http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/4373 Wed, 17 Sep 2025 01:29:58 GMT 2025-09-17T01:29:58Z http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/9418 Título: Seleção de espécies de Bacillus para o controle biológico do oídio da videira Autor: SANTOS, John Lennon Ferreira dos Primeiro orientador: LARANJEIRA, Delson Abstract: Powdery mildew caused by Erysiphe (Uncinula) necator (Schw.) Burr. is one of the primary diseases of the grapevine (Vitis vinifera L.), and its control is mainly based on the use of synthetic fungicides. However, ecologically friendly control strategies with low risk of food contamination, such as biocontrol agents, have been employed. The objectives of this work were: 1. To evaluate and identify Bacillus isolates antagonistic to E. necator; 2. Characterize the adaptation of the antagonist isolates' to environmental and nutritional stress conditions; 3. Characterize the mechanisms of action of Bacillus isolates antagonistic to E. necator; 4. Evaluate the application of antagonist isolates in the integrated management of grape powdery mildew. In an initial screening using 45 Bacillus spp. from the Embrapa Semi-Arid Microorganism Collection, six isolates showed a reduction in disease symptoms greater than 70.0% on detached leaves. Two experiments in a greenhouse demonstrated that, when applied weekly, the isolates LCB03, LCB28, and LCB30 showed control efficiency greater than 80%. Sequencing of 16s rDNA showed that LCB03 showed 100.0% homology with B. velezensis, LCB28 99.93% with B. tequillensis, and LCB30 99.4% with B. siamensis. The isolates showed minor differences in the requirement of carbon sources, ideal pH range, glucose concentrations, and different nitrogen sources for their growth in culture medium and metabolized nitrate and ammonium as nitrogen sources. In an in vitro assay, LCB28 and LCB30 significantly inhibited conidial germination in co-culture and by producing volatile organic compounds. The potential to synthesize antifungal cyclopeptide was confirmed by PCR-based detection of gene markers for surfactin, bacillomycin, fengycin, and bacillysin production in the LCB28 genome, and the markers for all these compounds plus iturin in the LCB30 genome. Weekly alternating application of triflumizol and difenoconazole with the isolates LCB28 and LCB30 in a greenhouse reduced the incidence of powdery mildew by more than 70% and the severity by more than 90% on average in a greenhouse experiment. Two field experiments showed that powdery mildew incidence and severity were significantly reduced by applying formulations containing LCB28 or LCB30 in an integrated management strategy that replaced the concentration of synthetic fungicides, except during concentration and initial fruit growth, which are highly susceptible phases. The results of the experiments indicate that LCB28 and LCB30 have great potential to be applied in integrated powdery mildew management programs in grapevines. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Tese Fri, 28 Jul 2023 00:00:00 GMT http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/9418 2023-07-28T00:00:00Z http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/9417 Título: Mancha de Stemphylium: etiologia, gama de hospedeiras e identificação de novas fontes de resistência em Capsicum e tomateiro Autor: TORRES, Tiago Bezerra Primeiro orientador: REIS, Ailton Abstract: The family Solanaceae includes many species of agricultural importance such as tomato (Solanum lycopersicum L.) and peppers and sweet peppers (Capsicum spp.), which are widely used as vegetables around the world. However, these plants might be affected by a series of pathogens inducing severe direct and indirect losses. Stemphylium leaf spot deserves special attention, especially in tomatoes, since the disease can reduce crop yield and quality. Symptoms occur on both leaf sides and consist of small dark spots, which enlarge and become grayish brown, compromising the photosynthetic surface. In tomato, the disease is caused by a complex of at least three species of Stemphylium: S. solani, S. lycopersici (= S. floridanum) and S. botryosum. In the genus Capsicum, the disease is caused by three Stemphylium species: S. solani, S. lycopersici, and S. vesicarium. In this context, the objectives of the present work were: (1) To generate information related to the etiology and the host range of the causal agent of Stemphylium leaf spot in Brazil; (2) To identify new sources of resistance in Solanum (Lycopersicon) and Capsicum germplasm and (3) to carry out an inheritance study with a new source of genetic resistance to S. lycopersici in an accession of the wild species S. habrochaites. Phylogenetic analyzes of the ITS-5.8S rDNA and glyceraldehyde-3-phosphate dehydrogenase (gapdh) genomic regions of 89 Stemphylium isolates obtained in species of the Solanaceae family. The isolates were placed in two distinct groups with either S. lycopersici or S. solani. Isolates of S. lycopersici (n=81) were detected in tomato, potato, eggplant, S. paniculatum, and