Patogenicidade de fungos associados à sementes de andropogon e caracterização morfológica e molecular de Curvularia lunata

Andropogon L. is a forage grass, widely distributed in Cerrado areas and with prolonged drought periods. It presents dense characteristics with large clumps and with plumose inflorescence, with high capacity in the seeds dissemination. In turn, seeds are considered the main sources of shelter and transport of pathogens to disease-free areas. In Tocantins, there are no studies records relate the fungi incidence in Andropogon grass seeds as diseases cause in agricultural importance crops. Likewise, there is no research about the transport, transmissibility and pathogenicity of fungi associated with their seeds. The work aim was evaluate the sanitary quality of Andropogon grass seeds, the fungi transmission by seed-seedlings and the fungis pathogenicity to other species plants of agricultural importance, and also perform the Curvularia sp. morphological and molecular characterization, isolated from Andropogon grass seeds. The experiments were conducted at the Phytopathology Research Laboratory, Biologic Control of Disease Laboratory and green house of Tocantins Federal University. In chapter 1, the blotter test method was used to evaluate seed health with and without disinfestation. The fungi incidence was evaluated from seeds individual analysis using stereoscopic and optical microscope. The seeds germination was evaluated after 10 days after test installation, together with the fungi identification associated with non-germinated seeds. For the detected fungus in the sanitary analysis was evaluated the transmission capacity of seed-seedling. The fungi pathogenicity from the Andropogon seeds grass was evaluated by inoculation in the plant itself and was also evaluated the ability of these fungi to infect other plants of economic interest. In chapter 2, the morphological identification was performed from macro and micromorphological observations using as basis the characteristics described in literature regarding the aspect of the colony and conidia of Curvularia sp. Molecular characterization was performed from DNA extraction, amplification and sequencing gene Clg2p region. Transmission was evaluated from seed sowing whitout treatment with fungicides, where at the end of 40 days typical leaf spot symptoms of Curvularia. The pathogenicity was evaluated from the inoculation of conidia suspension on leaves of healthy plants, observing at the end 10 days, if there were symptoms of the pathogen. Were identified and quantified in the seeds of Andropogon L. fungi of the genera Alternaria sp., Bipolaris sp., Curvularia sp., Fusarium sp., Phoma sp., Aspergillus sp., Cladosporium sp., Penicillium sp. and Rhizopus sp. The seed disinfestation reduced the fungi present in the seeds. The fungus Curvularia sp. it was transmitted seed to Andropogon plant. Andropogon L. seeds carried and spread fungi the once inoculated caused infection in the plant itself and other economically important crops, such as rice, cowpea, watermelon, melon, corn, sorghum and grasses marandu, mombaça, piatã and quicuia. Based on morphological and molecular markers, the fungus identified with high incidence associated with Andropogon seeds collected in different agricultural producing regions, is Curvularia lunata. C. lunata is transmitted to plants of Andropogon by seed, being pathogenic to this species of forage grass, causing foliar necrotic spots.O Andropogon L. é uma gramínea forrageira, amplamente distribuída em áreas de Cerrado e com períodos de seca prolongada. Apresenta características de ser denso com grandes touceiras e com inflorescência plumosa, tendo uma elevada capacidade na disseminação de suas sementes. Por sua vez, as sementes são consideradas principais fontes de abrigo e transporte de agentes patogênicos para áreas livres de doenças. No Tocantins, não há registros de trabalhos que relacionem a incidência de fungos em sementes de Andropogon como causadores de doenças em culturas de importância agrícola. Da mesma forma, não há pesquisas sobre o transporte, transmissibilidade e patogenicidade de fungos associados à suas sementes. O trabalho objetivou avaliar a qualidade sanitária de sementes do Andropogon, a transmissão de fungos via semente-plântula e a patogenicidade à plantas de outras espécies de importância agrícola, e também realizar a caracterização morfológica e molecular de Curvularia sp. isolados de sementes de Andropogon. Os experimentos foram conduzidos no Laboratório de Pesquisa em Fitopatologia, Laboratório de Controle Biológico de Doenças e Casa de Vegetação da Universidade Federal do Tocantins. No capítulo 1, utilizou-se o método blotter test para a avaliação da sanidade das sementes com e sem desinfestação. A incidência dos fungos foi avaliada a partir da análise individual das sementes com auxílio de microscópio estereoscópico e ótico. A germinação das sementes foi avaliada após 10 dias de instalação do teste, juntamente com a identificação de fungos associados às sementes não germinadas. Para os fungos detectados na análise sanitária avaliou-se a capacidade de transmissão via semente-plântula. A patogenicidade dos fungos oriundos das sementes de Andropogon foi avaliada por meio da inoculação na própria planta e também foi avaliada a capacidade destes fungos em infectar outras plantas de interesse econômico. No capítulo 2, a identificação morfológica foi realizada a partir de observações macro e micromorfológicas utilizando-se como base as características descritas na literatura quanto ao aspecto da colônia e conídios de Curvularia sp. A caracterização molecular foi realizada a partir da extração do DNA, amplificação e sequenciamento da região do gene Clg2p. A transmissão foi avaliada a partir da semeadura de sementes sem tratamento com fungicidas, onde ao final de 40 dias observou-se sintomas típicos de mancha foliar de Curvularia. A patogenicidade foi avaliada a partir da inoculação de suspensão de conídios de Curvularia sp. nas folhas de plantas sadias, observando ao final de 10 dias, se houve sintomas do patógeno. Foram identificados e quantificados nas sementes de Andropogon L. fungos dos gêneros Alternaria sp., Bipolaris sp., Curvularia sp., Fusarium sp., Phoma sp., Aspergillus sp., Cladosporium sp., Penicillium sp. e Rhizopus sp. A realização da desinfestação das sementes reduziu os fungos presentes nas sementes. O fungo Curvularia sp. foi transmitido das sementes para as plantas de Andropogon. As sementes de Andropogon L. transportaram e disseminaram fungos que uma vez inoculados causaram infecção na própria planta e em outras culturas de importância econômica, tais como: arroz, feijão-caupi, melancia, melão, milho, sorgo e aos capins marandu, mombaça, piatã e quicuia. Baseado em marcadores morfológicos e moleculares, o fungo identificado com elevada incidência associado às sementes de Andropogon coletadas em diferentes regiões produtoras agrícolas, trata-se de Curvularia lunata. C. lunata é transmitido para as plantas de Andropogon via semente, sendo patogênico a esta espécie de gramínea forrageira, causando manchas necróticas foliares

