The genetic variation of rice cultivars provides a resource for further varietal improvement through breeding. Some rice varieties are sensitive to benzobicyclon (BBC), a β-triketone herbicide that ...inhibits 4-hydroxyphenylpyruvate dioxygenase (HPPD). Here we identify a rice gene,
(
), that confers resistance to BBC and other β-triketone herbicides. We show that
encodes an Fe(II)/2-oxoglutarate-dependent oxygenase that detoxifies β-triketone herbicides by catalyzing their hydroxylation. Genealogy analysis revealed that BBC-sensitive rice variants inherited a dysfunctional
allele from an
rice variety. Forced expression of
in
conferred resistance not only to BBC but also to four additional β-triketone herbicides.
may prove useful for breeding herbicide-resistant crops.
Gibberellin (GA) 20-oxidase (GA20ox) is a key enzyme that normally catalyzes the penultimate steps in GA biosynthesis. One of the GA20ox genes in rice (Oryza sativa L.), OsGA20ox2 (SD1), is well ...known as the 'Green Revolution gene', and loss-of function mutation in this locus causes semi-dwarfism. Another GA20ox gene, OsGA20ox1, has also been identified, but its contribution to plant stature has remained unclear because no suitable mutants have been available. We isolated a mutant, B142, tagged with a T-DNA containing three CaMV 35S promoters, which showed a tall, GA-overproduction phenotype. The final stature of the B142 mutant reflects internode overgrowth and is approximately twice that of its wild-type parent. This mutant responds to application of both GA3 and a GA biosynthesis inhibitor, indicating that it is a novel tall mutant of rice distinct from GA signaling mutants such as slr1. The integrated T-DNAs, which contain three CaMV 35S promoters, are located upstream of the OsGA20ox1 open reading frame (ORF) in the B142 mutant genome. Analysis of mRNA and the endogenous GAs reveal that biologically active GA level is increased by up-regulation of the OsGA20ox1 gene in B142. Introduction of OsGA20ox1 cDNA driven by 35S promoter into the wild type phenocopies the morphological characteristics of B142. These results indicate that the elongated phenotype of the B142 mutant is caused by up-regulation of the OsGA20ox1 gene. Moreover, the final stature of rice was reduced by specific suppression of the OsGA20ox1 gene expression. This result indicates that not only OsGA20ox2 but also OsGA20ox1 affects plant stature.
Bispyribac sodium (BS), a pyrimidinyl carboxy herbicide, is a well-known inhibitor of acetolactate synthase (ALS) activity. ALS is an enzyme in the biosynthetic pathway for branched-chain amino ...acids. A mutant form of rice ALS (OsmALS W548L/S627I) that confers resistance to BS can be used as an in vitro selection marker gene for plant transformation. Since indica and indica-derived cultivars are thought to have lower BS sensitivity than japonica rice, the application of BS as a selectable reagent for genetic transformation in indica and indica-derived cultivars is more challenging than for japonica cultivars. In this study, callus and seedlings of eight different rice cultivars (five indica-derived cultivars, two indica cultivars and one japonica cultivar) were tested for BS sensitivity. Our study indicates for the first time that callus shows a higher sensitivity to BS than seedlings in indica and indica-derived cultivars. We used BS with OsmALS W548L/S627I to select transformed calli, and transgenic rice plants from indica and indica-derived cultivars were successfully obtained.
We describe the purification, cDNA cloning, and characterization of a defensin, AFP1, in Brassica juncea, which shares 100% amino acid sequence identity with Raphanus sativus defensin (Rs-AFP1) and ...has a high antifungal activity against Magnaporthe oryzae. The recombinant AFP1 synthesized in Escherichia coli showed thermostability and antifungal activity against a broad spectrum of rice pathogenic fungi. The changes of a negative to positive charge at the surface of AFP1 derived by amino acid substitutions showed more enhanced antifungal activities than the wild-type AFP1.
Abstract Pathogen attack is a serious problem in rice, which is one of the most economically important crops worldwide. Plant genes with disease resistance have been extensively analyzed. ...Antimicrobial peptides from a variety of organisms are known to inhibit the growth of pathogens. Antimicrobial peptides are usually small, cationic, and amphipathic and have open-chain forms with disulfide bonds leading to rigid and compact structures. A gene family of plant defensins (AFP) is conserved in several plant species, including those of the Brassicaceae, and does not appear to be toxic to mammalian and plant cells. Rice plants do not contain these peptides. AFP1 homologs in 8 Brassicaceae vegetables have been identified, and their structural differences have been determined. AFP1 gene variants from Brassica oleracea and B, campestris conferred an effective resistance to both rice blast and bacterial leaf blight. The results of in vitro and in vivo analyses suggest that plant defensins have the potential to enhance broad-spectrum disease resistance in rice through genetic engineering. Modification of signal peptides and mature peptides could contribute to the improvement of broad disease resistance in crop plants, including rice.
The TEIL (Tobacco EIN3-Like) gene is a tobacco homologue of arabidopsis Ethylene Insensitive 3 (EIN3), and the gene product binds an 8 bp sequence in the tobacco PR1a promoter in a sequence specific ...manner. It was found here that accumulation of TEIL transcript was induced by wounding and preceded basic PR gene expression. To study the downstream signalling pathway of TEIL, TEIL was overexpressed under the control of the constitutive 35S promoter in tobacco plants. In 35S::TEIL lines, basic PR genes, which are wound-, jasmonate-, and ethylene-inducible, were expressed constitutively. Next, the conserved 781 bp sequence among tobacco EIN3-like (EIL) protein genes was introduced as an inverted-repeat (IR) into tobacco to suppress expression of these genes. In two independent IRTEIL lines, the TEIL transcript was not found and transcripts of other tobacco EILs, NtEIL3, and NtEIL5, were reduced. In IRTEIL plants, wound-, jasmonate-, and ACC-induced accumulation of basic PR gene transcripts was significantly inhibited. These results indicate that TEIL functions upstream of tobacco basic PR genes in wound signalling via not only ethylene but also jasmonate. In 35S::TEIL plants, the pistil length of the flower was longer with a slight protrusion of the stigma compared with the control. In IRTEIL plants, the length of the stamens was shorter than the control with significant protrusion of the stigma in the flower. These observations indicate the involvement of tobacco EILs in flower development.
Protoclonal variation of plant regeneration in rice Kawata, M. (National Inst. of Agrobiological Resources, Ibaraki (Japan)); Harada, S; Antonio, B ...
Plant cell, tissue and organ culture,
(1992), Letnik:
28, Številka:
1
Journal Article
Callus-specific rearranged DNA in rice (Oryza sativa L.) was isolated by in-gel reassociation procedure. Southern hybridization experiments revealed that some clones were amplified significantly in ...primary callus induced from scutellum tissue. Rapid amplification of these clones was observed within 2 days after plating seeds onto callus-induction medium containing 2,4-D. NAA gave no significant effect on DNA amplification event. Colony formation process from isolated protoplasts and plant regeneration process from callus showed clone-specific and process-specific fluctuation patterns of copy number. Sequence analysis of the clones suggested that most of the clones were originated from organelle DNA. Comparison of copy number fluctuation pattern of organelle functional genes with that of the clones suggested multiformity and/or construction-specific amplification of organelle DNA.
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