Physalis angulata. Isolates of S. solani (n=8) were detected in S. aethiopicum var. gilo and tomato. The reaction of accessions from 18 plant species was evaluated for two S. lycopersici isolates with 12 of them displaying a susceptible reaction. In search of alternative sources of resistance, 40 accessions of Solanum (Lycopersicon) were inoculated with one S. lycopersici isolate. Twenty-seven accessions were detected with high levels of resistance in the species S. habrochaites (13), S. peruvianum (13) and S. pimpinellifolium (1). Solanum habrochaites ‘PI-127827’ was detected as a new source of resistance to S. lycopersici. A subgroup of resistant accessions showed molecular markers distinct from the Sm locus, indicating potential new resistance genes/alleles. The susceptible cultivar S. lycopersicum ‘Ponderosa’ was used as a female parent in interspecific crosses with ‘PI-127827’. The chi-square test in the F2 generation showed a good fit with a segregation pattern 9 (resistant): 7 (susceptible), indicating a genetic model of resistance under the control of two dominant, independent, and complementary genes. The reactions of the 37 Capsicum accessions were characterized based on epidemiological parameters. The accessions C. annuum ‘Jalapeño TS’ and C. annuum var. glabriusculum ‘CNPH–3839’ showed an immunity-like reaction against two S. lycopersici isolates. In conclusion, new and relevant information was generated that could contribute to the cultural and genetic management of Stemphylium spot in Brazil. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Tese Mon, 29 May 2023 00:00:00 GMT http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/9417 2023-05-29T00:00:00Z http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/9416 Título: Estudo da nematofauna em fragmentos de Mata Atlântica, Caatinga e em área produtora de coco do Estado de Pernambuco Autor: DAVID, Mariana Ferreira de Lima Primeiro orientador: GUIMARÃES, Lilian Margarete Paes Abstract: In the State of Pernambuco, there are the Caatinga and Atlantic Forest biomes. The Atlantic Forest has been diminished since the beginning of European colonization for the implantation of sugarcane plantations. The Caatinga biome is considered one of the most threatened ecosystems in Brazil. In Petrolina-PE, 35% of the areas of the Caatinga are reverted to agriculture and livestock, such as coconut production. The nematodes that occur in coconut producing areas are responsible for reducing the productive potential. In addition to the parasitic action, nematodes can be used as bioindicators of soil quality, as they are sensitive to edaphic disturbances. Thus, the study aimed to characterize the nematofauna and the physical and chemical attributes of the soil in the Atlantic Forest and Caatinga fragments, as well as to characterize the nematofauna and the physical and chemical attributes of the soil in a coconut producing area in Petrolina. Soil samples were randomly collected, 10 m apart from each other. After collection, the simple samples were separated for physical-chemical and nematological analyses. The physical and chemical analyzes were based on soil moisture, particle density, soil density, total porosity, pH, soil electrical conductivity, soil organic matter and carbon stock. Nematodes extracted from the soil were used for identification and quantification. Data were submitted to descriptive statistics, faunistic analysis, multidimensional scaling analysis (NMDS), similarity analysis (ANOSIM), Pearson correlation and redundancy analysis (RDA). In view of this, it was concluded in this study that the Atlantic Forest, the Caatinga and the commercial planting of coconut trees had different physical and chemical properties and composition of nematode communities. Some genera of phytoparasitic nematodes that cause major problems in agriculture are naturally found in low population density in the Caatinga and Atlantic Forest. The nematode of the genus Bursaphelenchus, which causes the red ring, was restricted to the planting of coconut trees. Soil attributes such as electrical conductivity, carbon stock and temperature influenced nematode communities. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Tese Fri, 28 Apr 2023 00:00:00 GMT http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/9416 2023-04-28T00:00:00Z http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/9415 Título: Uso de nanopartículas de prata como mitigador de estresse em plantas de arroz infectadas por Bipolaris oryzae Autor: ALMEIDA, Larissa Cavalcante Primeiro orientador: RIOS, Jonas Alberto Abstract: Rice (Oryza sativa L.) ranks third among the most cultivated cereals worldwide, playing a crucial role in food security, particularly in underdeveloped countries. However, various biotic and abiotic factors occur simultaneously in the field, causing substantial production losses, such as water stress and brown spot, caused by Bipolaris oryzae (Breda de Haan) Shoemaker. It is imperative to understand the effect of these interactions