PERFORMANCE OF SOYBEAN CULTIVARS FOR SEED PRODUCTION IN TROPICAL FLOODPLAINS UNDER DIFFERENT GROWING CONDITIONS

Soybeans are a major crop in Brazilian agribusiness, with cultivar selection, location, and sowing date significantly impacting seed yield and quality. This study aimed to evaluate the yield and quality of soybean seeds under different growing environments, combining sowing time and location in tropical floodplain conditions in Tocantins in 2022. Four field experiments were conducted in two locations, with sowing dates of May 17 and May 31 in Lagoa da Confusão, TO. The cultivars Bônus, Extrema, Domínio, SYN1687, and SYN2282 were assessed. Each experiment followed a randomized block design with five treatments and four replications. After full maturity, the crops were harvested and evaluated for yield parameters and seed physiological quality. The cultivars Bônus, Domínio, and SYN1687 produced the highest yields, unaffected by sowing dates. However, the growing environment influenced seed vigor and viability, with the May 31 sowing favoring seed quality

Morphological and molecular characterization of Curvularia lunata pathogenic to andropogon grass

<div><p>ABSTRACT The fungal genus Curvularia is associated with a number of diseases in plants, commonly producing foliar spots in forage grasses. The objective of this study was to characterize the morphological and molecular diversity of the isolates of Curvularia sp. associated with Andropogon seeds, and to assess both their capacity to transmit disease and the pathogenicity of this fungus to crop. Ten isolates of Curvularia sp. were sourced from Andropogon seeds from agricultural producing regions in the Brazilian states Tocantins and Pará. Morphological characterization was achieved by observing fungus colonies and conidia and molecular characterization by DNA extraction and amplification with sequence-specific primers. The disease transmission was evaluated from seed sowing, in which after 40 days typical symptoms of Curvularia sp. were observed. Pathogenicity was evaluated by inoculating conidial suspension into the leaves of healthy plants, and after ten days, inspecting for pathogenic symptoms. Based on morphological and molecular features, the pathogen associated with Andropogon seeds was identified as Curvularia lunata, which, as such, is transmitted through the Andropogon plants via its seeds and is pathogenic to this species of forage grass.</p></div

Morphological and molecular characterization of Curvularia lunata pathogenic to andropogon grass

