RESUMO Sementes mantidas dentro de frutos carnosos, após a colheita, podem continuar metabolicamente ativas, sem interromper o processo de maturação, o que pode promover aumento das taxas de germinação e do vigor. Também, durante a maturação e o repouso pós-colheita dos frutos, podem ocorrer alterações nos mecanismos de proteção contra danos oxidativos, incluindo a atividade das enzimas antioxidantes. Objetivou-se, com este trabalho, avaliar a qualidade fisiológica e a atividade de enzimas do sistema de defesa antioxidativo em sementes de pimentas Capsicum chinense Jacq. representada pela pimenta Biquinho e Capsicum frutescens L representada pela Malagueta, de frutos colhidos em diferentes estádios de maturação e submetidos ao repouso pós-colheita. Frutos colhidos aos 40, 55 e 70 dias após antese (DAA) foram armazenados em câmara, a 25 °C, por 0, 6, 12 e 18 dias. As sementes extraídas dos frutos foram avaliadas pelos testes de germinação e de envelhecimento acelerado. Também, foram determinadas as atividades das enzimas superóxido dismutase, catalase e peroxidase. Para ambas as espécies, sementes de frutos colhidos aos 70 DAA, com coloração vermelha, apresentaram taxas de germinação e vigor superiores aos daquelas de colheitas anteriores, aos 40 e 55 DAA. A colheita neste estádio é recomendada para obtenção de sementes de alta qualidade fisiológica. O repouso dos frutos de pimenta Biquinho colhidos aos 55 DAA contribui para aumentar o potencial de germinação das sementes, enquanto, para os de pimenta Malagueta esse procedimento é pouco benéfico. A enzima catalase tem grande potencial para o monitoramento da qualidade fisiológica das sementes de pimentas Malagueta e Biquinho; a baixa atividade dessa enzima em sementes oriundas de frutos em repouso está relacionada com sua maior qualidade fisiológica.

ABSTRACT Seeds held inside fleshy fruits after harvest can continue metabolically active, the process of maturation is not interrupted, which can promote the increase on germination and vigour. Also, during maturation and fruit after-ripening period, changes in the mechanisms of protection against oxidative damage can occur, including the activity of antioxidant enzymes. The aim of this study was to evaluate the physiological quality and enzymatic activity of antioxidant defense system of Capsicum chinense Jacq. Represented by the Biquinho pepper and Capsicum frutescens L. represented by the Malagueta pepper seeds, collected from fruits at different developmental stages and subjected to post-harvest storage. Fruits harvested at 40, 55 and 70 days after anthesis (DAA) were stored at 25 °C, for 0, 6, 12 and 18 days. Seeds were evaluated for germination and accelerated aging tests. In addition, the activities of superoxide dismutase, catalase and peroxidase were determined. For both species, seed from fruits collected at 70 DAA, presenting red colour, have higher germination and vigour compared to the seeds harvested at 40 and 55 DAA. The harvest of the fruits on this stage is recommended for obtain high quality seeds. The after-ripening of Biquinho pepper seeds harvested at 55 DAA contribute to increase the germination potential of the seed, while for Malagueta seeds this procedure has little benefit. The catalase enzyme has great potential to monitor the physiological quality of Biquinho and Malagueta pepper seeds; low activity of this enzyme in seeds during the fruits after-ripening is related to better physiological quality.

Two endophytic strains of Methylobacterium spp. were used to evaluate biofilm formation on sugarcane roots and on inert wooden sticks. Results show that biofilm formation is variable and that plant surface and possibly root exudates have a role in Methylobacterium spp. host recognition, biofilm formation and successful colonization as endophytes.

The colonization of Spodoptera frugiperda J.E. Smith larvae and rice seedlings by genetically modified endophytic bacterium Methylobacterium mesophilicum, and also the possible transfer of this bacterium to inside the larva's body during seedlings consumption were studied. The data obtained by bacterial reisolation and fluorescence microscopy showed that the bacterium colonized the rice seedlings, the larva's body and that the endophytic bacteria present in seedlings could be acquired by the larvae. In that way, the transference of endophytic bacterium from plants to insect can be a new and important strategy to insect control using engineered microorganisms.