on rice plants and explore new approaches or mitigating strategies. This study aimed to: i) evaluate the effect of Silver Nanoparticles (AgNPs) in vitro and in vivo on B. oryzae and rice brown spot (BS), ii) understand the changes resulting from water stress in B. oryzae infection in rice plants, as well as the potential of AgNPs in controlling this disease in plants under both combined stresses. To evaluate the effect of AgNPs on the development of B. oryzae, in vitro tests were performed with different concentrations diluted in PDA medium (0, 5, 10, 25, 50, 100, and 200 μL L-1). The concentration with high inhibitory potential was used in the in vivo assay, under greenhouse conditions, to evaluate epidemiological (number and size of lesions, severity, and area under the disease progress curve (AUDPC)), physiological (chlorophyll (Chl) a fluorescence and concentration of photosynthetic pigments), and biochemical effects (activities of antioxidant enzymes (ascorbate peroxidase (APX), catalase (CAT), peroxidase (POX), superoxide dismutase (SOD)) and defense (phenylalanine ammonia-lyase (PAL)) in rice plants infected with B. oryzae. The experimental design used was completely randomized in a 2 x 2 x 2 factorial scheme (Evaluation time, Inoculation, and AgNPs Treatment) with four replications. The treatments used were: distilled water (control treatment) and AgNPs (5 μL L-1). Inoculation with B. oryzae was performed 24 hours after AgNPs application, using a concentration of 1 x 105 conidia mL-1. In the in vitro tests, regression adjustments for the mycelial growth rate index, mycelial diameter, and conidial germination of B. oryzae showed a reduction in these parameters as the doses of AgNPs increased, demonstrating a direct effect of AgNPs on B. oryzae. In the in vivo assay, AgNPs spraying on the plants significantly reduced the intensity of rice BS compared to the control treatment. Leaves of AgNPs-treated plants, due to lower BS severity, showed higher concentrations of Chl a and Chl b, as well as greater photosystem II quantum efficiency. Additionally, the lower cell damage due to the low level of symptoms in AgNPs-treated plants resulted in lower activities of SOD, CAT, POX, and APX. For AgNPs-treated plants, PAL activity was significantly higher compared to the control. In conclusion, the photosynthetic capacity was preserved in AgNPs-treated plants. There was a lower activity of reactive oxygen species scavenging enzymes in plants with AgNPs due to the lower level of cell infection. The increased PAL activity indicates a higher capacity for defense pathway activation in rice plants previously treated with AgNPs. To understand the changes resulting from drought stress in B. oryzae infection in rice plants, as well as the potential of AgNPs in controlling this disease in plants under both combined stresses, an in vivo experiment was conducted under greenhouse conditions, evaluating epidemiological, physiological, and biochemical parameters. The experimental design used was completely randomized in a 2 x 2 x 2 factorial scheme (Evaluation time, Inoculation, and Water Stress) with four replications. Rice plants were subjected to mild drought stress induced by PEG6000. After the stress period, the plants returned to their initial condition for 24 hours of recovery and were sprayed with AgNPs (5 μL L-1), followed by inoculation with B. oryzae using a concentration of 1 x 105 conidia mL-1. Our study demonstrated that plants subjected to drought stress showed reductions in symptoms of rice brown spot. Due to lower severity, the functionality of the photosynthetic apparatus was less affected in these plants, which exhibited higher concentrations of Chl a, Chl b, and carotenoids, as well as greater quantum efficiency of photosystem II in plants under the combination of stresses. The effect of drought stress significantly reduced the water potential of both non-inoculated and pathogen-inoculated plants. The activities of SOD and POX, as well as the proline content, increased in plants under B. oryzae infection, with a higher increase in plants previously subjected to drought stress. The activity of PAL was significantly higher in plants subjected to drought stress and inoculated with B. oryzae. Foliar spraying with AgNPs in plants under combined stresses significantly reduced the number of lesions, lesion size, severity, and AUDPC. Taken together, water stress combined with rice brown spot led to increased levels of enzymatic and non-enzymatic antioxidants, as well as higher PAL activity. Although there was a reduction in disease levels, isolated drought stress resulted in physiological harm to the plants, as indicated by the lower water potential. Foliar treatment with AgNPs reduced the epidemiological parameters of rice brown spot in combination with drought stress, indicating potential use as a stress mitigator. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Tese Sat, 28 Jan 2023 00:00:00 GMT http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/9415 2023-01-28T00:00:00Z