RESUMO
Gibberellic acid (GA3) is an important phytohormone, a member of gibberellins family, which acts as a promoter and regulator of plant growth. This study aimed to evaluate GA3 production by Fusarium moniliforme LPB03 and Gibberella fujikuroi LPB06 using different techniques of fermentation, solid state fermentation (SSF), submerged fermentation (SmF), and semisolid state fermentation (SSSF), and different types of bioreactors. In all techniques, citric pulp (CP), a subproduct obtained from the extraction of orange juice, was employed as the substrate/support. GA3 production by SSF reached 7.60 g kg-1 and 7.34 g kg-1 in Erlenmeyer flasks and column bioreactors, respectively. For SmF, the highest concentration of GA3 obtained was 236.00 mg L-1 in Erlenmeyer flasks, 273.00 mg L-1 in a 10 L stirred tank reactor (STR), and 203.00 mg L-1 in a 1.5 L bubble column reactor (BCR). SSSF was conducted with a CP suspension. In this case, GA3 concentration reached 331.00 mg L-1 in Erlenmeyer flasks and 208 mg L-1 in a BCR. The choice of the fermentation technique is undoubtedly linked to the characteristics and productivity of each process. The methods studied are inexpensive and were found to produce good proportions of GA3, making them suitable for several applications.
Assuntos
Ácido Cítrico/química , Fermentação , Giberelinas/biossíntese , Reguladores de Crescimento de Plantas/biossíntese , Reatores Biológicos , Fusarium/química , Fusarium/crescimento & desenvolvimento , Fusarium/metabolismo , Gibberella/química , Gibberella/genética , Gibberella/crescimento & desenvolvimento , Giberelinas/química , Giberelinas/genética , Reguladores de Crescimento de Plantas/química , Reguladores de Crescimento de Plantas/genéticaRESUMO
Fusarium tupiense, the main causal agent of mango malformation in Brazil, is described through a combination of morphological, biological and molecular markers. This new species belongs to the Gibberella fujikuroi species complex (GFSC) and has an anamorph morphologically similar to Fusarium mangiferae and F. sterilihyphosum. F. tupiense can be differentiated from other species in the G. fujikuroi species complex on the basis of sexual crosses, amplified fragment length polymorphism (AFLP) markers and partial sequences of the tef1 and tub2 genes. Female fertility for field isolates of F. tupiense appears to be low. PCR with primers specific for the mating type (MAT) alleles and sexual crosses identified this species as heterothallic with two idiomorphs. Female-fertile tester strains were developed for the identification of field strains of this species through sexual crosses.
Assuntos
Fusarium/classificação , Gibberella/classificação , Mangifera/microbiologia , Filogenia , Doenças das Plantas/microbiologia , Alelos , Análise do Polimorfismo de Comprimento de Fragmentos Amplificados , Brasil , Cruzamentos Genéticos , DNA Fúngico/genética , Fusarium/citologia , Fusarium/genética , Fusarium/isolamento & purificação , Genes Fúngicos Tipo Acasalamento/genética , Gibberella/citologia , Gibberella/genética , Gibberella/isolamento & purificação , Inflorescência/microbiologia , Brotos de Planta/microbiologia , Esporos Fúngicos/classificação , Esporos Fúngicos/citologia , Esporos Fúngicos/genética , Esporos Fúngicos/isolamento & purificaçãoRESUMO
Pineapple (Ananas comosus) is native to South America and widely planted as a fruit crop in the tropics and sub-tropics. This plant is susceptible to a number of fungal diseases of which the most severe is fusariosis. The disease is caused by Fusarium guttiforme and occurs only in South and Central America. The occurrence of a similar disease on pineapples in South Africa has prompted a re-evaluation of the Fusarium sp. associated with pineapple fruit rot. Phylogenetic relationships of isolates from pineapples collected in Brazil and South Africa were assessed based on sequence data for the translation elongation factor-1-α, histone H3 and ß-tubulin gene regions. Analyses showed that the South African isolates represent a species distinct from Brazilian isolates. The South African isolates are characterised by a concentration of aerial mycelium at the centres of the colonies, different to the Brazilian isolates that have an even distribution of aerial mycelium. Both phylogenetic and morphological data show that the disease on pineapple in South Africa is caused by a new Fusarium species described here as F. ananatum sp. nov.
