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1.
Planta ; 251(2): 40, 2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31907631

RESUMO

MAIN CONCLUSION: A cytochrome P450 and a 2-oxoglutarate-dependent dioxygenase genes responsible, respectively, for the biosyntheses of canonical and non-canonical strigolactones in Lotus japonicus were identified by transcriptome profiling and mutant screening. Strigolactones (SLs) are a group of apocarotenoids with diverse structures that act as phytohormones and rhizosphere signals. The model legume Lotus japonicus produces both canonical and non-canonical SLs, 5-deoxystrigol (5DS) and lotuslactone (LL), respectively, through oxidation of a common intermediate carlactone by the cytochrome P450 (CYP) enzyme MAX1. However, the pathways downstream of MAX1 and the branching point in the biosyntheses of 5DS and LL have not been elucidated. Here, we identified a CYP and a 2-oxoglutarate-dependent dioxygenase (2OGD) genes responsible, respectively, for the formation of Lotus SLs by transcriptome profiling using RNA-seq and screening of SL-deficient mutants from the Lotus retrotransposon 1 (LORE1) insertion mutant resource. The CYP and 2OGD genes were named DSD and LLD, respectively, after 5DS or LL defective phenotype of the mutants. The involvements of the genes in Lotus SL biosyntheses were confirmed by restoration of the mutant phenotype using Agrobacterium rhizogenes-mediated transformation to generate transgenic roots expressing the coding sequence. The transcript levels of DSD and LLD in roots as well as the levels of 5DS and LL in root exudates were reduced by phosphate fertilization and gibberellin treatment. This study can provide the opportunity to investigate how and why plants produce the two classes of SLs.

2.
Curr Biol ; 29(18): 3041-3052.e4, 2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-31522940

RESUMO

Parasitic plants in the genus Striga, commonly known as witchweeds, cause major crop losses in sub-Saharan Africa and pose a threat to agriculture worldwide. An understanding of Striga parasite biology, which could lead to agricultural solutions, has been hampered by the lack of genome information. Here, we report the draft genome sequence of Striga asiatica with 34,577 predicted protein-coding genes, which reflects gene family contractions and expansions that are consistent with a three-phase model of parasitic plant genome evolution. Striga seeds germinate in response to host-derived strigolactones (SLs) and then develop a specialized penetration structure, the haustorium, to invade the host root. A family of SL receptors has undergone a striking expansion, suggesting a molecular basis for the evolution of broad host range among Striga spp. We found that genes involved in lateral root development in non-parasitic model species are coordinately induced during haustorium development in Striga, suggesting a pathway that was partly co-opted during the evolution of the haustorium. In addition, we found evidence for horizontal transfer of host genes as well as retrotransposons, indicating gene flow to S. asiatica from hosts. Our results provide valuable insights into the evolution of parasitism and a key resource for the future development of Striga control strategies.

4.
Pest Manag Sci ; 75(9): 2353-2359, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30843315

RESUMO

Strigolactones (SLs) are carotenoid-derived plant secondary metabolites that play important roles in various aspects of plant growth and development as plant hormones, and in rhizosphere communications with symbiotic microbes and also root parasitic weeds. Therefore, sophisticated regulation of the biosynthesis, perception and functions of SLs is expected to promote symbiosis of beneficial microbes including arbuscular mycorrhizal (AM) fungi and also to retard parasitism by devastating root parasitic weeds. We have developed SL mimics with different skeletons, SL biosynthesis inhibitors acting at different biosynthetic steps, SL perception inhibitors that covalently bind to the SL receptor D14, and SL function inhibitors that bind to the serine residue at the catalytic site. In greenhouse pot tests, TIS108, an azole-type SL biosynthesis inhibitor effectively reduced numbers of attached root parasites Orobanche minor and Striga hermonthica without affecting their host plants; tomato and rice, respectively. AM colonization resulted in weak but distinctly enhanced plant resistance to pathogens. SL mimics can be used to promote AM symbiosis and to reduce the application rate of systemic-acquired resistance inducers which are generally phytotoxic to horticultural crops. © 2019 Society of Chemical Industry.


