Oryza Sativa Roots Research Articles

Inhibition effect of phenyl compounds from the Oryza sativa roots on melanin production in murine B16-F10 melanoma cells

Five phenyl compounds, vanillin (1), methyl trans-ferulate (2), trans-p-coumaric acid methyl ester (3), N-benzoyltryptamine (4), and N-(trans-cinnamoyl)tryptamine (5), were isolated from the roots of Oryza sativa L. and identified on the basis of spectroscopic data. Compounds 3 and 5 showed strong inhibition effect on melanin production in murine B16-F10 melanoma cells and tyrosinase activity. Also, the quantitative analysis of the compounds was carried out using LC/MS/MS experiment. Compounds 3 and 5 could be used as skin-whitening agents.

Upregulation of antioxidant enzymes by exogenous gallic acid contributes to the amelioration in Oryza sativa roots exposed to salt and osmotic stress.

The aim of this study is to elucidate the influence of the exogenous application of gallic acid (GLA) in alleviating the detrimental effects of salinity (NaCl), osmotic stress (polyethylene glycol; PEG), and their combination in Oryza sativa L. roots. To produce same osmotic potential (-0.5 MPa), 3-week-old rice seedlings were treated with 120 mM NaCl and/or 20 % PEG6000 with/without GLA (0.75 and 1.5 mM) treatments for 72 h. Both alone and combination of stresses decreased growth (RGR) and osmotic potential (Ψ Π). Moreover, stress caused a significant increase in proline (Pro) and hydrogen peroxide (H2O2) contents. Also, Pokkali and IR-28 had higher H2O2-scavenging enzyme activities including catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) activities in NaCl-treated roots. Only CAT activity was induced in both cultivars with PEG. Therefore, the enhanced levels of lipid peroxidation (thiobarbituric acid reactive substances (TBARS)) were more pronounced under PEG than NaCl. However, GLA significantly mitigated NaCl and/or PEG-induced stress injury. Under salinity, TBARS was lesser in GLA-applied rice that was associated with greater activities of superoxide dismutase (SOD), peroxidase (POX), and APX. GLA in the presence of PEG improved the activities of CAT and POX. According to these findings, GLA alleviated the damaging effects of NaCl and/or PEG (especially under NaCl) by improving the antioxidative system in rice. This is the first study elucidating the effects of GLA on tolerance to salinity, osmotic stress, and their combination in plants.

Sub-cellular distribution of two salt-induced peptides in roots of Oryza sativa L. var Nonabokra

Living systems respond to changing environment by changing gene expression. In addition to changes in the level of expression of existing proteins, some new proteins may be synthesized. Such proteins not only can serve as markers, but may also play important role in adjusting to that specific environment. Targeting of these proteins to specific location within or outside the cell may also yield important clues to their function. In such a pursuit, ten days old seedlings of a relatively salt tolerant rice variety grown on MS medium were treated with 2% sodium chloride for three days. Root were harvested, ground, and fractionated in to sub-cellular components. Microsomes were further fractionated into constituent membranes. Proteins from these fractions were analyzed by SDS-PAGE and/or two dimensional separations. Results show induction of two new polypeptides which were present in total protein extract and soluble fractions. All other fractions failed to reveal induction of any new peptide under experimental conditions used. Key words: 2-D electrophoresis, fractionation, salt induced proteins, sub-cellular localization.