Assuntos
Ananas/microbiologia , Fusarium/classificação , Gibberella/classificação , Doenças das Plantas/microbiologia , Brasil , Frutas/microbiologia , Proteínas Fúngicas/genética , Fusarium/genética , Fusarium/isolamento & purificação , Gibberella/genética , Gibberella/isolamento & purificação , Dados de Sequência Molecular , Fator 1 de Elongação de Peptídeos/genética , Filogenia , África do SulRESUMO
Several isolates of three Fusarium species associated with the Gibberella fujikuroi species complex were characterized for their ability to synthesize gibberellins (GAs): Fusarium sacchari (mating population B), Fusarium konzum (mating population I) and Fusarium subglutinans (mating population E). Of these, F. sacchari is phylogenetically related to Fusarium fujikuroi and is grouped in the Asian clade of the complex, while F. konzum and F. subglutinans are only distantly related to Fusarium fujikuroi and belong to the American clade. Variability was found between the different F. sacchari strains tested. Five isolates (B-12756; B-1732, B-7610, B-1721 and B-1797) were active in GA biosynthesis and accumulated GA(3) in the culture fluid (2.76-28.4 microg/mL), while two others (B-3828 and B-1725) were inactive. GA(3) levels in strain B-12756 increased by 2.9 times upon complementation with ggs2 and cps-ks genes from F. fujikuroi. Of six F. konzum isolates tested, three (I-10653; I-11616; I-11893) synthesized GAs, mainly GA(1), at a low level (less than 0.1 microg/mL). Non-producing F. konzum strains contained no GA oxidase activities as found for the two F. subglutinans strains tested. These results indicate that the ability to produce GAs is present in other species of the G. fujikuroi complex beside F. fujikuroi, but might differ significantly in different isolates of the same species.
Assuntos
Fusarium , Gibberella , Giberelinas/biossíntese , Oxigenases de Função Mista/metabolismo , Diterpenos do Tipo Caurano/biossíntese , Diterpenos do Tipo Caurano/química , Fusarium/química , Fusarium/enzimologia , Fusarium/genética , Fusarium/metabolismo , Gibberella/química , Gibberella/enzimologia , Gibberella/genética , Gibberella/metabolismo , Giberelinas/análise , Giberelinas/química , Estrutura Molecular , Especificidade da EspécieRESUMO
Gibberella zeae (anamorph Fusarium graminearum) causes Fusarium head blight of wheat. The authors used amplified fragment length polymorphisms (AFLPs) to characterize the genetic structure of two G. zeae populations from commercial wheat fields. The working hypothesis was that sufficient genetic exchange occurs between local populations to prevent significant partitioning of allelic variation. We analysed 216 AFLP loci for 113 isolates collected during the 2002 harvest season. All strains had AFLP profiles typical of G. zeae lineage 7. Both populations were genotypically diverse but genetically similar and potentially part of a larger, randomly mating population, with significant genetic exchange probably occurring between the two subpopulations. Linkage disequilibrium was low, but higher than reported for many other populations of G. zeae, and about 20% of the alleles detected were specific to one of the two subpopulations - results consistent with limited gene exchange between the two subpopulations. This study extends previous work with populations of G. zeae to include those found in Argentina, one of the world's largest wheat growing countries.
Assuntos
Análise do Polimorfismo de Comprimento de Fragmentos Amplificados/métodos , Fusarium/genética , Genes Fúngicos/genética , Gibberella/genética , Polimorfismo de Fragmento de Restrição/genética , Triticum/microbiologia , Argentina , Contaminação de Alimentos , Fusarium/isolamento & purificação , Frequência do Gene/genética , Variação Genética/genética , Gibberella/isolamento & purificação , Estatística como AssuntoRESUMO
The production of fumonisins, fusaproliferin and beauvericin by Gibberella fujikuroi different mating populations isolated from maize in Argentina was evaluated. From 203 strains of Fusarium verticillioides (G. fujikuroi mating population A), 193 were fumonisin producers. Among members of mating population A, female fertile strains produced 20% more toxin than female sterile ones. Among 78 Fusarium proliferatum strains (G. fujikuroi mating population D) 65 produced fumonisins. The percentage of strains that were high, intermediate and low level toxin producers varied according to the species evaluated and the area from which the strains were isolated. Fusarium subglutinans (G. fujikuroi mating population E) strains produced low levels or were no fumonisin producers. Strains from both G. fujikuroi mating populations D and E were able to produce fusaproliferin and beauvericin. Among the members of F. subglutinans (G. fujikuroi mating population E) the fusaproliferin production was more constant. Co-production of fumonisin, fusaproliferin and beauvericin among the strains belonging to G. fujikuroi D and E was also observed. The co-production of fumonisin, beauvericin and fusaproliferin in maize need to be considered, since from the toxicological point of view interactions between these toxins could occur. The toxigenic ability of the strains evaluated prompt us that is necessary to determine the natural occurrence of fusaproliferin and beauvericin in Argentinean maize.