Assuntos
Agricultura/métodos , Lactonas/metabolismo , Micorrizas/fisiologia , Raízes de Plantas/parasitologia , Plantas Daninhas/fisiologia , Controle de Plantas Daninhas , Simbiose
5.
Phytochemistry ; 157: 200-205, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30439621

RESUMO

Root exudates from Lotus japonicus were found to contain at least three different hyphal branching-inducing compounds for the arbuscular mycorrhizal (AM) fungus Gigaspora margarita, one of which had been previously identified as (+)-5-deoxystrigol (5DS), a canonical strigolactone (SL). One of the two remaining unknown hyphal branching inducers was purified and named lotuslactone. Its structure was determined as methyl (E)-2-(3-acetoxy-2-hydroxy-7-methyl-1-oxo-1,2,3,4,5,6-hexahydroazulen-2-yl)-3-(((R)-4-methyl-5-oxo-2,5-dihydrofuran-2-yl)oxy)acrylate, by 1D and 2D NMR spectroscopy, and HR-ESI- and EI-MS. Although lotuslactone, a non-canonical SL, contains the AB-ring and the enol ether-bridged D-ring, it lacks the C-ring and has a seven-membered cycloheptadiene in the A-ring part as in medicaol, a major SL of Medicago truncatula. Lotuslactone was much less active than 5DS, but showed comparable activity to methyl carlactonoate (MeCLA) in inducing hyphal branching of G. margarita. Other natural non-canonical SLs including avenaol, heliolactone, and zealactone (methyl zealactonoate) were also found to be moderate to weak inducers of hyphal branching in the AM fungus. Lotuslactone strongly elicited seed germination in Phelipanche ramosa and Orobanche minor, but Striga hermonthica seeds were 100-fold less sensitive to this stimulant.


Assuntos
Lactonas/química , Lotus/química , Lactonas/isolamento & purificação , Raízes de Plantas/química
6.
Nat Commun ; 9(1): 4680, 2018 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-30409967

RESUMO

Drought represents a major threat to food security. Mechanistic data describing plant responses to drought have been studied extensively and genes conferring drought resistance have been introduced into crop plants. However, plants with enhanced drought resistance usually display lower growth, highlighting the need for strategies to uncouple drought resistance from growth. Here, we show that overexpression of BRL3, a vascular-enriched member of the brassinosteroid receptor family, can confer drought stress tolerance in Arabidopsis. Whereas loss-of-function mutations in the ubiquitously expressed BRI1 receptor leads to drought resistance at the expense of growth, overexpression of BRL3 receptor confers drought tolerance without penalizing overall growth. Systematic analyses reveal that upon drought stress, increased BRL3 triggers the accumulation of osmoprotectant metabolites including proline and sugars. Transcriptomic analysis suggests that this results from differential expression of genes in the vascular tissues. Altogether, this data suggests that manipulating BRL3 expression could be used to engineer drought tolerant crops.


Assuntos
Arabidopsis/fisiologia , Secas , Desenvolvimento Vegetal , Feixe Vascular de Plantas/metabolismo , Receptores de Superfície Celular/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Metaboloma , Mutação/genética , Pressão Osmótica , Desenvolvimento Vegetal/genética , Raízes de Plantas/genética , Raízes de Plantas/fisiologia , Plantas Geneticamente Modificadas , Estresse Fisiológico/genética , Transcrição Genética , Tropismo
7.
J Exp Bot ; 69(9): 2231-2239, 2018 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-29522151

RESUMO

Strigolactones (SLs) can be classified into two structurally distinct groups: canonical and non-canonical SLs. Canonical SLs contain the ABCD ring system, and non-canonical SLs lack the A, B, or C ring but have the enol ether-D ring moiety, which is essential for biological activities. The simplest non-canonical SL is the SL biosynthetic intermediate carlactone. In plants, carlactone and its oxidized metabolites, such as carlactonoic acid and methyl carlactonoate, are present in root and shoot tissues. In some plant species, including black oat (Avena strigosa), sunflower (Helianthus annuus), and maize (Zea mays), non-canonical SLs in the root exudates are major germination stimulants. Various plant species, such as tomato (Solanum lycopersicum), Arabidopsis, and poplar (Populus spp.), release carlactonoic acid into the rhizosphere. These observations suggest that both canonical and non-canonical SLs act as host-recognition signals in the rhizosphere. In contrast, the limited distribution of canonical SLs in the plant kingdom, and the structure-specific and stereospecific transportation of canonical SLs from roots to shoots, suggest that plant hormones inhibiting shoot branching are not canonical SLs but, rather, are non-canonical SLs.


