Effect of glycerol as a cryoprotectant for castor bean pollen for different storage periods

Abstract

The cultivation of castor bean (Ricinus communis) in Brazil has been considered strategic due to the enormous increase of its use in the production of biodiesel. Cryopreservation shows a great potential to preserve cultivars or varieties of this species. Considering the importance of using pollen grains as conservation elements of genetic resources, the objective of this study was to evaluate the effect of different glycerol concentrations to cryoprotect the castor bean pollen grains submitted to liquid nitrogen (-196°C) for different storage periods. Pollen grains with 5-7% relative moisture content were cryoprotected with a 0, 5, 10 and 15% glycerol solution and directly immersed in liquid nitrogen for one hour, 15, 30 and 180 days. Cytological viability of pollen grains using 2% acetic carmine as dye was evaluated. Viable, non-viable and burst pollen grain numbers were analyzed. After the maximum storage period (180 days) in liquid nitrogen, the pollen grains maintained their viability above 60%. This confirms the possibility of cryopreservation by using the glycerol cryoprotectant as a viable alternative for the preservation of R. communis pollen grains at ultra-low temperature.