Oryza Sativa Cv Research Articles

Root growth and proton efflux rates of rice seedlings in a greenhouse environment

Growth patterns and mean proton efflux rates (E H+) in roots of rice seedlings (Oryza sativa cv. IAC 47) grown under light conditions in a greenhouse environment were studied. Fifteen days after emergence, seedlings were transferred to pots containing 3.7 L of nutrient solution with 1.43 mmol NNH4+ L¹ as the sole source of nitrogen, to induce four sequential cycles of solution acidification, starting with a pH value of 5.3. Mean proton effluxes were computed based on growth periods of 48 h (from 0 to 192 h). E H+ values were estimated from values of relative root growth rates (RGR), expressed as root area (RA) or fresh mass (FM), and the linear coefficient of the regression of total free protons in nutrient solution (U H+) on RA or FM. Total free protons in the solution and the acidification gradients (deltaU H+/deltaMF) were better related to FM than to RA. Root growth rates were affected by photosynthetic irradiance and temperature fluctuations in the greenhouse, and were not clearly related to E H+ values. However, it was concluded that when a linear relation between U H+ and fresh root mass is found, E H+ estimates expressed by FM may be more reliable than when expressed by RA units.

Residual phytotoxic activity of pethoxamid in soil and its concentration in soil water under different soil moisture conditions

The relationship between the residual phytotoxic activity of pethoxamid (2‐chloro‐N‐[2‐ethoxyethyl]‐N‐[2‐methyl‐1‐phenyl‐1‐propenyl] acetamide) on rice (Oryza sativa cv. Kiyohatamochi) seedlings and its behavior in soil was investigated under different moisture conditions. The phytotoxic activity of pethoxamid on the shoot growth of rice seedlings in soil was higher in 80% soil moisture content than in 70% and 60% soil moisture contents. The phytotoxic activity in soil in 70% and 80% soil moisture conditions decreased with the increasing time after application, but the phytotoxic activity was slight in 50% soil moisture conditions at any given time after application. The residues of pethoxamid in soil water, the amount adsorbed on soil solid, and the amount in total soil was reduced with the time after application in a similar manner among these soil moisture conditions. The residual phytotoxic activity of pethoxamid on the shoot growth of rice seedlings in soil was more highly correlated with the concentration in soil water than with the amounts adsorbed on soil solid and in total soil. The partition coefficients between the amounts of pethoxamid adsorbed on soil solid and its concentration in soil water were similar among the soils with different moisture conditions at each day, and the partition coefficient increased with the time after application. These results suggested that the residual phytotoxic activity of pethoxamid in soil depends on the decreasing concentration of pethoxamid in soil water with time, except in low soil‐moisture conditions, which were insufficient for seedling growth.

Phytotoxic activity of pethoxamid in soil under different moisture conditions

The phytotoxic activity of soil‐applied pethoxamid [2‐chloro‐N‐(2‐ethoxyethyl)‐N‐(2‐methyl‐1‐phenyl‐1‐propanyl) acetamide], (TKC‐94), on the plant growth of rice (Oryza sativa cv. Kiyohatamochi) seedlings as an assay plant in soil was investigated under different soil moisture conditions. The phytotoxic activity of pethoxamid mixed with soil on the shoot and root growth of rice seedlings was uppermost under the highest soil moisture condition and it decreased with declining soil moisture content, while the inhibition was greater on the root growth than the shoot growth. The amount of pethoxamid adsorbed on soil solid and the concentration of pethoxamid in soil water from soil applied with this herbicide were not influenced by the soil moisture content. In addition, the phytotoxic activity on the growth of rice seedlings in sea sand culture applied with the soil water from the herbicide‐applied soil was not influenced by the soil moisture content. In the sea sand culture, the phytotoxic activity of pethoxamid was significantly reduced in negative water potential as the concentration of polyethylene glycol‐6000 added to the water increased. It is suggested that the phytotoxic activity of pethoxamid in the soil primarily depends on the concentration in soil water, but the phytotoxic activity was affected by soil moisture through the effect on absorption of this herbicide by rice seedlings.