Assuntos
Germinação , Lactonas/química , Reguladores de Crescimento de Planta/química , Fenômenos Fisiológicos Vegetais , Plantas/química , Lactonas/metabolismo , Micorrizas/fisiologia , Reguladores de Crescimento de Planta/metabolismo , Brotos de Planta/crescimento & desenvolvimento , Plantas/metabolismo , Plantas/microbiologia
8.
New Phytol ; 218(4): 1522-1533, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29479714

RESUMO

Strigolactones (SLs) are a class of plant hormones which regulate shoot branching and function as host recognition signals for symbionts and parasites in the rhizosphere. However, steps in SL biosynthesis after carlactone (CL) formation remain elusive. This study elucidated the common and diverse functions of MAX1 homologs which catalyze CL oxidation. We have reported previously that ArabidopsisMAX1 converts CL to carlactonoic acid (CLA), whereas a rice MAX1 homolog has been shown to catalyze the conversion of CL to 4-deoxyorobanchol (4DO). To determine which reaction is conserved in the plant kingdom, we investigated the enzymatic function of MAX1 homologs in Arabidopsis, rice, maize, tomato, poplar and Selaginella moellendorffii. The conversion of CL to CLA was found to be a common reaction catalyzed by MAX1 homologs, and MAX1s can be classified into three types: A1-type, converting CL to CLA; A2-type, converting CL to 4DO via CLA; and A3-type, converting CL to CLA and 4DO to orobanchol. CLA was detected in root exudates from poplar and Selaginella, but not ubiquitously in other plants examined in this study, suggesting its role as a species-specific signal in the rhizosphere. This study provides new insights into the roles of MAX1 in endogenous and rhizosphere signaling.


Assuntos
Vias Biossintéticas , Lactonas/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Plantas/metabolismo , Homologia de Sequência de Aminoácidos , Arabidopsis , Biocatálise , Clonagem Molecular , Lactonas/química , Metaboloma , Microssomos/metabolismo , Filogenia , Reguladores de Crescimento de Planta/química , Raízes de Plantas/metabolismo , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/metabolismo , Tabaco/metabolismo
9.
Sci Rep ; 7(1): 8095, 2017 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-28808238

RESUMO

Seed priming is a commercially used technique for improving seed performance including germination. However, the treatment sometimes reduces seed longevity as a side effect, limiting the storable period or longevity of the seeds. To overcome this problem, molecular mechanisms involved in the loss of seed longevity during priming were analyzed using natural variations of Arabidopsis thaliana. We found that the Est-1 accession retained longevity for longer after priming compared to the reference accession Col-0. QTL analysis using 279 recombinant inbred lines (RILs) derived from the Est-1 × Col-0 detected three QTL regions associated with the loss of seed longevity during priming. Bulked transcriptome analysis (RNA-Seq with bulked RIL populations) revealed that genes related to brassinosteroid (BR) biosynthesis/signaling and cell wall modification were highly expressed in primed seeds with shorter longevity. After priming, BR-deficient mutants cyp85a1/a2 and det2 showed significantly longer longevity than the wild type (WT). Moreover, tetrazolium staining indicated that mutant seed coats were less permeable after priming than those of WT. We suggest that the loss of seed longevity in primed seed is due to increased seed coat permeability, which is positively regulated, at least partly, via BR signaling.


Assuntos
Arabidopsis/efeitos dos fármacos , Brassinosteroides/farmacologia , RNA de Plantas/genética , Sementes/efeitos dos fármacos , Arabidopsis/genética , Parede Celular/efeitos dos fármacos , Parede Celular/genética , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/genética , Germinação/efeitos dos fármacos , Germinação/genética , Locos de Características Quantitativas/efeitos dos fármacos , Locos de Características Quantitativas/genética , Sementes/genética , Transcriptoma/efeitos dos fármacos , Transcriptoma/genética
10.
Phytochemistry ; 136: 46-55, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28057327

RESUMO

Endogenous brassinosteroids (BRs) in non-flowering land plants were analyzed. BRs were found in a liverwort (Marchantia polymorpha), a moss (Physcomitrella patens), lycophytes (Selaginella moellendorffii and S. uncinata) and 13 fern species. A biologically active BR, castasterone (CS), was identified in most of these non-flowering plants but another biologically active BR, brassinolide, was not. It may be distinctive that levels of CS in non-flowering plants were orders of magnitude lower than those in flowering plants. 22-Hydroxycampesterol and its metabolites were identified in most of the non-flowering plants suggesting that the biosynthesis of BRs via 22-hydroxylation of campesterol occurs as in flowering plants. Phylogenetic analyses indicated that M. polymorpha, P. patens and S. moellendorffii have cytochrome P450s in the CYP85 clans which harbors BR biosynthesis enzymes, although the P450 profiles are simpler as compared with Arabidopsis and rice. Furthermore, these basal land plants were found to have multiple P450s in the CYP72 clan which harbors enzymes to catabolize BRs. These findings indicate that green plants were able to synthesize and inactivate BRs from the land-transition stage.


