Hélio Almeida Burity

The complete genome sequence of Chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability

Chromobacterium violaceum is one of millions of species of free-living microorganisms that populate the soil and water in the extant areas of tropical biodiversity around the world. Its complete genome sequence reveals (i) extensive alternative pathways for energy generation, (ii) ≈500 ORFs for transport-related proteins, (iii) complex and extensive systems for stress adaptation and motility, and (iv) widespread utilization of quorum sensing for control of inducible systems, all of which underpin the versatility and adaptability of the organism. The genome also contains extensive but incomplete arrays of ORFs coding for proteins associated with mammalian pathogenicity, possibly involved in the occasional but often fatal cases of human C. violaceum infection. There is, in addition, a series of previously unknown but important enzymes and secondary metabolites including paraquat-inducible proteins, drug and heavy-metal-resistance proteins, multiple chitinases, and proteins for the detoxification of xenobiotics that may have biotechnological applications.

Alleviation of water stress effects in cowpea by Bradyrhizobium spp. inoculation

Experiments were carried out to investigate the effects of different degrees of water stress on cowpea in the presence and absence of Bradyrhizobium spp. inoculation and to evaluate physiological responses to stress. The soil used was Yellow Latosol, pH 6.3 and the crop used was cowpea (Vigna unguiculata (L.) Walp.) cv. ‘IPA 204’. Stress was applied continuously by the control of matric potential (ψm) through a porous cup. The lowered soil ψm had a direct effect on the N2 fixation, but the strains Bradyrhizobium introduced by inoculation in the cowpea plants were superior to the indigenous strain demonstrating the importance of inoculation in the stressed plants. At the more negative ψm plants inoculated with the strains EI 6 formed associations of greater symbiotic efficiency which helped the cowpea plants to withstand drought stress better than the strain BR 2001 and the uninoculated control. The leghaemoglobin concentration was not inhibited in the drought-stressed plants at ψm -70 kPa when inoculated with the strain EI 6, which confered a differential degree of drought resistance in plants. The ψw declined in the stressed plants reaching values of -1.0 MPa which was sufficient to cause disturbance in nodulation and biomass production.

Efetividade da inoculação com rizóbio e fungos micorrízicos arbusculares em mudas de sabiá submetidas a diferentes níveis de fósforo

In order to optimize Mimosa caesalpiniifolia Benth seedlings production, an experiment was carried out to evaluate the inoculation with both arbuscular mycorrhizal fungi (AMF) and Rhizobium. Treatments, arranged in a factorial scheme, consisted of presence or absence of Rhizobium, and of AMF (a mixture of Glomus etunicatum, Acaulospora morrowae and A. longula), with three P levels (equivalent to 0, 20 and 40 kg/ha of P2O5), applied as triple superphosphate. The P application, in the absence or in the presence of AMF inoculation, did not enhance plant development, while the seedlings which received the double inoculation presented significant values on growth, height, leaf area, nitrogenase activity and others analyzed parameters, regardless of the P level. Mimosa caesalpiniifolia nodulation was enhanced by the inoculation with AMF, since plants which received Rhizobium alone showed significantly lower nodulation values than the ones which received both inoculations. There was an increase of the mycorrhizal and a decrease of the esporulation in the presence of Rhizobium.

Fungos micorrízicos arbusculares em áreas de plantio de leucena e sábia no estado de Pernambuco

