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    Physiological, biochemical, and yield responses of bean plants to water deficit: contrasts between species and bacterial modulation.
    (Universidade Federal de Viçosa, 2026-09-17) Lopez, Deisy Johana Cuellar; Ribeiro, Dimas Mendes; http://lattes.cnpq.br/9378076016309841
    Water deficit constrains legume productivity, yet the physiological strategies underlying interspecific variation in drought tolerance and the extent to which beneficial bacteria can enhance crop resilience remain poorly integrate. Here, a comparative physiological approach across species was used to identify mechanisms of drought tolerance in beans and determine whether the extremophilic bacterium Pseudomonas alcaligenes Med1 improves drought resilience in common bean. In a first experiment, Phaseolus vulgaris and Vigna unguiculata were subjected to progressive water deficit followed by rehydration. In a second experiment, non- inoculated and Med1-inoculated P. vulgaris cv. Palo plants were evaluated throughout vegetative and reproductive development under well-watered and water- deficit conditions. V. unguiculata displayed earlier stomatal regulation and better preserved plant water status, photosynthetic pigments, cytokinins, and carbon balance during drought. Together with enhanced antioxidant capacity, these responses supported rapid post-drought recovery and maintained yield. By contrast, P. vulgaris experienced greater dehydration, depletion of carbon reserves, and loss of pigments and cytokinins, with persistent physiological impairment after rehydration and consequent reductions in biomass and yield. Inoculation with Med1 improved water status and intrinsic water-use efficiency in P. vulgaris and induced antioxidant and osmoprotective adjustments, particularly during reproductive development. However, these responses were insufficient to prevent drought-induced photosynthetic and yield limitations. Notably, Med1 increased sugar, protein, and amino acid contents in developing seeds and enhanced P, Ca, Fe, and Zn concentrations in mature seeds, irrespective of water availability. These findings reveal that drought tolerance in V. unguiculata relies on coordinated stomatal regulation, water conservation, maintenance of carbon resources, and post-stress recovery, whereas Med1 provides targeted physiological and nutritional benefits rather than complete protection against water deficit in P. vulgaris cv. Palo. These results highlight the importance of integrating intrinsic plant drought-adaptation strategies with microbial approaches to improve legume resilience. Keywords: Phaseolus vulgaris; Vigna unguiculata; Pseudomonas alcaligenes Med1; water deficit.
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    Impacto de estratégias de ponderação de marcadores na seleção genômica
    (Universidade Federal de Viçosa, 2026-02-25) Pereira, Guilherme Flaviano; Azevedo, Camila Ferreira; http://lattes.cnpq.br/8957073729245293
    O avanço da seleção genômica ampla (Genome-Wide Selection – GWS) tem pro- porcionado ganhos expressivos em programas de melhoramento genético ao permi- tir a predição de valores genéticos com base em marcadores moleculares distribuí- dos ao longo do genoma. O método Genomic Best Linear Unbiased Prediction (G- BLUP) é um dos mais utilizados em GWS devido à sua eficiência computacional e à capacidade de lidar com a alta dimensionalidade dos dados. Entretanto, o G-BLUP assume contribuição homogênea dos marcadores na construção da matriz de pa- rentesco genômico, desconsiderando diferenças na importância dos marcadores e sua associação com os loci causais. Nesse contexto, este estudo teve como objetivo avaliar o impacto de diferentes estratégias de ponderação de marcadores molecula- res sobre parâmetros genéticos e estatísticos ao longo de ciclos de seleção genômi- ca recorrente. Foram considerados pesos derivados de estudos de associação ge- nômica ampla (GWAS), do método BayesB e de medidas de associação entre mar- cadores, como desequilíbrio de ligação (LD), LD-score e fator de inflação da variân- cia (VIF). Dados simulados foram gerados considerando diferentes arquiteturas ge- néticas e níveis de herdabilidade em um programa com 30 ciclos de seleção recor- rente. O desempenho das estratégias foi avaliado por meio da acurácia preditiva, viés, concordância dos melhores indivíduos, ganho genético, diversidade genética e endogamia. Os resultados demonstraram que a eficiência das estratégias de ponde- ração depende da arquitetura genética da característica e da métrica avaliada, não havendo uma abordagem universalmente superior ao G-BLUP tradicional. De modo geral, a ponderação exerceu pouca influência sobre o ganho genético, mas favore- ceu, em determinados cenários, maior preservação da diversidade genética e menor endogamia. Estratégias que combinaram medidas de importância dos marcadores com informações de associação entre marcadores apresentaram os resultados mais consistentes. Conclui-se que a ponderação da matriz de parentesco genômico cons- titui uma estratégia complementar ao G-BLUP tradicional, cuja adoção deve consi- derar os objetivos específicos do programa de melhoramento, especialmente quan- do se busca conciliar resposta à seleção e manutenção da variabilidade genética. A dissertação está organizada em duas seções. A primeira apresenta a fundamentação teórica da seleção genômica, com ênfase no modelo G-BLUP, nas estratégias de ponderação de marcadores, nas medidas de associação entre marcadores e nas métricas utilizadas para avaliação dos modelos. A segunda descreve, por meio de dados simulados, a avaliação comparativa de diferentes estratégias de ponderação da matriz de parentesco genômico sobre parâmetros genéticos e estatísticos ao longo de ciclos de seleção genômica recorrente. Palavras-chave: G-BLUP; seleção genômica recorrente; arquitetura genética; ponderação de marcadores; matriz de parentesco genômica.
