Identificação morfológica e transmissão de fungos em sementes de olerícolas
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Data
2017-12-01
Autores
Pierozzi, Caroline Geraldi
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A identificação morfológica e a transmissão de fungos são dois ramos importantes da Patologia de Sementes. As chaves interativas, que têm como base a morfologia fúngica, auxiliam a pesquisa e trabalhos técnicos, de forma que a identificação digital se torne mais presente. Por este método, desenvolveu-se uma chave interativa que auxilie a identificação de onze espécies fúngicas associadas às sementes de cebola, cenoura, pimentão e tomate. Esta baseou-se em uma matriz composta por seis caracteres: cultura, conídio, conidióforo, coloração do conidióforo longo, coloração do micélio e presença ou não de setas. O usuário seleciona respostas aos caracteres oferecidos no software e o microrganismo é corretamente indicado. A validação desta ferramenta foi realizada por meio de teste com grupos de voluntários compostos por alunos de graduação e pós-graduação. Analisou-se o tempo despendido por cada voluntário para analisar 25 sementes com fungos comuns aos da chave, como também a porcentagem de acerto e o grau de dificuldade de cada participante. Os resultados foram confrontados com um grupo controle, o qual utilizou o meio convencional (manuais impressos de identificação). A elevada porcentagem de acertos na diagnose com o auxílio da chave e a classificação de fácil uso pelos usuários confirmou a eficiência do método. Também observou-se um aumento da acurácia dos resultados quando comparado ao sistema convencional. Além disso, esta chave pode ser útil em vários setores, desde auxiliar no treinamento de iniciantes na Patologia de Sementes até em atividades acadêmicas. Já para o estudo da transmissão de fungos via sementes, foram necessários tanto os conhecimentos morfológicos quanto os moleculares. Neste sentido, avaliou-se a transmissão das três raças de Fusarium oxysporum f. sp. lycopersici (FOL) por sementes de tomate. Foram utilizados dois isolados de cada raça e para cada um deles foram inoculadas 200 sementes em suspensão de esporos à concentração de 107esporos/mL. Estas sementes foram semeadas em bandejas com células e mantidas sob condições controladas até completarem três semanas após a emergência. Foram avaliadas 100 plântulas por isolado quanto a massa, comprimento de raízes e severidade. Além disso, pequenos fragmentos da parte aérea e raiz, de cada plântula, foram plaqueados em meio de cultura para posterior análise molecular e confirmação da transmissão. Analisou-se também a eficiência do tratamento de sementes de tomate com ácido clorídrico (HA) e fosfato trissódico (TSP) no controle de FOL. Para isso, foram utilizados três lotes de sementes, cada um deles inoculado com uma raça diferente de FOL e tratados com os diferentes tratamentos. Os resultados demonstraram baixa taxa de transmissão para as raças 1 e 3 e nula para a raça 2. Em relação aos resultados de massa das plântulas e comprimento de raízes, notou-se que o baixo desenvolvimento de plântulas é inversamente proporcional a elevada transmissão. Além disso, a doença apresenta-se de forma assintomática em plântulas. Ao analisar os resultados dos tratamentos de sementes, constatou-se que o ácido clorídrico foi 100% eficiente no controle de FOL, enquanto que o fosfato trissódico não controlou as raças de FOL.