Assuntos
Brassinosteroides/isolamento & purificação , Cycadopsida/química , Arabidopsis/química , Brassinosteroides/química , Brassinosteroides/metabolismo , Briófitas/química , Bryopsida/química , Sistema Enzimático do Citocromo P-450/metabolismo , Gleiquênias/química , Hepatófitas/química , Marchantia/química , Oryza/química , Filogenia , Selaginellaceae/química , Esteroides Heterocíclicos
11.
J Pestic Sci ; 42(2): 58-61, 2017 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-30363140

RESUMO

One of the germination stimulants for root parasitic weeds produced by maize (Zea mays) was isolated and named methyl zealactonoate (1). Its structure was determined to be methyl (2E,3E)-4-((RS)-3,3-dimethyl-2-(3-methylbut-2-en-2-yl)-5-oxotetrahydrofuran-2-yl)-2-((((R)-4-methyl-5-oxo-2,5-dihydrofran-2-yl)oxy)methylene)but-3-enoate using by 1D and 2D NMR spectroscopy and ESI and EI-MS spectrometry. Feeding experiments with 13C-carlactone (CL), a biosynthetic intermediate for strigolactones, confirmed that 1 is produced from CL in maize. Methyl zealactonoate strongly elicits Striga hermonthica and Phelipanche ramosa seed germination, while Orobanche minor seeds are 100-fold less sensitive to this stimulant.

12.
Proc Natl Acad Sci U S A ; 113(22): 6301-6, 2016 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-27194725

RESUMO

Strigolactones are a group of plant compounds of diverse but related chemical structures. They have similar bioactivity across a broad range of plant species, act to optimize plant growth and development, and promote soil microbe interactions. Carlactone, a common precursor to strigolactones, is produced by conserved enzymes found in a number of diverse species. Versions of the MORE AXILLARY GROWTH1 (MAX1) cytochrome P450 from rice and Arabidopsis thaliana make specific subsets of strigolactones from carlactone. However, the diversity of natural strigolactones suggests that additional enzymes are involved and remain to be discovered. Here, we use an innovative method that has revealed a missing enzyme involved in strigolactone metabolism. By using a transcriptomics approach involving a range of treatments that modify strigolactone biosynthesis gene expression coupled with reverse genetics, we identified LATERAL BRANCHING OXIDOREDUCTASE (LBO), a gene encoding an oxidoreductase-like enzyme of the 2-oxoglutarate and Fe(II)-dependent dioxygenase superfamily. Arabidopsis lbo mutants exhibited increased shoot branching, but the lbo mutation did not enhance the max mutant phenotype. Grafting indicated that LBO is required for a graft-transmissible signal that, in turn, requires a product of MAX1. Mutant lbo backgrounds showed reduced responses to carlactone, the substrate of MAX1, and methyl carlactonoate (MeCLA), a product downstream of MAX1. Furthermore, lbo mutants contained increased amounts of these compounds, and the LBO protein specifically converts MeCLA to an unidentified strigolactone-like compound. Thus, LBO function may be important in the later steps of strigolactone biosynthesis to inhibit shoot branching in Arabidopsis and other seed plants.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Dioxigenases/metabolismo , Lactonas/metabolismo , Oxirredutases/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Brotos de Planta/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Dioxigenases/genética , Regulação da Expressão Gênica de Plantas , Ferro/metabolismo , Ácidos Cetoglutáricos/metabolismo , Oxirredutases/genética , Fenótipo , Filogenia , Brotos de Planta/genética , Brotos de Planta/crescimento & desenvolvimento , Transcriptoma
13.
J Hum Genet ; 61(9): 839-42, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27225848

RESUMO

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by oculocutaneous albinism, platelet dysfunction and ceroid deposition. We report suspected ocular albinism in two Japanese sisters, caused by mutations in the HPS6 (Hermansky-Pudlak syndrome 6) gene. Trio-based whole-exome sequencing (WES) identified novel compound heterozygous mutations in HPS6 (c.1898delC: mother origin and c.2038C>T: father origin) in the two sisters. To date, 10 associated mutations have been detected in HPS6. Although we detected no general manifestations, including platelet dysfunction, in the sisters, even in long-term follow-up, we established a diagnosis of HPS type 6 based on the HPS6 mutations and absence of dense bodies in the platelets, indicating that WES can identify cases of HPS type 6. To the best of our knowledge, this is the first report of HPS6 mutations in Japanese patients.