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    Genetic diversity and activity of Metarhizium spp. in coffee systems of the Cerrado of Minas Gerais
    (Universidade Federal de Viçosa, 2026-03-31) Mendonça, Lais Viana Paes; Venzon, Madelaine; http://lattes.cnpq.br/4691443466455559
    Tropical coffee cultivation faces growing sustainability challenges due to the biological simplification of monoculture and the intensification of extreme weather events. Regenerative systems enhance the ecosystem service of biological control by maintaining natural enemies and improving soil health. Entomopathogenic fungi of the genus Metarhizium are favored in these systems, where habitat complexity supports their multifunctional lifestyles such as saprophytes, growth-promoting endophytes, and biological control agents. To understand how plant diversification maintains these fungal populations at real-world production levels, this study investigates how regenerative coffee systems in the Cerrado of Minas Gerais affect the conservation, population genetic structure, and functional activity of Metarhizium spp. This study was based on isolates obtained from two complementary sources: an isolate bank originating from experimental regenerative coffee systems implemented in 2019 and evaluated until 2021, and new samplings carried out from 2023 to 2025 in 12 commercial coffee farms in the region. In Chapter 1, we characterized the genetic diversity of the genus Metarhizium through population structure and multilocus phylogeny, confirming the predominance of Metarhizium robertsii and M. brunneum, and evaluated the effects of management, temporal variation, and microhabitats on haplotype distribution. We found that the M. robertsii haplotype h1 is predominant in coffee crops in the Cerrado of Minas Gerais, regardless of management, season, or microhabitat. Furthermore, we observed that the regenerative system harbored exclusive strains, such as haplotype h2 of M. robertsii and two isolates of M. brunneum. In Chapter 2, we evaluated the functional dimension of this diversity through the entomopathogenic activity of these isolates, using insect bait bioassays (Tenebrio molitor). While the monoculture showed drastic fluctuations in T. molitor mortality in 2025, the regenerative system maintained stable entomopathogenic activity. Thus, the results of this thesis highlight that strategic plant diversification of coffee crops in the Cerrado of Minas Gerais conserves native strains with high symbiotic potential, while also increasing the genetic complexity and functional stability of Metarhizium in the soil over time. Therefore, the transition to regenerative systems establishes itself as a viable and necessary alternative to conventional monoculture, ensuring sustainability in coffee production by maintaining ecosystem services provided by these fungi and by bioprospecting promising metarhizium spp. strains for the development of new biological inputs. Keywords: Ecosystem services; Conservative Biological Control; Haplotypes; Entomopathogenic fungi.
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    Genetic diversity and ecological modelling of the invasive gall wasp Ophelimus maskelli (Hymenoptera: Eulophidae) across native and invaded ranges
    (Universidade Federal de Viçosa, 2026-06-29) Afonso Neto, Paulo Cesar; Cristiano, Maykon Passos; http://lattes.cnpq.br/6127936044829841
    Biological invasions represent an increasing threat to biodiversity, forest production, and the stability of managed ecosystems. This thesis investigates the invasion risk, evolutionary history, and phylogeographic structure associated with Ophelimus maskelli, an Australian gall-inducing wasp related to damage in Eucalyptus species. The study combines potential distribution modelling, molecular, phylogenetic, and phylogeographic analyses to understand the processes that favor the dispersal, establishment, and identification of invasive lineages. Ecological modelling, based on MaxEnt and CLIMEX, evaluated the climatic suitability of O. maskelli under current and future conditions, with emphasis on the risk to Eucalyptus plantations in Brazil. The results indicate climatically favorable areas for the species and highlight differences between correlative models and climate-matching approaches, allowing a broader assessment of its establishment potential. The integration of climatic distribution, Eucalyptus cultivation areas, and possible dispersal routes contributes to the identification of priority regions for phytosanitary monitoring. Subsequently, sequences of the mitochondrial COI gene were used to reconstruct evolutionary relationships and validate diagnostic regions with potential application in molecular identification. The molecular analyses showed that the Ophelimus complex includes genetically distinct lineages, some of which may have been previously misidentified as O. maskelli, reinforcing the importance of molecular approaches to reduce taxonomic identification errors in occurrence records. This thesis demonstrates that the combination of ecological modelling, phylogeography, and DNA barcoding provides a robust framework for understanding biological invasions in insects associated with planted forests, while also supporting strategies for surveillance, management, and prevention of new introductions. Keywords: Ophelimus maskelli; Biological invasion; Ecological modelling; Eucalyptus; Phylogeography; DNA barcoding.
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    Fermentation of Coffea arabica by lactic acid bacteria: development of infusions from fermented cascara and evaluation of fermentative exudates
    (Universidade Federal de Viçosa, 2026-07-31) Lins, João Paulo de Melo; Felix, Pedro Henrique Campelo; http://lattes.cnpq.br/1053432375329889