High-resolution mapping, cloning and molecular characterization of the Pi-k h gene of rice, which confers resistance to Magnaporthe grisea

In order to understand the molecular mechanisms involved in the gene-for-gene type of pathogen resistance, high-resolution genetic and physical mapping of resistance loci is required to facilitate map-based cloning of resistance genes. Here, we report the molecular mapping and cloning of a dominant gene (Pi-k) present in the rice line Tetep, which is associated with resistance to rice blast disease caused by Magnaporthe grisea. This gene is effective against M. grisea populations prevalent in the Northwestern Himalayan region of India. Using 178 sequence tagged microsatellite, sequence-tagged site, expressed sequence tag and simple sequence repeat (SSR) markers to genotype a population of 208 F2 individuals, we mapped the Pi-k h gene between two SSR markers (TRS26 and TRS33) which are 0.7 and 0.5 cM away, respectively, and can be used in markerassisted-selection for blast-resistant rice cultivars. We used the markers to identify the homologous region in the genomic sequence of Oryza sativa cv. Nipponbare, and a physical map consisting of two overlapping bacterial artificial chromosome and P1 artificial chromosome clones was assembled, spanning a region of 143,537 bp on the long arm of chromosome 11. Using bioinformatic analyses, we then identified a candidate blast-resistance gene in the region, and cloned the homologous sequence from Tetep. The putative Pi-k gene cloned from Tetep is 1.5 kbp long with a single ORF, and belongs to the nucleotide binding site-leucine rich repeat class of disease resistance genes. Structural and expression analysis of the Pi-k gene revealed that its expression is pathogen inducible.

High-resolution mapping, cloning and molecular characterization of the Pi-k h gene of rice, which confers resistance to Magnaporthe grisea

In order to understand the molecular mechanisms involved in the gene-for-gene type of pathogen resistance, high-resolution genetic and physical mapping of resistance loci is required to facilitate map-based cloning of resistance genes. Here, we report the molecular mapping and cloning of a dominant gene (Pi-k ( h )) present in the rice line Tetep, which is associated with resistance to rice blast disease caused by Magnaporthe grisea. This gene is effective against M. grisea populations prevalent in the Northwestern Himalayan region of India. Using 178 sequence tagged microsatellite, sequence-tagged site, expressed sequence tag and simple sequence repeat (SSR) markers to genotype a population of 208 F(2) individuals, we mapped the Pi-k ( h ) gene between two SSR markers (TRS26 and TRS33) which are 0.7 and 0.5 cM away, respectively, and can be used in marker-assisted-selection for blast-resistant rice cultivars. We used the markers to identify the homologous region in the genomic sequence of Oryza sativa cv. Nipponbare, and a physical map consisting of two overlapping bacterial artificial chromosome and P1 artificial chromosome clones was assembled, spanning a region of 143,537 bp on the long arm of chromosome 11. Using bioinformatic analyses, we then identified a candidate blast-resistance gene in the region, and cloned the homologous sequence from Tetep. The putative Pi-k ( h ) gene cloned from Tetep is 1.5 kbp long with a single ORF, and belongs to the nucleotide binding site-leucine rich repeat class of disease resistance genes. Structural and expression analysis of the Pi-k ( h ) gene revealed that its expression is pathogen inducible.

Transgenic Rice Plants Expressing Human CYP1A1 Remediate the Triazine Herbicides Atrazine and Simazine

The human cytochrome P450 CYP1A1 gene was introduced into rice plants (Oryza sativa cv. Nipponbare). One-month-old CYP1A1 plants grown in soil clearly showed a healthy growth and tolerance to 8.8 microM atrazine and 50 microM simazine, but nontransgenic plants were completely killed by the herbicides. Although transgenic and nontransgenic plants metabolized the two herbicides into the same sets of compounds, CYP1A1 plants metabolized atrazine and simazine more rapidly than did control plants. In small-scale experiments, residual amounts of atrazine and simazine in the culture medium of CYP1A1 plants were 43.4 and 12.3% of those in control medium; those of nontransgenic Nipponbare were 68.3 and 57.2%, respectively. When cultivated in soil with 2.95 microM atrazine and 3.15 microM simazine for 25 days, CYP1A1 plants eliminated 1.3 times more atrazine and 1.4 times more simazine from the soil than did control plants. Thus, CYP1A1 rice plants make it possible to remove atrazine and simazine more rapidly from the culture medium and soil than can nontransgenic Nipponbare.

