Genetic Transformation for Improvement of Yam

Yam (Dioscorea spp.), is an important crop in the tropics and subtropics providing food security and income to over 300 million people. Despite the economic and socio-cultural importance, yam cultivation is generally limited by high costs of planting material, decreasing soil fertility, inadequate yield potential of yam varieties, field and storage pests and diseases. Nematodes are particular of concern as they manifest during storage and facilitate tuber rot by fungi and bacteria. Most biotic constraints affect seed productivity and viability, reducing germination, plant vigor and yield. The use of resistant and healthy seed material is therefore crucial for high and sustainable yam production, as yam is a clonally propagated crop. Genetic engineering offers a powerful tool, complementing conventional breeding approaches, for development of resistant varieties. Although genetic transformation of clonally propagated crops has been widely studied as a tool for crop improvement and as a vital part of the development of functional genomics resources, there has been no report of any existing Agrobacterium-mediated transformation of yam (Dioscorea spp.) with evidence of stable integration of T-DNA. Here, we report development of an Agrobacterium-mediated transformation of Dioscorea rotundata using reporter genes. Transgenic plants were regenerated on antibiotic selection medium. Successful transformation was confirmed by PCR, Southern blot analysis and reporter genes assay. We will present an efficient, fast and reproducible protocol for Agrobacterium-mediated transformation of D. rotundata using axillary buds as explants, which provides a useful platform for future genetic engineering studies in this economically important crop.