Abstract
The objective of this work was to characterize the morphology and viability of the pollen of 15 genotypes of castor bean (Ricinus communis L.) and to generate information that can assist in the selection of highly promising male parents for future use in genetic improvement programs aimed at producing seeds for oil extraction. Acetolysis and scanning electron microscopy was used to characterize the morphology of the pollen. The viability of the pollen grains was estimated by in vitro germination and colorimetric analysis (acetocarmine 2% and 2, 3, 5-triphenyltetrazolium chloride 1%). For the in vitro germination, pollen grains were grown in 10 types of solidified culture medium consisting of different concentrations of sucrose, boric acid, calcium nitrate, magnesium sulfate and potassium nitrate. The pollen grains had the following characteristics: medium size, isopolar and subspheroidal shape, radial symmetry, circular ambit, 3-colporate, elongated endoapertures, tectate exine and granulated sexine. The acetocarmine dye overestimated pollen viability. The media M5 and M8 were the most efficient at promoting the germination of pollen grains. The studied genotypes had high levels of viability and can therefore be used as male parents in genetic improvement programs.
Highlights
With growing demand for renewable and cleaner energy sources to produce oil for biodiesel, the castor bean (Ricinus communis L.) is being considered as a good option for farmers.Plant-breeding techniques can be used to obtain new, more productive varieties that often differ in seasonality; these plants are of great value in selective breeding programs, as they can enable the storage, transportation and maintenance of pollen grains with high viability (Vargas, Souza, Silva, & Bobrowski, 2009).Acta Scientiarum
The objective of this study was to characterize the morphology and to investigate the viability of pollen from fifteen castor bean genotypes and to generate information that can assist in the selection of highly promising male parents for future use in genetic improvement programs aimed at producing seeds for oil extraction
Pollen grains from male flowers were collected at anthesis from fifteen castor bean genotypes developed by the ‘Empresa Baiana de Desenvolvimento Agrícola’: MPA11, MPA17, MPA18, MPA26, MPA31, MPA34, MPA35, MPA36, MPA37, MPA38, MPA39, MPA40, MPA41, MPA42 and MPA43; these genotypes are kept at the experimental area of the ‘Núcleo de Melhoramento Genético e Biotecnologia’, Cruz das Almas, Bahia State, Brazil
Summary
With growing demand for renewable and cleaner energy sources to produce oil for biodiesel, the castor bean (Ricinus communis L.) is being considered as a good option for farmers.Plant-breeding techniques can be used to obtain new, more productive varieties that often differ in seasonality; these plants are of great value in selective breeding programs, as they can enable the storage, transportation and maintenance of pollen grains with high viability (Vargas, Souza, Silva, & Bobrowski, 2009).Acta Scientiarum. The in vitro germination of pollen grains is the most commonly used viability assay in genetic improvement programs, as it simulates the stylestigma interaction, induces the growth of pollen tubes (Soares, Jesus, Souza, Santos-Serejo, & Oliveira, 2013), promotes fertilization and allows crossings between high quality genotypes that flower at different times. This technique has been widely studied in several species (Cuchiara et al, 2012; Machado et al, 2014), including oleaginous species such as the castor bean, cotton, soy, canola (rapeseed), oil palm, sunflower, babassu palm and peanuts. The basic medium used for in vitro assays consists of sucrose, boric acid and a variety of other substances (Zambon, Silva, Pio, Figueiredo, & Silva, 2014)
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