Assuntos
Cruzamentos Genéticos , Depsipeptídeos , Gibberella/metabolismo , Micotoxinas/metabolismo , Argentina , Fumonisinas/metabolismo , Gibberella/genética , Gibberella/fisiologia , Peptídeos/metabolismo , Fenótipo , Terpenos/metabolismo , Zea mays/microbiologiaRESUMO
The steps involved in kaurenolide and fujenoic acids biosynthesis, from ent-kauradienoic acid and ent-6alpha,7alpha-dihydroxykaurenoic acid, respectively, are demonstrated in the gibberellin (GA)-deficient Gibberella fujikuroi mutant SG139, which lacks the entire GA-biosynthesis gene cluster, complemented with the P450-1 gene of GA biosynthesis (SG139-P450-1). ent-[2H]Kauradienoic acid was efficiently converted into 7beta-hydroxy[2H]kaurenolide and 7beta,18-dihydroxy[2H]kaurenolide by the cultures while 7beta-hydroxy[2H]kaurenolide was transformed into 7beta,18-dihydroxy[2H]kaurenolide. The limiting step was found to be hydroxylation at C-18. In addition, SG139-P450-1 transformed ent-6alpha,7alpha-dihydroxy[14C4]kaurenoic acid into [14C4]fujenoic acid and [14C4]fujenoic triacid. Fujenal was also converted into the same products but was demonstrated not to be an intermediate in this sequence. All the above reactions were absent in the mutant SG139 and were suppressed in the wild-type strain ACC917 by disruption of the P450-1 gene. Kaurenolide and fujenoic acids synthesis were associated with the microsomal fraction and showed an absolute requirement for NADPH or NADH, all properties of cytochrome P450 monooxygenases. Only 7beta-hydroxy[14C4]kaurenolide synthesis and not further 18-hydroxylation was detected in the microsomal fraction. The substrates for the P450-1 monooxygenase, ent-kaurenoic acid and [2H]GA12, efficiently inhibited kaurenolide synthesis with I50 values of 3 and 6 microM, respectively. Both substrates also inhibited ent-6alpha,7alpha-dihydroxy[14C4]kaurenoic acid metabolism by SG139-P450-1. Conversely, [14C4]GA14 synthesis from [14C4]GA12-aldehyde was inhibited by ent-[2H]kauradienoic acid and fujenal with I50 values of 10 and 30 microM, respectively. These results demonstrate that kaurenolides and seco-ring B kaurenoids are formed by the P450-1 monooxygenase (GA14 synthase) of G. fujikuroi and are thus side products that probably result from stabilization of radical intermediates involved in GA14 synthesis.
Assuntos
Aldeídos/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Diterpenos/metabolismo , Gibberella/enzimologia , Giberelinas/biossíntese , Aldeídos/química , Radioisótopos de Carbono , Inibidores das Enzimas do Citocromo P-450 , Sistema Enzimático do Citocromo P-450/genética , Diterpenos/química , Diterpenos/farmacologia , Inibidores Enzimáticos/metabolismo , Inibidores Enzimáticos/farmacologia , Flavina-Adenina Dinucleotídeo/metabolismo , Gibberella/genética , Gibberella/metabolismo , Isoenzimas , Microssomos/metabolismo , NADP/metabolismo , Especificidade por Substrato , Transformação GenéticaRESUMO
Recent studies have shown that the genes of the gibberellin (GA) biosynthesis pathway in the fungus Gibberella fujikuroi are organized in a cluster of at least seven genes. P450-1 is one of four cytochrome P450 monooxygenase genes in this cluster. Disruption of the P450-1 gene in the GA-producing wild-type strain IMI 58289 led to total loss of GA production. Analysis of the P450-1-disrupted mutants indicated that GA biosynthesis was blocked immediately after ent-kaurenoic acid. The function of the P450-1 gene product was investigated further by inserting the gene into mutants of G. fujikuroi that lack the entire GA gene cluster; the gene was highly expressed under GA production conditions in the absence of the other GA-biosynthesis genes. Cultures of transformants containing P450-1 converted ent-[(14)C]kaurenoic acid efficiently into [(14)C]GA(14), indicating that P450-1 catalyzes four sequential steps in the GA-biosynthetic pathway: 7beta-hydroxylation, contraction of ring B by oxidation at C-6, 3beta-hydroxylation, and oxidation at C-7. The GA precursors ent-7alpha-hydroxy[(14)C]kaurenoic acid, [(14)C]GA(12)-aldehyde, and [(14)C]GA(12) were also converted to [(14)C]GA(14). In addition, there is an indication that P450-1 may also be involved in the formation of the kaurenolides and fujenoic acids, which are by-products of GA biosynthesis in G. fujikuroi. Thus, P450-1 displays remarkable multifunctionality and may be responsible for the formation of 12 products.