Assuntos
Albinismo Ocular/diagnóstico , Albinismo Ocular/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Mutação , Irmãos , Alelos , Pré-Escolar , Exoma , Feminino , Angiofluoresceinografia , Genes Recessivos , Genótipo , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Japão , Linhagem , Fenótipo , Tomografia de Coerência Óptica
14.
J Pestic Sci ; 41(2): 55-58, 2016 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-30363099

RESUMO

Strigolactones (SLs) are carotenoid-derived signaling molecules that mediate symbiotic and parasitic communications in the rhizosphere and plant hormones that regulate the growth and development of plants through crosstalk with other hormones. Natural SLs are classified into two groups based on the stereochemistry of the B-C ring junction. Rice and sorghum plants, both gramineous crops, produce orobanchol-type and strigol-type SLs, respectively, while tobacco plants produce both types. In the present study, we demonstrate that such species-specific phenomena in SL production also occur in the transport of exogenous SLs from roots to shoots. In rice plants, strigol-type SLs such as 5-deoxystrigol have been reported to actively inhibit tiller bud outgrowth, whereas root-applied strigol-type SLs could not be detected in shoots harvested 20 hr after treatment, indicating that metabolites of SLs or other signaling compounds downstream of SLs-but not SLs themselves-are the true inhibitors of tiller bud outgrowth.

15.
New Phytol ; 206(3): 983-9, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25754513

RESUMO

Strigolactones released from plant roots trigger both seed germination of parasitic weeds such as Striga spp. and hyphal branching of the symbionts arbuscular mycorrhizal (AM) fungi. Generally, strigolactone composition in exudates is quantitatively and qualitatively different among plants, which may be involved in susceptibility and host specificity in the parasite-plant interactions. We hypothesized that difference in strigolactone composition would have a significant impact on compatibility and host specificity/preference in AM symbiosis. Strigolactones in root exudates of Striga-susceptible (Pioneer 3253) and -resistant (KST 94) maize (Zea mays) cultivars were characterized by LC-MS/MS combined with germination assay using Striga hermonthica seeds. Levels of colonization and community compositions of AM fungi in the two cultivars were investigated in field and glasshouse experiments. 5-Deoxystrigol was exuded exclusively by the susceptible cultivar, while the resistant cultivar mainly exuded sorgomol. Despite the distinctive difference in strigolactone composition, the levels of AM colonization and the community compositions were not different between the cultivars. The present study demonstrated that the difference in strigolactone composition has no appreciable impact on AM symbiosis, at least in the two maize cultivars, and further suggests that the traits involved in Striga-resistance are not necessarily accompanied by reduction in compatibility to AM fungi.


Assuntos
Interações Hospedeiro-Parasita , Lactonas/metabolismo , Micorrizas/fisiologia , Striga/fisiologia , Zea mays/parasitologia , Especificidade de Hospedeiro , Lactonas/química , Lactonas/isolamento & purificação , Extratos Vegetais/química , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Raízes de Plantas/parasitologia , Simbiose , Zea mays/química , Zea mays/metabolismo
16.
Planta ; 241(3): 687-98, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25417194