Morphological identification and fungi transmission are two important Seed Pathology branches. Interactive keys, based on fungal morphology, help research and technical work, so that digital identification becomes more present. Through this method, an interactive key was developed to help identify eleven fungal species associated with carrot, onion, pepper and tomato. It was based on a matrix composed by six characters: crop, conidium, conidiophore, long conidiophore coloration, mycelial staining and presence of setae. The user selects responses to the features offered in the software and the micro-organism is correctly indicated. The validation was performed through volunteers groups composed of undergraduate and graduate students. It was analysed the time spend by each volunteer to examine 25 seeds with fungi common to the key, as well as the percentage of hits and the difficulty level of each participant. The results were compared with a control group, which used the conventional means (printed identification manuals). The high percentage of correct answers in the diagnosis with the key use and the user easy classification confirmed its efficiency. There was also an increase in the results accuracy when compared to the conventional system. In addition, this key can be useful in many sectors, from assisting in training beginners in seed pathology to academic activities. For the study of fungi transmission through seeds, both morphological and molecular knowledge were necessary, which made the result safer. In this sense, the three races of Fusarium oxysporum f. sp. lycopersici transmission by tomato seeds were analyzed. Two isolates of each race were used and 200 seeds were inoculated in spore suspension at 107 spores/mL concentration. These inoculated seeds were planted in trays with individual cells and kept under controlled light and humidity conditions until completed three weeks after emergence. The evaluation consisted in weight, root length and severity from 100 seedlings. In addition, small parts of the shoot and root of each seedling were plated in medium culture for further molecular analysis and confirmation of the transmission. The efficiency of tomato seed treatment with hydrochloric acid (HA) and trisodium phosphate (TSP) in FOL control was also analyzed. For this, three seed lots were used, each one inoculated with a different race of FOL and treated with the different treatments. The results showed a low transmission rate for races 1 and 3 and null for race 2. Regarding the results of seedling mass and the root length, it was observed that the low seedling development is inversely proportional to high transmission. In addition, the disease presents asymptomatically in seedlings. When analyzing the seed treatments results, it was verified that hydrochloric acid was 100% efficient in the FOL control, whereas trisodium phosphate did not control the FOL race.
Morphological identification and fungi transmission are two important Seed Pathology branches. Interactive keys, based on fungal morphology, help research and technical work, so that digital identification becomes more present. Through this method, an interactive key was developed to help identify eleven fungal species associated with carrot, onion, pepper and tomato. It was based on a matrix composed by six characters: crop, conidium, conidiophore, long conidiophore coloration, mycelial staining and presence of setae. The user selects responses to the features offered in the software and the micro-organism is correctly indicated. The validation was performed through volunteers groups composed of undergraduate and graduate students. It was analysed the time spend by each volunteer to examine 25 seeds with fungi common to the key, as well as the percentage of hits and the difficulty level of each participant. The results were compared with a control group, which used the conventional means (printed identification manuals). The high percentage of correct answers in the diagnosis with the key use and the user easy classification confirmed its efficiency. There was also an increase in the results accuracy when compared to the conventional system. In addition, this key can be useful in many sectors, from assisting in training beginners in seed pathology to academic activities. For the study of fungi transmission through seeds, both morphological and molecular knowledge were necessary, which made the result safer. In this sense, the three races of Fusarium oxysporum f. sp. lycopersici transmission by tomato seeds were analyzed. Two isolates of each race were used and 200 seeds were inoculated in spore suspension at 107 spores/mL concentration. These inoculated seeds were planted in trays with individual cells and kept under controlled light and humidity conditions until completed three weeks after emergence. The evaluation consisted in weight, root length and severity from 100 seedlings. In addition, small parts of the shoot and root of each seedling were plated in medium culture for further molecular analysis and confirmation of the transmission. The efficiency of tomato seed treatment with hydrochloric acid (HA) and trisodium phosphate (TSP) in FOL control was also analyzed. For this, three seed lots were used, each one inoculated with a different race of FOL and treated with the different treatments. The results showed a low transmission rate for races 1 and 3 and null for race 2. Regarding the results of seedling mass and the root length, it was observed that the low seedling development is inversely proportional to high transmission. In addition, the disease presents asymptomatically in seedlings. When analyzing the seed treatments results, it was verified that hydrochloric acid was 100% efficient in the FOL control, whereas trisodium phosphate did not control the FOL race.
Descrição
Palavras-chave
Patologia de sementes, Chave de identificação, Fungos fitopatogênicos