Mucilaginibacter oryzae sp. nov., isolated from soil of a rice paddy

A Gram-negative-staining, non-spore-forming bacterium devoid of flagella, designated strain B9(T), was isolated from rice paddy soil associated with the roots of Oryza sativa collected from Jinju, South Korea. Cells were straight rods, were catalase- and oxidase-positive and were able to hydrolyse pectin, xylan and laminarin. Growth of strain B9(T) was observed between 15 and 35 degrees C (optimum 25-30 degrees C) and between pH 5.0 and 8.0 (optimum pH 6.5-7.5). Strain B9(T) contained menaquinone-7 (MK-7) as a major isoprenoid quinone and summed feature 3 (C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH), iso-C(15 : 0) and C(16 : 0) as major fatty acids. The G+C content of the genomic DNA was 44.4 mol%. Comparative 16S rRNA gene sequence analysis showed that strain B9(T) belonged to the genus Mucilaginibacter, a member of the family Sphingobacteriaceae, and was most closely related to Mucilaginibacter kameinonensis SCK(T) (95.9 % sequence similarity). On the basis of chemotaxonomic data and molecular properties, strain B9(T) represents a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter oryzae sp. nov. is proposed. The type strain is B9(T) (=KACC 12816(T) =DSM 19975(T)).

Nitric oxide alleviates arsenic toxicity by reducing oxidative damage in the roots of Oryza sativa (rice)

Nitric oxide (NO) is a bioactive gaseous, multifunctional molecule playing a central role and mediating a variety of physiological processes and responses to biotic and abiotic stresses including heavy metals. The present study investigated whether NO applied exogenously as sodium nitroprusside (SNP) has any protective role against arsenic (As) toxicity in Oryza sativa (rice). Treatment with 50 μM SNP (a NO donor) significantly ameliorated the As-induced (25 or 50 μM) decrease in root and coleoptile length of rice. Further, As-induced oxidative stress measured in terms of malondialdehyde (MDA), superoxide ion ( O 2 - ), root oxidizability and H 2O 2 content was lesser upon supplementation of NO. It indicated a reactive oxygen species (ROS) scavenging activity of NO. NO addition reversed (only partially) the As-induced increase in activities of antioxidant enzymes – superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, and catalase. The study concludes that exogenous NO provides resistance to rice against As-toxicity and has an ameliorating effect against As-induced stress.

RNAi knockdown of Oryza sativa root meander curling gene led to altered root development and coiling which were mediated by jasmonic acid signalling in rice

Jasmonic acid (JA) is a well-known defence hormone, but its biological function and mechanism in rice root development are less understood. Here, we describe a JA-induced putative receptor-like protein (OsRLK, AAL87185) functioning in root development in rice. RNA in situ hybridization revealed that the gene was expressed largely in roots, and a fusion protein showed its localization on the plasma membrane. The primary roots in RNAi transgenic rice plants meandered and curled more easily than wild-type (WT) roots under JA treatment. Thus, this gene was renamed Oryza sativa root meander curling (OsRMC). The transgenic primary roots were shorter, the number of adventitious roots increased and the number of lateral roots decreased as compared to the WT. As well, the second sheath was reduced in length. Growth of both primary roots and second sheaths was sensitive to JA treatment. No significant change of JA level appeared in the roots between the transgenic rice line and WT. Expression of RSOsPR10, involved in the JA signalling pathway, was induced in transgenic rice. Western blotting revealed OsRMC induced by JA. Our results suggest that OsRMC of the DUF26 subfamily involved in JA signal transduction mediates root development and negatively regulates root curling in rice.

Overexpression of OsRAA1 causes pleiotropic phenotypes in transgenic rice plants, including altered leaf, flower, and root development and root response to gravity.

There are very few root genes that have been described in rice as a monocotyledonous model plant so far. Here, the OsRAA1 (Oryza sativa Root Architecture Associated 1) gene has been characterized molecularly. OsRAA1 encodes a 12.0-kD protein that has 58% homology to the AtFPF1 (Flowering Promoting Factor 1) in Arabidopsis, which has not been reported as modulating root development yet. Data of in situ hybridization and OsRAA1::GUS transgenic plant showed that OsRAA1 expressed specifically in the apical meristem, the elongation zone of root tip, steles of the branch zone, and the young lateral root. Constitutive expression of OsRAA1 under the control of maize (Zea mays) ubiquitin promoter resulted in phenotypes of reduced growth of primary root, increased number of adventitious roots and helix primary root, and delayed gravitropic response of roots in seedlings of rice (Oryza sativa), which are similar to the phenotypes of the wild-type plant treated with auxin. With overexpression of OsRAA1, initiation and growth of adventitious root were more sensitive to treatment of auxin than those of the control plants, while their responses to 9-hydroxyfluorene-9-carboxylic acid in both transgenic line and wild type showed similar results. OsRAA1 constitutive expression also caused longer leaves and sterile florets at the last stage of plant development. Analysis of northern blot and GUS activity staining of OsRAA1::GUS transgenic plants demonstrated that the OsRAA1 expression was induced by auxin. At the same time, overexpression of OsRAA1 also caused endogenous indole-3-acetic acid to increase. These data suggested that OsRAA1 as a new gene functions in the development of rice root systems, which are mediated by auxin. A positive feedback regulation mechanism of OsRAA1 to indole-3-acetic acid metabolism may be involved in rice root development in nature.

