In vitro Propagation of Bulblets and Elimination of Viruses by Bulb-scale Cultures of Hippeastrum hybridum Bulbs.

Abstract

The effect of in vitro culture conditions on bulblet regeneration of bulb-scale explants excised from Hippeastrum bulbs and the possibility of virus elimination by this method were investigated. Explants containing the extreme base of bulb-scale produced bulblets at a high rate. Bulblet regeneration was stimulated on White's (1943) agar medium supplemented with 0.01mg/l α-naphthaleneacetic acid(NAA) and 5.0mg/l 6-ben-zylaminopurine (BA). In these cases, a high regeneration rate was found for explants with 2-mm cuts treatment on their proximal ends. Bulblet multiplication was stimulated by subculturing the bulblets formed on the bulb-scale base explants in liquid White's medium with shake-culture. Especially, in the subculture, the bulblets with notching treatment on their bases produced the largest number of new bulblets. Based on these results, a mass propagation scheme for Hippeastrum using a shake culture has been established.In bulblets obtained from the bulb-scale base explant culture, almost all the bulblets were cucumber mosaic virus (CMV) -free by dot immunobinding assay (DIBA), and in 33% of the bulblets hippeastrum mosaic virus (HiMV) was detected by the direct negative staining method. However, all of the new bulblets obtained from the subculture of the bulblets were free of both viruses. These results indicate that the method developed in this study can be utilized as a novel method for the in vitro propagation of virus-free plants.