Development of carotenoid storage cells in Bixa orellana L. seed arils.

The arils of Bixa orellana L. seeds contain carotenoid storage cells (CSCs). The main compounds in these cells include bixin and norbixin, which are important pigments in the food and pharmaceutical industries. Although many studies have been conducted on these chemical constituents, the cellular events that occur during the development of the carotenoid-accumulating cells in the arils and their relationship with the final carotenoid accumulation in the vacuoles remain unknown. In this study, the development of the CSCs in B. orellana arils was analyzed by light and transmission electron microscopy. Carotenoids formed in specialized cells, whose number and size increased during aril development. At various stages of development, the cytoplasm of the CSCs contained chromoplasts that held an extensive network of tubules and plastoglobules. Next to the chromoplasts, lipid droplets may fuse one another to form osmiophilic bodies. In addition, vesicles were observed next to the tonoplast. At the final stages of development, both the osmiophilic bodies and vesicles, which became quadrangular or rectangular, were stored in the vacuoles of the CSCs. This study reported for the first time the occurrence of different storage unit types within the vacuole of carotenoid storage cells.

[Microsporogenesis y microgametogenesis de annatto (Bixa orellana L.)]. / Microsporogénesis y microgametogénesis de onoto (Bixa orellana L.).

A series of buds of increasing maturity were individually sampled in order to examine cytological events of annatto (Bixa orellana L.), genotype Portuguesa. They were fixed in Carnoy II at 12:30 am, time of the highest rate of meiotic division. Three stain solutions were attempted. In the microspores mother cells, the use of acetic orcein 1% resulted in a good nucleus coloration and sharpness. In contrast, a well chromosome resolution was achieved with the application of propionic carmin 2%. The pollen grain mother cells (n = 8 chromosomes) at metaphase I were found in floral buds of 0.5 to 0.6 cm long; tetrad stage in buds of 0.6 to 0.7 cm long, uninucleate stage of microspores in buds of 0.7 to 0.8 cm long and the binucleate stage (pollen) in buds longer than 0.8 cm. Microphotographies showing the sequence of meiotic division (microsporogenesis) and subsequent mitosis to originate pollen grains were included.

Microsporogénesis y microgametogénesis de onoto (Bixa orellana L. ) / Microsporogenesis and microgametogenesis of annatto (Bixa orellana L. )

A series of buds of increasing maturity were individually sampled in order to examine cytological events of annatto (Bixa orellana L.), genotype Portuguesa. They were fixed in Carnoy II at 12:30 am, time of the highest rate of meiotic division. Three stain solutions were attempted. In the microspores mother cells, the use of acetic orcein 1% resulted in a good nucleus coloration and sharpness. In contrast, a well chromosome resolution was achieved with the application of propionic carmin 2%. The pollen grain mother cells (n = 8 chromosomes) at metaphase I were found in floral buds of 0.5 to 0.6 cm long; tetrad stage in buds of 0.6 to 0.7 cm long, uninucleate stage of microspores in buds of 0.7 to 0.8 cm long and the binucleate stage (pollen) in buds longer than 0.8 cm. Microphotographies showing the sequence of meiotic division (microsporogenesis) and subsequent mitosis to originate pollen grains were included