RESUMO n A ocorrŒncia de fungos micorrIzicos arbusculares (FMAs) foi investigada em AEreas cultivadas com leucena (Leucaena leucocephala L.) e sabiAE (Mimosa caesalpiniaefolia Benth), no Estado de Pernambuco. Amostras de solo foram coletadas em cinco estaAies experimentais da Empresa Pernambucana de Pesquisa AgropecuAEria (IPA), nas cidades de Arcoverde, com plantio de leucena (AL) e sabiAE (AS); Caruaru, com plantio de leucena (CL); e ItambO (IS), Sao Bento do Una (SBS) e Serra Talhada (STS), com plantio de sabiAE. O nœmero de esporos variou de 69 (STS) a 437/50 g de solo (CL) e a colonizaAao micorrIzica, de 11 (CL) a 64% (IS). Nas AEreas com plantio de leucena, a colonizaAao foi inferior a 15%, enquanto naquelas com cultivo de sAEbia houve variaAao de 36 a 64%. Foram observadas 24 espOcies de FMAs, pertencentes aos gŒneros: Acaulospora (6), Archaeospora (1), Entrophospora (1), Gigaspora (3), Glomus (6), Paraglomus (1) e Scutellospora (6). As AEreas CL e STS foram as que apresentaram maior nœmero de espOcies (14). Acaulospora scrobiculata, Archaeospora leptoticha e Glomus etunicatum foram encontradas em todas as AEreas. ABSTRACT n The occurrence of arbuscular mycorrhizal fungi (AMF) in plantations of Leucaena leucocephala L. (leucaena) and Mimosa caesalpiniaefolia Benth (sabia) in the State of Pernambuco was investigated. Soil samples were collected in five research centers of the Agricultural Research Institute of Pernambuco (IPA), in the cities of Arcoverde n plantation of leucaena (AL) and sabiAE (AS); Caruaru (CL) n leucaena plantation; ItambO (IS), Sao Bento do Una (SBS) and Serra Talhada (STS) n plantation of sabiAE. Mycorrhizal spores were extracted from soil, with the highest number (437/50g of soil) being found in the CL region and the lowest (69/50g of soil) in the STS region. The mycorrhizal colonization ranged from 11% (CL) to 64% (IS). The colonization was inferior to 15% in areas of leucaena plantation, however, in areas of sabiAE, it ranged from 36% to 64%. Twenty-four AMF species were identified in the genus: Acaulospora (6), Archaeospora (1), Entrophospora (1), Gigaspora (3), Glomus (6), Paraglomus (1) and Scutellospora (6). The highest species number was recorded in the CL and STS regions (14). Acaulospora scrobiculata, Archaeospora leptoticha and Glomus etunicatum were found in all regions.

WATER STRESS RESPONSE ON THE ENZYMATIC ACTIVITY IN COWPEA NODULES

A greenhouse experiment was carried out aiming to study the effect of water stress on metabolic activity of cowpea nodules at different plant development stages. Cowpea plants were grown in pots with yellow latosol soil under three different matric potentials treatments: -7.0 (control-S1), -70.0 (S2) and <-85.0 KPa (S3). The experimental design was randomized blocks with sub-divided plots, each plot containing a different degree of water stress, divided in sub-plots for the four different developmental stages: E1 (0-15), E2 (15-30), E3 (20-35) and E4 (30-45) days after emmergence. Water stress treatments were applied by monitoring soil water potential using a set of porous cups. The effect of water stress was most harmful to cowpea when it was applied at E2 than at other symbiotic process stages. Shoot/root ratio decreased from 2.61 to 2.14 when matric potential treatment was <-85.0 and -70.0 KPa respectively. There was a reduction in the glutamine synthetase activity and phosphoenolpyruvate carboxilase activity with increased stress, while glutamine synthase activity was the enzyme most sensitive to water stress. Glutamate dehydrogenase activity increased in more negative matric potential, indicating that this enzyme is sufficiently activitye under water stress.

Hospedeiros e ciclos sucessivos de multiplicação afetam a detecção de fungos micorrízicos arbusculares em áreas impactadas por mineração gesseira