RESUMO

MAIN CONCLUSION: Nitrogen and phosphorus fertilization in one side of split-root sorghum plants systemically reduced root contents of strigolactones in both sides of the split roots. Shoot-derived signals other than auxin appeared to be involved in this process. Strigolactones (SLs) are a novel class of plant hormones regulating both shoot and root architectures and suggested to be functioning downstream of auxin. The levels of SLs in plant tissues and root exudates are regulated by nutrients, especially phosphorus (P) and nitrogen (N); however, the underlying mechanism remains elusive. We examined the effects of N and P fertilization on root contents of two SLs, sorgomol and 5-deoxystrigol, in sorghum plants pre-incubated under N and P free conditions using a split-root system. N and P fertilization to one side of the split-root plants systemically reduced root contents of SLs in both sides of the split roots. The shoot N and P levels increased when one side of the split-root plants was fertilized, while N and P levels in the non-fertilized split roots were unaffected. N fertilization decreased shoot and root IAA (indole-3-acetic acid) levels, while P fertilization did not affect them. IAA applied to the shoot apices increased root contents of 5-deoxystrigol but not that of sorgomol only when the plants were grown under P free conditions. Shoot (leaf) removal dramatically decreased the root contents of SLs but did not affect root IAA levels, and IAA applied to the stumps of leaves could not restore root contents of SLs. Consequently, shoot-derived signals other than auxin are suggested to be involved in the regulation of SL production in roots.


Assuntos
Reguladores de Crescimento de Planta/metabolismo , Raízes de Plantas/metabolismo , Sorghum/metabolismo , Fertilizantes , Ácidos Indolacéticos , Ftalimidas
17.
Proc Natl Acad Sci U S A ; 111(50): 18084-9, 2014 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-25425668

RESUMO

Strigolactones (SLs) stimulate seed germination of root parasitic plants and induce hyphal branching of arbuscular mycorrhizal fungi in the rhizosphere. In addition, they have been classified as a new group of plant hormones essential for shoot branching inhibition. It has been demonstrated thus far that SLs are derived from carotenoid via a biosynthetic precursor carlactone (CL), which is produced by sequential reactions of DWARF27 (D27) enzyme and two carotenoid cleavage dioxygenases CCD7 and CCD8. We previously found an extreme accumulation of CL in the more axillary growth1 (max1) mutant of Arabidopsis, which exhibits increased lateral inflorescences due to SL deficiency, indicating that CL is a probable substrate for MAX1 (CYP711A1), a cytochrome P450 monooxygenase. To elucidate the enzymatic function of MAX1 in SL biosynthesis, we incubated CL with a recombinant MAX1 protein expressed in yeast microsomes. MAX1 catalyzed consecutive oxidations at C-19 of CL to convert the C-19 methyl group into carboxylic acid, 9-desmethyl-9-carboxy-CL [designated as carlactonoic acid (CLA)]. We also identified endogenous CLA and its methyl ester [methyl carlactonoate (MeCLA)] in Arabidopsis plants using LC-MS/MS. Although an exogenous application of either CLA or MeCLA suppressed the growth of lateral inflorescences of the max1 mutant, MeCLA, but not CLA, interacted with Arabidopsis thaliana DWARF14 (AtD14) protein, a putative SL receptor, as shown by differential scanning fluorimetry and hydrolysis activity tests. These results indicate that not only known SLs but also MeCLA are biologically active in inhibiting shoot branching in Arabidopsis.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Vias Biossintéticas/fisiologia , Ácidos Carboxílicos/metabolismo , Lactonas/metabolismo , Reguladores de Crescimento de Planta/biossíntese , Cromatografia Líquida , Clonagem Molecular , Escherichia coli , Ésteres/metabolismo , Vetores Genéticos/genética , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/crescimento & desenvolvimento , Espectrometria de Massas em Tandem , Leveduras
18.
Phytochemistry ; 104: 21-9, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24856112

RESUMO

In this study the relationship between blue light- and brassinosteroid-enhanced leaf lamina bending and unrolling in rice was investigated. Twenty-four hours (h) irradiation with white or blue light increased endogenous brassinosteroid levels, especially those of typhasterol and castasterone, in aerial tissues of rice seedlings. There was an accompanying up-regulation of transcript levels of CYP85A1/OsDWARF, encoding an enzyme catalyzing C-6 oxidation, after 6h under either white or blue light. These effects were not observed in seedlings placed under far-red or red light regimes. It was concluded that blue light up-regulates the levels of several cytochrome P450 enzymes including CYP85A1, thereby promoting the synthesis of castasterone, a biologically active brassinosteroid in rice. Based on these findings, it is considered that blue light-mediated rice leaf bending and unrolling are consequences of the enhanced biosynthesis of endogenous castasterone. In contrast to aerial tissues, brassinosteroid synthesis in roots appeared to be negatively regulated by white, blue and red light but positively controlled by far-red light.


