Propriedades do pólen e do estigma de Ocimum basilicum L. (cultivar Maria Bonita) para aumentar a eficiência de cruzamentos em programas de melhoramento

Abstract

RESUMO:Ocimum basilicum, cv. Maria Bonita (Lamiaceae), conhecido como manjericão, é espécie que apresenta propriedades aromáticas, condimentares e medicinais, por ser rico em óleos essenciais. É muito usado nas indústrias farmacêuticas e de alimentos em geral. O objetivo deste trabalho foi estudar as propriedades do pólen e estigma do manjericão (cultivar Maria Bonita) identificando procedimentos simples que possam contribuir para programas de melhoramento. Para análise da disponibilidade, viabilidade do pólen e receptividade de estigma, botões florais foram coletados de hora em hora ao longo do dia, e lâminas eram montadas e coradas, para observação em microscópio óptico. Foi verificado que o manjericão apresenta antese diurna, assincrônica e com a maioria das flores se abrindo entre 10:00 e 11:00 horas. Quanto ao estudo do pólen foi verificado que a viabilidade manteve-se elevada ao longo do dia e a conservação por até 90 dias demonstrou bons níveis de viabilidade. O estigma apresentou receptividade desde a pré-antese até a pós-antese. Estas informações são relevantes para os melhoristas que desejam fazer seleção de genótipos ou hibridações em programas de melhoramento, contribuindo para aumentar o potencial da espécie que já se destaca como produtora de óleos essenciais. Palavras-chave: Ocimum basilicum, viabilidade de pólen, receptividade de estigma, conservaçãoABSTRACT: Ocimum basilicum L. (cultivar Maria Bonita) pollen and stigma properties to improve the efficiency of crossings in plant breeding programs. Known as basil, Ocimum basilicum cv. Maria Bonita (Lamiaceae) is a species that presents aromatic, condimental and medicinal properties, since it is rich in essential oils. This species is largely used in pharmaceutical and food industries. The aim of this work was to study basil (cultivar Maria Bonita) pollen and stigma properties, identifying simple procedures that can contribute to plant breeding programs. To analyze pollen availability and viability, besides stigma receptivity, flower buds were collected at every hour throughout the day, and slides were mounted, stained and observed under an optical microscope. Basil presented diurnal asynchronous anthesis and most flowers opened between 10:00 and 11:00 a.m. As regards pollen analysis, viability was high throughout the day and its conservation until 90 days was good. Stigma presented receptivity from pre-to post-anthesis. These data are relevant to breeders who wish to select genotypes or hybridizations in plant breeding programs, contributing to improve the potential of this species, which already represents a producer of essential oils.

Determination of Potential Pollinizer Grafted Pear Hybrids (Pyrus communis × Pyrus pyrifolia) for Subtropical Regions in Brazil

“…The receptive stigmatic surface and the duration of its availability is fundamental to determine the best period of pollen deposition on the flower. For successful pear fertilization, the pollen grain must present high viability and germination rate (Brito et al, 2010).…”

Pre-breeding in Passiflora subrotunda Mast.: Morphological and Reproductive Characterization at Different Light Levels

“…Studying pollen viability has a great relevance and provides basic information for species conservation and planning genetic breeding programs (Dafni, 1992;Kearns and Inouye, 1993). To initiate a breeding program, the breeder wants high pollen viability because pollen is the means of characteristics transmission to future progenies, improving or promoting new cultivar development (Brito et al, 2010). Pollen viability rate greater than 70% is considered high for passion fruit (Souza et al, 2002) and reflects a regular meiosis, once plant's meiotic behavior is directly related to fertility degree (Defani-Scoarize et al, 1995).…”

Reproductive and cytogenetic characterization in Passiflora sublanceolata

“…In protandrous species, the higher percentage of receptive stigmas is obtained at the beginning of the anthesis, when the pollen grains are released, as observed in flowers of Ocimum basilicum L., cultivar 'Maria Bonita' (Brito et al 2010), and in the lime variety 'Kagzi' (Manju & Rawat 2006). In the cultivated species, P. edulis f. flavicarpa, the percentage of receptive stigmas varies, and the time directly interferes in the receptivity reduction (Souza et al 2004a).…”

“…Although the ripening of the pollen and the stigma is an essential step for the sexual reproduction, the success of the fertilization also depends on a series of interactions between the PG and the differentiated pistil tissue (Gaude & McCormick 1999). Anyway, in P. sublanceolata, the wider period of the receptivity of the stigma favors the use of this species in hybridization programs, as it allows crossings at the most convenient moment for the program (Brito et al 2010) and assures a major percentage of success.…”