC of the axile roots more or less remains the same throughout the lifespan of the plant, even though there may be variations in the size of the RC.…”

Section: Formation and Renewal Of The Rc (1) Structure And Formation mentioning

confidence: 99%