Rice root properties for internal aeration and efficient nutrient acquisition in submerged soil.

• The characteristics of Oryza sativa roots required for internal aeration may conflict with those for efficient nutrient acquisition, particularly the surface area available for absorbing nutrients and the extent of oxygenation of the rhizosphere. • A model was developed for calculating the steady-state diffusion of O2 through a primary root and its laterals and the simultaneous consumption of O2 in respiration and loss to the soil. Results for a realistic set of parameter values were compared with available experimental data, and a sensitivity analysis given. • It was seen that a system of coarse, aerenchmymatous, primary roots with gas-impermeable walls conducting O2 to short, fine, gas-permeable laterals (i.e. the basic architecture of current rice genotypes) provided the greatest absorbing surface per unit aerated root mass. • With this architecture and typical rates of root respiration, rates of O2 loss to the soil can be sufficient to, for example, nitrify sufficient NH4 + to NO3 - to allow a plant to absorb half its N as NO3 - , as well as to oxidize toxins such as Fe2+ .

Decomposition of Plant Residue as Influenced by its Lignin and N Itrogen

To quantitatively investigate the influence of plant nitrogen and ligni n content on the residue carbon decomposition, CO 2_C was measured from an incu ba tion experiment with 19 plant residues plus soil under 25 ℃ and water conte nt of 400 g·kg -1 air dried soil over a 9_week period. The 19 residues were sam pled fro m different organs with 13 plants, including Glycine max, Vigna sesquipedalis, D ioscorea esculenta, Luffa cylindrical, Oryza sativa, Zea mays, Triticum aestivum , Saccharum officinarum, Festuca arundinacea, Acorus calamus, Trapa quadrispinos a, Pi ttosporum tobira and Firmiana simplex. Weight loss of these residues was a lso ob tained from a field burying experiment over a 23_week period by using litter bag method. Decomposition of plant residues during the early 3_week incubation period was fa st with a wide variation. Thereafter the decomposition decreased and the variati on among residues became gradually insignificant. Cumulative amount of CO 2_C r el eased over the 9_week incubation period was found to be different among the resi dues. Average of the cumulative CO 2_C emission for all 19 residues was 178.0 m g, ranging from 103.6 mg for Oryza sativa root to 256.2 mg for Pittosporum t obira leaf. Correlation analysis indicated that decomposition of the plant res idue was positively dependent on its initial nitrogen content and negatively dependent o n its initial lignin content as well as the ratio of lignin to nitrogen. A furth er investigation suggested that the decomposition can be quantitatively describe d by Y=B 0+B 1N+B 2L. Parameters B 0, B 1 and B 2 are regressi on coefficients. The N and L represent the initial contents of nitrogen and lignin for a given residue, respectively. The Y could be either the first_order decay rate (B 0=3.51 ×10 -2 , B 1=4.61×10 -4 , B 2=-1.53×10 -4 , R 2=0.812 ** , n=19), or the percentage of CO 2_C re leased over the 9_week period (B 0=100, B 1=0.974, B 2=-0.364, R 2= 0.828 ** , n=19), or the percentage of weight loss over the 23_week period in the field burying e xperiment (B 0=150, B 1=1.496, B 2=-0.572, R 2=0.799 ** , n=17) . In addition, a good agreement (R 2=0.863 ** ,n=17) existed between amounts of the CO 2_C released from the incubation and the weight loss from the field burying experiment. It is concluded that decomposition of the plant residue either expressed as CO 2_ C emission in the laboratory incubation or as weight loss in the field burying e xperiment was significantly dependent on its initial contents of nitrogen and li gnin. Residues with higher nitrogen decomposed fast, while those with higher lig nin content decomposed slowly. Difference in the decomposition for various plant residues can be well identified over a 9_week incubation under 25 ℃ and water content of 400 g·kg -1 air dried soil. A further conclusion is that approx imately 8 0% of the variability in the decomposition can be quantitatively expressed by a linear combination of the initial contents of nitrogen and lignin for a given re sidue. The result also suggests that fraction of the labile carbon for a given p lant reside could be estimated from weight loss in the field burying experiment over a 23_week period.