Endo-β-mannanase and β-mannosidase activities in rice grains during and following germination, and the influence of gibberellin and abscisic acid

Grains of indica rice (Oryza sativa cv. Peiza 67) exhibit an increase in endo-β-mannanase activity, mostly after the completion of germination. According to tissue blots, the initial increase occurs in association with the embryo, and possibly the scutellum, although the largest sustained increase in activity is in the peripheral regions of the endosperm. The aleurone layer, being the only living region of the endosperm, is presumably the site of synthesis and secretion of the enzyme into the non-living, starch-laden region. β-Mannosidase activity is low throughout germination and subsequent seedling growth, particularly in the endosperm regions. Its activity profile does not mimic that of endo-β-mannanase. In the intact grain, gibberellin (GA) causes a relatively small increase in endo-β-mannanase activity, while abscisic acid (ABA) causes a large decrease; this inhibition is overcome to a considerable extent when GA is supplied along with ABA. β-Mannosidase activity is little affected by either GA or ABA. Embryoless half-grains imbibed in water exhibit only a small increase in endo-β-mannanase activity with time of imbibition, showing the necessity for a stimulus from the embryo for this to occur. Incubating half-grains in the presence of GA results in a large increase in enzyme activity; ABA reduces the amount of activity compared to the water controls. GA is capable of reversing the inhibitory effect of ABA with respect to endo-β-mannanase activity. As in the intact grains, β-mannosidase activity in the half-grains is unaffected by either GA or ABA. It is concluded that the major site for the production of endo-β-mannanase activity is the aleurone layer, and this event is influenced by the presence of the embryo; in the absence of the latter, the increase in enzyme activity is stimulated by GA. β-Mannosidase activity is low throughout germination and post-germination, it is not influenced by GA and ABA, and thus its activity is not regulated in a coordinated manner with that of endo-β-mannanase.

Cytological and embryological studies of anther in rice (Oryza sativa) cv. 'Rocca'

The anther wall, microsporogenesis, pollen development and pollen germination of Oryza sativa cv. 'Rocca' were examined cytologically. The young anther wall consists of an epidermis, a single layered endothecium, a middle layer and a single-layered tapetum. In the secretory tapetum, normal mitosis was observed. Chromosome counts were done on tapetal and microspore mother cells at diakinesis and the results were 2n = 24. Meiosis, in most microspore mother cells was regular. Irregularities were observed in some of the cells, including, univalents, lagging chromosomes, broken down of nucleoli and abnormalities in cytokinesis. The percent of these irregularities varies between anthers. Microspore tetrads were isobilateral. Polarisation was seen within individual microspores and pollen grains. Pollen grains are shed at three-celled stage.

Rice: sulfide-induced barriers to root radial oxygen loss, Fe2+ and water uptake, and lateral root emergence.

Akagare and Akiochi are diseases of rice associated with sulfide toxicity. This study investigates the possibility that rice reacts to sulfide by producing impermeable barriers in roots. Root systems of rice, Oryza sativa cv. Norin 36, were subjected to short-term exposure to 0.174 mm sulfide (5.6 ppm) in stagnant solution. Root growth was monitored; root permeability was investigated in terms of polarographic determinations of oxygen efflux from fine laterals and the apices of adventitious roots, water uptake, anatomy and permeability to Fe2+ using potassium ferricyanide. Both types of root responded rapidly to the sulfide with immediate cessation of growth, decreased radial oxygen loss (ROL) to the rhizospheres and reduced water uptake. Profiles of ROL measured from apex to basal regions of adventitious roots indicated that more intense barriers to ROL than normal were formed around the apices. Absorption of Fe2+ appeared to be impeded in sulfide-treated roots. In adventitious roots, deposition of lipid material (suberisation) and thickenings of walls within the superficial cell layers were obvious within a week after lifting the treatment and could prevent the emergence of laterals and commonly result in their upward longitudinal growth within the cortex. Death of laterals sometimes occurred prior to emergence; emergent laterals eventually died. In adventitious roots, blockages formed within the vascular and aeration systems in response to the sulfide. In both adventitious and lateral roots, sulfide-induced cell wall suberization and thickening of the superficial layers were correlated with reduced permeability to O2, water and Fe2+. This study sheds light on some of the symptoms of diseases such as Akiochi. The results correlate with the authors' previous findings on the effects on roots of sulfide and lower organic acids in Phragmites and of acetic acid in rice.

A gibberellin-regulated calcineurin B in rice localizes to the tonoplast and is implicated in vacuole function.