RESUMO ‐ O objetivo deste trabalho foi verificar a influencia de diferentes plantas hospedeiras e de ciclos de multiplicacao em potes de cultura sobre a deteccao e avaliacao da diversidade de fungos micorrizicos arbusculares (FMA) no semiarido, em areas de caatinga preservadas e impactadas por mineracao de gesso no semiarido (Araripina, PE). Foram selecionadas quatro areas de coleta: AN - caatinga nativa preservada, AM - arredores da mina, AR-rejeito e AI - interface entre o deposito de rejeito e uma area de caatinga degradada pela mineracao, todas com solo do tipo Latossolo Amarelo, variando de franco-arenoso a argiloso, com pH de 5,7 a 7,5; 8 a 161 mg.dm -3 P e 0,23 a 79,8 mg.dm -3 Fe. Amostras foram retiradas desses solos para exame imediato e preparo de culturas-armadilha para FMA, utilizando-se como plantas hospedeiras amendoim ( Arachis hypogaea L.) e sorgo granifero (Sorghum bicolor (L.) Moench) cultivar IPA-7301011. Logo apos a coleta e depois de cada ciclo de multiplicacao na cultura-armadilha (tres ciclos de tres meses cada), foram avaliados em amostras de raizes e de solo rizosferico: colonizacao radicular, numero de esporos, diversidade e similaridade de especies de FMAs entre as areas. As plantas de amendoim apresentaram valores mais altos de colonizacao radicular (76,5 a 99,5%) que as de sorgo (21% a 73%). Maior producao de esporos ocorreu no 2o e no 3o ciclo de culturasarmadilha. Foram identificadas 25 especies de FMAs nas areas estudadas, onde se destacaram Glomus intraradices Schenck & Smith, Glomus mosseae Gerdemann & Trappe e Paraglomus occultum Morton & Redecker, pela alta densidade de esporos produzidos. As areas apresentaram indice de similaridade de especies de FMAs variando de 40 a 67%, com os maiores indices entre as areas impactadas.

Characterisation and identification of arbuscular mycorrhizal fungi species by PCR/RFLP analysis of the rDNA internal transcribed spacer (ITS)

The polymerase chain reaction coupled with restriction fragment length polymorphism analysis (PCR/RFLP) was applied to distinguish arbuscular mycorrhizal fungi (AMF) species from an impacted semiarid soil. The ITS1-5.8S-ITS2 region was amplified with the primers ITS1 and ITS4 and the products of amplification were digested with the restriction enzymes HinfI, MboI and AluI. The obtained banding pattern, except for the AluI, allowed the distinction at the molecular level of the AMF species:Paraglomus occultum, Glomus mosseae, Glomus intraradices andGlomus etunicatum. The results showed that this technique has a potential to be used as a marker to differentiate AMF species with high phylogenetic affinity.

Drought Stress Response in Enzymatic Activities of Cowpea Nodules

Summary The response to drought stress of several nodule enzymes in cowpea ( Vigna unguiculata (L.) Walp.) cv. IPA 204 at different stages of N 2 fixation development, as well as their changes during the period of stress recovery are described. Stress was applied continuously by the control of water potential through a porous cup. Stress applied during the P 2 stage (15–30 d) interfered most. The recovery in nodule metabolic activity at the P 1 stage (0–15 d) was higher than at other stages. There was a slight reduction in PEPC activity with increased stress. NADH-GOGAT activity was the enzyme most sensitive to drought stress and most closely associated with N 2 ase (ARA in closed systems). The coupling between GS and NADH-GOGAT activities was lost as drought stress progressed. GDH activity remained not only insensitive to the stress but its activity even increased, indicating that cowpea nodules maintain sufficient activity of some assimilatory enzymes under drought stress.

Water deficit stress effects on N2 fixation in cowpea inoculated with different Bradyrhizobium strains

The objectives of this experiment were to select strains of Bradyrhizobium sp. resistant to water stress, envisaging an increase in N2 fixation in cowpea (Vigna unguiculata [L.] Walp.), and to verify the plants adaptive physiological responses to water stress. The experiment was carried out in greenhouse conditions using random complete blocks subdivided into plots adjusted to soil water potential levels of −6.0, −75.0, and −85.0 kPa, and subplots containing strains of Bradyrhizobium sp. (SEMIA 6145, 6086, 6002 and NFB 700), with four blocks. The soil was a Yellow Latosol with pH 6.3. The crop used was cowpea cv. IPA 204. Stress was applied continuously beginning 15 d after planting, by the control of water potential through a porous cup. Various parameters were evaluated every 7 days, until final harvest at 45 d. There was significant interaction between Bradyrhizobium strains and water stress. At the more negative ψm, plants inoculated with the SEMIA 6145 had higher LHb concentration, ureide-N, ψw and ...