Assuntos
Brassinosteroides/metabolismo , Colestanóis/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Luz , Oryza/efeitos da radiação , Brassinosteroides/química , Brassinosteroides/efeitos da radiação , Colestanóis/química , Colestanóis/efeitos da radiação , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Sistema Enzimático do Citocromo P-450/efeitos da radiação , Genes Reporter , Especificidade de Órgãos , Oryza/genética , Oryza/fisiologia , Fenótipo , Floema/genética , Floema/fisiologia , Floema/efeitos da radiação , Folhas de Planta/genética , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/efeitos da radiação , Raízes de Plantas/genética , Raízes de Plantas/fisiologia , Raízes de Plantas/efeitos da radiação , Plântula/genética , Plântula/fisiologia , Plântula/efeitos da radiação , Fatores de Tempo , Regulação para Cima
19.
Phytochemistry ; 103: 85-88, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24768285

RESUMO

Root exudates from the allelopathic plant, black oat (Avena strigosa Schreb.), were found to contain at least six different germination stimulants for root parasitic plants, but no known strigolactones (SLs). One of these germination stimulants was purified and named avenaol. Its HR-ESI-TOFMS analysis indicated that the molecular formula of avenaol is C20H24O7, and thus it contains an additional carbon compared with known C19-SLs. Its structure was determined as 5-((E)-(5-(3-hydroxy-1,5,5-trimethyl-2-oxobicyclo[4.1.0]heptan-7-yl)-2-oxodihydrofuran-3(2H)-ylidene)methoxy)-3-methylfuran-2(5H)-one, by 1D and 2D NMR spectroscopy, and ESI- and EI-MS spectrometry. Although avenaol contains the C-D moiety, the common structural feature for all known SLs, it lacks the B ring and has an additional carbon atom between the A and C rings. Avenaol is a potent germination stimulant of Phelipanche ramosa seeds, but only a weak stimulant for seeds of Striga hermonthica and Orobanche minor.


Assuntos
Germinação/efeitos dos fármacos , Lactonas/química , Lactonas/farmacologia , Exsudatos de Plantas/química , Raízes de Plantas/química , Poaceae/química , Orobanche/efeitos dos fármacos , Exsudatos de Plantas/farmacologia , Striga/efeitos dos fármacos
20.
Plant Cell Physiol ; 54(11): 1837-51, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24009336

RESUMO

Endogenous levels of bioactive gibberellins (GAs) are controlled by both biosynthetic and inactivation processes, and some cytochrome P450s are involved in this control mechanism. We have previously reported that CYP714B1 and CYP714B2 encode the enzyme GA 13-oxidase, which is required for GA1 biosynthesis, and that CYP714D1 encodes GA 16α,17-epoxidase, which inactivates the non-13-hydroxy GAs in rice. Arabidopsis has two CYP714 members, CYP714A1 and CYP714A2. To clarify the possible role of these genes in GA metabolism, enzymatic activities of their recombinant proteins were analyzed using a yeast expression system. We found that the recombinant CYP714A1 protein catalyzes the conversion of GA12 to 16-carboxylated GA12 (16-carboxy-16ß,17-dihydro GA12), a previously unidentified GA metabolite. Bioassays of this GA product showed that CYP714A1 is an inactivation enzyme in Arabidopsis. This was confirmed by the extreme GA-deficient dwarf phenotype shown by CYP714A1-overexpressing plants. Intriguingly, the recombinant CYP714A2 protein catalyzed the conversion of ent-kaurenoic acid into steviol (ent-13-hydroxy kaurenoic acid). When GA12 was used as a substrate for CYP714A2, 12α-hydroxy GA12 (GA111) was produced as a major product and 13-hydroxy GA12 (GA53) as a minor product. Transgenic Arabidopsis plants overexpressing the CYP714A2 gene showed semi-dwarfism. GA analysis showed that the levels of non-13-hydroxy GAs, including GA4, were decreased, whereas those of 13-hydroxy GAs, including GA1 (which is less active than GA4), were increased in the transgenic plants. Our results suggest that the CYP714 family proteins contribute to the production of diverse GA compounds through various oxidations of C and D rings in both monocots and eudicots.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Regulação da Expressão Gênica de Plantas , Giberelinas/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Vias Biossintéticas , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Germinação , Giberelinas/análise , Giberelinas/química , Modelos Biológicos , Mutação , Oxirredução , Fenótipo , Plantas Geneticamente Modificadas , Proteínas Recombinantes
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