Many developmental and environmental signals are transduced through changes in intracellular calcium concentrations, yet only a few calcium-binding proteins have been identified in plants. Calcineurin B-like (CBL) proteins are calcium-binding proteins that are thought to function as plant signal transduction elements. RNA profiling using a rice (Oryza sativa cv Nipponbare) oligonucleotide microarray was used to monitor gene expression in de-embryonated rice grains. This analysis showed that a putative rice CBL gene responded to gibberellic acid, but not abscisic acid, treatment. The CBL gene family in rice contains at least 10 genes and these have extensive similarity to the CBLs of Arabidopsis (Arabidopsis thaliana). In yeast (Saccharomyces cerevisiae) two-hybrid assays, rice CBLs interact with the kinase partners of Arabidopsis CBLs. Only one rice CBL gene, OsCBL2, is up-regulated by GA in the aleurone layer. A homolog with 91% sequence identity to OsCBL2 was cloned from barley (Hordeum vulgare cv Himalaya), and designated HvCBL2. We examined the localization and function of OsCBL2 and HvCBL2 in rice and barley aleurone because changes in cytosolic calcium have been implicated in the response of the aleurone cell to GA. Green fluorescent protein translational fusions of OsCBL2 and OsCBL3 were localized to the tonoplast of aleurone cell protein storage vacuoles and OsCBL4-green fluorescent protein was localized to the plasma membrane. Data from experiments using antisense expression of OsCBL2 and HvCBL2 are consistent with a role for OsCBL2 in promoting vacuolation of barley aleurone cells following treatment with GA.

Cloning and biochemical properties of CDPK gene OsCDPK14 from rice

A rice CDPK gene, OsCDPK14 (AY144497), was cloned from developing caryopses of rice (Oryza sativa cv. Zhonghua 15). Its cDNA sequence (1922 bp) contains an ORF encoding a 514 amino acids protein (56.7kD, pl 5.18). OsCDPK14 shows the typical structural features of the CDPK family, including a conserved catalytic Ser/Thr kinase domain, an autoinhibitory domain and a CaM-like domain with four putative Ca2+-binding EF hands. Subcellular targeting indicated that OsCDPK14 was located in the cytoplasm, probably due to the absence of myristoylation and palmitoylation motifs. OsCDPK14 was expressed in Escherichia coli and purified from bacterial extracts. The recombinant protein was shown to be a functional protein kinase using Syntide-2, a synthetic peptide. Kinase activity was shown to be Ca2+-dependent, and this activation was strongly enhanced by Mn2+ and inhibited by W7 in vitro. These results provide significant insights into the regulation and biochemical properties of OsCDPK14, suggesting OsCDPK14 may be a signal factor of cytoplasm in rice plant.

Nitrogen balance in a paddy field planted with whole crop rice (Oryza sativa cv. Kusahonami) during two rice-growing seasons

This paper focuses on N balance in a paddy field planted with whole crop rice (Oryza sativa cv. Kusahonami). The experiment was conducted with two treatments during two rice-growing seasons: one was fertilized with N (160 kg N ha−1; 16N plot) and the other unfertilized (0N plot); both plots were fertilized with P and K. The N input from precipitation was 15 and 12 kg N ha−1 in 2002 and 2003, respectively. The N input from irrigation water reached as much as 123 and 69 kg N ha−1 in 2002 and 2003, respectively. This was because irrigation water contained higher NO3− concentrations ranging from 4 to 8 mg N l−1. The N uptake by rice plants was the major output: 118 and 240 kg N ha−1 in the 0N and 16N plots in 2002 and 103 and 238 kg N ha−1 in 2003, respectively. N losses by leaching were 4.8–5.3 and 6.5–7.3 kg N ha−1 in 2002 and in 2003, respectively. Laboratory experiments were carried out to estimate the amounts of N2 fixation and denitrification. Amount of N2 fixation was 43 and 0 kg N ha−1 in the 0N and 16N plots, respectively. Denitrification potential was quite high in both the plots, and 90% of the N input through irrigation water was lost through denitrification. Collectively, the total N inputs were relatively large due to irrigation water contaminated with NO3−, but N outflow loading, expressed as leaching−(irrigation water + precipitation + fertilizer), showed large negative values, suggesting that the whole crop rice field might serve as a constructed wetland for decreasing N.

Transgenic Rice Containing Human CYP2B6 Detoxifies Various Classes of Herbicides

The human gene for CYP2B6, a cytochrome P450 monooxygenase that inactivates xenobiotic chemicals, was introduced into Oryza sativa cv. Nipponbare by Agrobacterium-mediated transformation. At germination, R(1) seeds of transgenic rice plants expressing CYP2B6 (CYP2B6 rice) showed a high tolerance to 5 microM metolachlor, a preemergence herbicide that is degraded by CYP2B6. Thin-layer chromatography after culture with (14)C-labeled metolachlor revealed that the amounts of residual metolachlor decreased in plant tissues and the medium of CYP2B6 rice faster than those of untransformed Nipponbare. CYP2B6 rice plants were able to grow in the presence of 13 out of 17 herbicides: five chloroacetamides and mefenacet, pyributicarb, amiprofos-methyl, trifluralin, pendimethalin, norflurazon, and chlorotoluron. These herbicides differ in their modes of action and chemical structures. Transgenic rice expressing a xenobiotic-degrading human CYP2B6, which has broad substrate specificity, should be good not only for developing herbicide tolerant rice but also for reducing the environmental impact of agrochemicals.