<div><p>ABSTRACT The fungal genus Curvularia is associated with a number of diseases in plants, commonly producing foliar spots in forage grasses. The objective of this study was to characterize the morphological and molecular diversity of the isolates of Curvularia sp. associated with Andropogon seeds, and to assess both their capacity to transmit disease and the pathogenicity of this fungus to crop. Ten isolates of Curvularia sp. were sourced from Andropogon seeds from agricultural producing regions in the Brazilian states Tocantins and Pará. Morphological characterization was achieved by observing fungus colonies and conidia and molecular characterization by DNA extraction and amplification with sequence-specific primers. The disease transmission was evaluated from seed sowing, in which after 40 days typical symptoms of Curvularia sp. were observed. Pathogenicity was evaluated by inoculating conidial suspension into the leaves of healthy plants, and after ten days, inspecting for pathogenic symptoms. Based on morphological and molecular features, the pathogen associated with Andropogon seeds was identified as Curvularia lunata, which, as such, is transmitted through the Andropogon plants via its seeds and is pathogenic to this species of forage grass.</p></div

Compostos de Morinda citrifolia como indutores de respostas bioquímicas em plantas de melão. : Morinda citrifolia compounds such elicitor substances of biochemical responses in melon plants.

Plants have complex structural and biochemical defense mechanisms that can be activated before orafter the attack of phytopathogenic microorganisms. Among these mechanisms are the proteins related tothe pathogenesis (PRP) and the hypersensitive response through the production of reactive oxygen species(ROS), which exist in enzymes capable of reducing its toxicity to the plant. In addition to activation induced bybiotic or abiotic factors, such as compounds or substances that stimulate biochemical activity, called elicitorsubstances, such as essential oils and their constituents. Studies in the area are necessary to deepen knowledgeand reach the technical and economic feasibility of its use for the benefit of sustainable agriculture. The aimwas to evaluate the enzymatic activity of melon plants submitted to the noni essential oil application (EO) andoctanoic acid (OA). In different treatment concentrations, as well as fungicide Cerconil® (0.2%) and Yantra®plant stimulant. The enzymes that had their activity evaluated were superoxide dismutase (SOD), chitinase(QUIT), ascorbate peroxidase (APX), and catalase (CAT). Octanoic acid (0.1%) and essential oil (0.5%) were theprimary activators of the enzyme superoxide dismutase among the treatments tested. The enzyme ascorbateperoxidase had its production increased by the octanoic acid at 0.1%. EO was the primary activator of thecatalase enzyme at 2% concentration. The secondary metabolites activity of the Morinda citrifolia againstmicroorganisms and as an activator of the defense system were confirmed, considered a potential compoundfor developing a bioproduct as a substitute for pesticides.As plantas apresentam mecanismos complexos de defesa estrutural e bioquímica que podem ser ativados antes ou após o ataque de microrganismos fitopatogênicos. Dentre esses mecanismos, estão as proteínas relacionadas à patogênese (PRP) e a resposta hipersensível através da produção de espécies reativas de oxigênio (ERO), as quais auxiliam na defesa contra os fitopatógenos e redução da toxicidade dos radicais livres. A ativação deste sistema pode ser por fatores bióticos ou&nbsp; abióticos que podem estimular a atividade bioquímica, denominadas substâncias elicitoras, como óleos essenciais e seus constituintes. Estudos na área são necessários para aprofundar conhecimento e atingir a viabilidade técnica e econômica de seu uso em benefício da agricultura sustentável. Objetivou-se avaliar a atividade enzimática de plantas de meloeiro submetidas à aplicação de óleo essencial de noni (OE) e ácido octanóico (AO). Foram testadas diferentes concentrações dos tratamentos e como testemunhas: fungicida Cerconil® (0,2%) e &nbsp;estimulante vegetal Yantra®. As enzimas com atividade avaliada foram superóxido dismutase (SOD), quitinase (QUIT), ascorbato peroxidase (APX) e catalase (CAT). O ácido octanóico (0,1%) e óleo essencial (0,5%) foram os maiores ativadores da SOD dentre os tratamentos testados. A APX teve sua produção aumentada pela aplicação de ácido octanóico à 0,1%. O OE foi o maior ativador da CAT na concentração de 2%. Confirmando a atividade dos metabólitos secundários de Morinda citrifolia como ativadores do sistema de defesa e provável ação imediata contra microrganismos. Considerando assim compostos potenciais para o desenvolvimento de um bioproduto como substituto de defensivos agrícolas. &nbsp; Palavras-chave: bioprodutos, compostos naturais, Cucumis melo L., espécies reativas de oxigênio, óleo essencial

163 Ciência Rural

ABSTRACT The aim of this study was to determine the most adequate stocking density for tambatinga during the initial grow-out phase in net pen