Induction of Oxidative Stress in Roots of Oryza sativa L. in Response to Salt Stress

With the imposition of salt stress (0.5 to 3 % NaCl or CaCl2) a decrease in germination rate and accumulation of proline was observed in the root tissue. Both NaCl and CaCl2 solutions induced an increase in the total peroxide content and lipid peroxidation and decrease in catalase, guaiacol peroxidase and superoxide dismutase activities in root tissues suggesting an oxidative stress in the salt sensitive rice cultivar.

Induction of Ltp (lipid transfer protein) and Pal (phenylalanine ammonia-lyase) gene expression in rice roots colonized by the arbuscular mycorrhizal fungus Glomus mosseae.

The expression of a lipid transfer protein (LTP) gene is regulated in Oryza sativa roots in response to colonization by the mycorrhizal fungus Glomus mosseae. Transcript levels increased when the fungus forms appressoria and penetrates the root epidermis and decreased at the onset of the intercellular colonization of the root cortex. The analysis of histochemical GUS staining in transgenic rice plants carrying the Ltp/Gus construct confirm the induction of LTP: gene associated with fungal appressoria formation and penetration area. The induction of Ltp gene expression coincided in time with a transient increase in the expression of a phenylalanine ammonia-lyase (PAL:) gene and a transient accumulation of salicylic acid (SA) in the mycorrhizal roots. The expression of LTP: and PAL: was induced in rice roots after treatment with SA and Pseudomonas syringae indicating that both genes could be implicated in the plant defence response. The exogenous application of SA to rice interacting with the mycorrhizal fungus did not affect appressoria formation but, instead, resulted in a transient delay of root mycorrhization. Nevertheless, although LTP: maintained a prolonged SA-induced expression level, mycorrhizal formation could still proceed.

66 Effect of gibberellin and ancymidol on growth, morphology and viscoelastic properties of cell walls in seminal roots of Oryza sativa

66 Effect of gibberellin and ancymidol on growth, morphology and viscoelastic properties of cell walls in seminal roots of Oryza sativa

Effect of gibberellin and ancymidol on growth, morphology and viscoelastic properties of cell walls in seminal roots of Oryza sativa.

Effect of gibberellin and ancymidol on growth, morphology and viscoelastic properties of cell walls in seminal roots of Oryza sativa.

Caloosia Parlona N. Sp. From Soil Around Roots of Rice and C. Brevicaudata N. Sp. (Nematoda: Hemicycliophoridae) From Soil Around Roots of Citrus From Orissa, India

Two new species of Caloosia are described and figured. C. parlona n. sp. collected from soil around roots of Oryza sativa L. is distinguished by 1st head annule 21 μm wide, directed forward and outward; 2nd, 23 μm wide, directed outward; b = 5.8-7.2; spear = 75-92 μm; and males with c = 5.1-5.9 and spicules 40-47 μm long. C. brevicaudata n. sp. found in soil around the roots of citrus has the shortest female tail of all the named species in the genus.