A New 2‐Arylbenzofuran with Antioxidant Activity from the Black Colored Rice (Oryza sativa L.) Bran.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Metabolic Profiling of Tryptophan-overproducing Rice Calli that Express a Feedback-insensitive α Subunit of Anthranilate Synthase

The profile of aromatic metabolites in calli was compared between wild-type rice (Oryza sativa cv. Nipponbare) and tryptophan-overproducing transgenic rice lines that express a gene (OASA1D) for a feedback-insensitive alpha subunit of anthranilate synthase. Metabolic profiling by high-performance liquid chromatography coupled with photodiode array detection of ultraviolet absorbance revealed a total of 71 peaks in both wild-type and transgenic calli. Only a limited effect on the pattern of major aromatic compounds was observed in tryptophan-accumulating transgenic rice lines, with the exception of an approximately 80-fold increase in the amount of tryptophan. Expression of OASA1D induced relatively small changes in several minor metabolites. One of the minor metabolites whose abundance was increased by OASA1D expression was purified and identified as a previously unknown indole-alkaloid glucoside. The levels of free and conjugated forms of indole-3-acetic acid (IAA), a plant hormone derived from the tryptophan biosynthetic pathway, were determined separately by liquid chromatography and tandem mass spectrometry (LC-MS/MS). The amounts of both free IAA and its conjugates were increased in the transgenic calli, suggesting that the activity of anthranilate synthase or the concentration of tryptophan (or both) is an important determinant of IAA biosynthesis.

Interactions between irrigated rice ( Oryza sativa) growth, nitrogen amendments and infection by Hirschmanniella oryzae (Nematoda, Tylenchida)

Nitrogen amendments are often used to alleviate damage to rice plants caused by plant-parasitic nematodes. The population development of the endoparasitic nematode Hirschmanniella oryzae was followed on irrigated rice ( Oryza sativa cv. indica IR-13240-108-2-2-3) cultivated in containers, each supplemented with one of three nitrogen amendments ( N 0 = 0, N 1 = 80 and N 2 = 160 kg ha −1) applied in the form of urea. The effects of nitrogen concentration on irrigated rice growth were determined with plants cultivated in soils either infested ( I 1) or uninfested ( I 0) with nematodes. Populations of H. oryzae continued to increase in both soil and roots throughout the crop cycle. Nitrogen was without effect on soil populations, but large root nematode population increases were observed with the N 1 nitrogen amendment. Interactions were observed between nematodes and nitrogen on the rice yield components, depending on the level of nitrogen applied. The average single grain weight was the main affected yield component; N 1 increased the weight of each grain, but this effect was largely reduced in the presence of H. oryzae. Even though nitrogen amendments were able to counterbalance the negative effects of H. oryzae, nitrogen applied at the N 1 level was not considered a sustainable alternative because it increased nematode populations. Root nematode populations with nitrogen applied at the N 2 level were similar to those observed with N 0. However, at the N 2 level, nitrogen induced spikelet sterility and the plant physiological disturbances caused by excessive in-soil nitrogen would prevent multiplication of H. oryzae root populations.

Phytotoxic activity of pethoxamid in soil under different moisture conditions

The phytotoxic activity of soil-applied pethoxamid [2-chloro-N-(2-ethoxyethyl)-N-(2-methyl-1-phenyl-1-propanyl) acetamide], (TKC-94), on the plant growth of rice (Oryza sativa cv. Kiyohatamochi) seedlings as an assay plant in soil was investigated under different soil moisture conditions. The phytotoxic activity of pethoxamid mixed with soil on the shoot and root growth of rice seedlings was uppermost under the highest soil moisture condition and it decreased with declining soil moisture content, while the inhibition was greater on the root growth than the shoot growth. The amount of pethoxamid adsorbed on soil solid and the concentration of pethoxamid in soil water from soil applied with this herbicide were not influenced by the soil moisture content. In addition, the phytotoxic activity on the growth of rice seedlings in sea sand culture applied with the soil water from the herbicide-applied soil was not influenced by the soil moisture content. In the sea sand culture, the phytotoxic activity of pethoxamid was significantly reduced in negative water potential as the concentration of polyethylene glycol-6000 added to the water increased. It is suggested that the phytotoxic activity of pethoxamid in the soil primarily depends on the concentration in soil water, but the phytotoxic activity was affected by soil moisture through the effect on absorption of this herbicide by rice seedlings.

