In vitro regeneration of Sugar Beet (Beta vulgaris L.) via leaf explants and callusing

Abstract

Sugar beets (Beta vulgaris L.) represent a major segment of the sweetener industry in the United States.  The Southwest region and the Texas portion of the Great Plains region are the only ones that have experienced a decline in production in the past 15 years. Although numerous factors have contributed to this decline, in a large part it has been due to rhizomania, a devastating disease of sugar beets caused by Beet Necrotic Yellow Vein Virus (BNYVV). The objective of this research was to develop a standardized reproducible technique to regenerate plantlets via in vitro culture that can be used for screening the disease resistant varieties of this important crop. Various combinations and concentrations of auxins and cytokinins were tested to induce dedifferentiation of the somatic cells. We recorded the regeneration of plantlets directly from the leaf explants. The leaf explants showed shooting and rooting directly when cultured on IAA (0.5 mg/l) and BAP (2 mg/l). The callus culture with 6, BAP (1.5 mg/l) and IAA (0.2 mg/l) led to the formation of the heart shaped or “T” shaped or “Y” shaped embryoids that exhibited high level of totipotency. The embryoids followed rooting in MS medium supplemented with IAA (0.2 mg/l). Root formation and shoot formation either directly from the explants or from regenerable callus were observed.  Modification and refinement of in vitro techniques allowed us to obtain regenerable callus that had the capability of entire plant regeneration. This technique was successfully implemented to regenerate plantlets that showed 63% survival.