Fixação biológica de nitrogênio em pastagens com diferentes intensidades de corte

Arch. Zootec. 59: 21-30. 2010. Descargas 832 FIXAcaO BIOLoGICA DE NITROGeNIO EM PASTAGENS COM DIFERENTES INTENSIDADES DE CORTE* BIOLOGICAL NITROGEN FIXATION IN GRASSLAND WITH DIFFERENT CUTTING INTENSITIES Silva, L.L.G.G.1, Alves, G.C.2A, Ribeiro, J.R.A.2B, Urquiaga, S.2C, Souto, S.M.2D, Figueiredo, M.V.B.3 e Burity, H.A.4 1UFRRJ. Coordenacao da Area Verde. IPJBRJ. Rua Jardim Botânico, 1008. CEP 22470180. Rio de Janeiro RJ. llggalindo@yahoo.com.br 2UFRRJ. Embrapa. Agrobiologia. BR 465, km 47. CEP 23851970. Seropedica RJ. Brasil. Agabrielacalves@yahoo.com.br; Bjabetous@yahoo.com.br; Csegundo@cnpabembrapa.br; Dsmsoouto@cnpab.embrapa.br 3EPEAL. IPA. CP 699. CEP 57025050. Maceio, AL. Brasil. mbarreto@elogica.com.br 4Embrapa. IPA. CP 1022. CEP50761000. Recife, PE. Brasil. burity@ipa.br Palavras chave adicionais Brachiaria. Capim elefante. Bacterias diazo-troficas. Additional keywords Brachiaria. Elephant grass. Diazotrophic bacteria. Resumo O manejo correto numa pastagem e o uso da fixacao biologica de nitrogenio (FBN) ajudam a torna-la sustentavel. Foram realizados tres experimentos, cada um com uma especie de capim forrageiro na estacao experimental da Empresa Pernambucana de Pesquisa Agropecuaria em Itambe, na Zona da Mata de Pernambuco. Foram avaliadas a producao de materia seca, acumulo de nitrogenio e FBN das plantas sob varios regimes de corte. O delineamento experimental foi inteiramente casualizado com 5 repeticoes que foram usasadas. Para Brachiaria decumbens e B. humidicola foram usadas intensidades de corte 5, 15, 25 cm e 25 cm + 80 kg N ha-1, e para o Pennisetum purpureum, 5, 25, 50 cm e 50 cm + 80 kg N ha-1. Os periodos avaliados foram transicao seca/aguas e aguas em 2001. A FBN foi estimada pela abundância natural (d15N). Corte drastico (5 cm), no periodo de transicao seca/aguas, contribuiu para producao e acumulo de nitrogenio na B. decumbens, mas nao houve influencia significativa das intensidades de cortes na FBN nas tres pastagens e nas estacoes. Concluiu-se que a contribuicao da FBN variou com a estacao e que cortes altos nao teve influencia sobre o N acumulado, deste modo confirma-se que as tres gramineas sao tolerantes a cortes drasticos. Summary The correct management of pastures and the use of biological nitrogen fixation (BNF) therein should be sustainable. As part of an investigation into how best to use BNF in pastures three experiments were performed at the experimental station of Empresa Pernambucana de Pesquisa Agropecuaria, Itambe, Pernambuco. These experiments evaluated the production of dry matter and N accumulation and BNF under various cutting regimes. A random experimental design with 5 replications was used. For Brachiaria decumbens and B. humidicola the treatments consisted of cutting intensities of 5, 15 and 25 cm, and 25 cm + 80 kg N ha-1, and for Pennisetum purpureum cutting intensities 5, 25 and 50 cm and 50 cm + 80 kg N ha-1. The periods in which the pastures were evaluated were the transition of the dry/wet season and the wet season of 2001. Accumulation of N via BNF was estimated by the natural abundance (d15N) method. Drastic cutting (5 cm) in the dry/wet season transition resulted in high accumulation of dry matter and N in B. decumbens, but there was no effect of cutting intensity on BNF by any of the grasses in either of the seasons. The conclusion is that the BNF contribution varied with season, and that high cutting did not have any influence on N accumulation, thus confirming that the three pasture grasses are tolerant to drastic cutting.