Detrimental Effects of Lead Phytotoxicity on Growth, Yield, and Metabolism of Rice

To elucidate the deleterious effects of excessive lead (Pb) on rice (Oryza sativa) cv. Swarn Mansoori, plants were grown in refined sand in complete nutrient solution for 42 days. On the 43rd day, Pb nitrate was superimposed at 1 mM (to rice) for 104 days (till harvest). A set of plants in complete nutrient solution was maintained as control for the same period. Excess Pb reduced the dry weight pronouncedly at harvest (after 104 days of metal supply) when the grain yield also decreased. Lead accumulation reduced the concentrations of chlorophyll in leaves, carotene, sugars, phenols, nonprotein nitrogen, protein, iron, manganese, copper, zinc, Hill reaction activity, and peroxidase activity (one of the anti-oxidative enzymes), but increased the concentrations of sulphur, phosphorus, magnesium (early stage) protein nitrogen, and activity of catalase, acid phosphatase, and ribonuclease in leaves of rice. Except for slight growth depression and reduction in number and size of leaves, tillers and inflorescence, no other visible symptoms of excessive Pb could be seen before harvesting.

Resistência à penetração em latossolos: valor limitante à produtividade de arroz de sequeiro

Este trabalho objetivou avaliar o valor de resistência à penetração limitante à produtividade de arroz de sequeiro (Oryza sativa cv. IAC 165) no conteúdo de água retida, na tensão de 0,05 e 0,01 MPa. Foram utilizadas amostras de Latossolo Vermelho, textura média (LVd) e, Latossolo Vermelho, textura argilosa (LVef), coletadas na profundidade de 0,00-0,20m, passadas em peneira de 0,004m e compactados em camadas de 0,03m, em vasos de 0,20m de altura e 0,25m de diâmetro (0,00982m³). Os valores de resistência à penetração foram determinados com o penetrômetro de anel dinamométrico. Utilizou-se o delineamento inteiramente casualizado, em esquema fatorial 4 x 2, com três repetições. No conteúdo de água retida, na tensão de 0,01MPa, o valor de resistência do solo à penetração limitante à produtividade de grãos de arroz de sequeiro foi de 2,38 e 2,07MPa, respectivamente, para o LVd e LVef. No conteúdo de água retida na tensão de 0,05MPa foram obtidas maiores produções no menor valor de resistência à penetração. O arroz de sequeiro foi menos produtivo no conteúdo de água retida na tensão de 0,05MPa.

Enhanced herbicide cross-tolerance in transgenic rice plants co-expressing human CYP1A1, CYP2B6, and CYP2C19

We introduced an expression plasmid, pIKBACH, co-expressing the human cytochrome P450 genes CYP1A1, CYP2B6, and CYP2C19, into rice plants ( Oryza sativa cv. ‘Nipponbare’). The transgenic rice plants (pIKBACH rice) were screened by a combination of hygromycin resistance, PCR, and Western blot analysis. The pIKBACH rice plants expressed all three P450 species and exhibited tolerance towards various herbicides with different chemical structures and different modes of action, including a photosynthesis inhibitor (chlortoluron), very long-chain fatty acids (VLCFAs) inhibitors (acetochlor, metolachlor, and thenylchlor), a carotenoid biosynthesis inhibitor (norflurazon), and a root-elongation inhibitor (pyributicarb). In addition, the pIKBACH rice plants showed high tolerance to two mixtures of three herbicides [quizalofop-ethyl (0.15 μM), metolachlor (2 μM), and norflurazon (0.4 μM); and mefenacet (2.5 μM), thenylchlor (2 μM), and pyributicarb (1.5 μM)]. Thin-layer chromatography analysis revealed that the pIKBACH transgenic rice plants exhibited high metabolic activity towards chlortoluron, metolachlor, and norflurazon. The metabolism of herbicides by the pIKBACH rice plants was enhanced additively by the introduced P450 species. Assuming that public and commercial acceptance is forthcoming, pIKBACH rice plants may become useful tools for the breeding of herbicide-tolerant crops and for phytoremediation of environmental pollution by organic chemicals.