Optimizing Shoot Propagation Methods in Tropical Yam - Dioscorea alata

Abstract

Genetic study of yam has been hindered for a plethora of reasons, thus slowing typical agronomic improvement. A key gap in yam is the ability to reliably produce healthy yam plants year-round for genetic study, breeding, and improvement of food security. My research aims to optimize shoot propagation methods using tissue culture technology to create this reliable source of plant material. Previous work has shown that shoot propagation of Dioscorea is possible, however, it has proven to be genotype and explant dependent. My aim is to optimize upon previous work specifically for the genotypes of economic and dietary value in the Tropical Pacific Islands. The current state of the art method was able to achieve 64.77% in similar genotypes. Here two genotypes within the species Dioscorea alata were examined. The first genotype is a white fleshed tuber variety Dioscorea alata v. Lyon W-1, the second was a violet fleshed tuber variety Dioscorea alata v. ‘purpurea’ commonly known as Ube in the tropical Pacific. Individual responses to different sterilization methods, culture media, and long-term storage methods in vitro were examined. Sterilization with treatment 2 found a 16.6% contamination rate using safe widely available reagents. Murashige and Skoog (MS) media, treatment 1 with cytokine hormone addition at a concentration of 10 uM Kinetin produced the highest rate of complete organogenesis from explant in D. alata v. Lyon W-1 and D. alata purpurea v Ube genotypes were examined at 87%, and 66% respectively after 35 days. Long-term storage treatment 2 with drastic reserialization after organogenesis produced a 19% contamination/Necrosis rate after 120 days.