AUTHOR=Nyaboga Evans , Tripathi Jaindra N. , Manoharan Rajesh , Tripathi Leena 

TITLE=Agrobacterium-mediated genetic transformation of yam (Dioscorea rotundata): an important tool for functional study of genes and crop improvement

JOURNAL=Frontiers in Plant Science

VOLUME=5

YEAR=2014

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2014.00463

DOI=10.3389/fpls.2014.00463

ISSN=1664-462X

ABSTRACT=<p>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 <italic>Agrobacterium</italic>-mediated transformation of yam (<italic>Dioscorea</italic> spp.) with evidence of stable integration of T-DNA. Yam is an important crop in the tropics and subtropics providing food security and income to over 300 million people. However, yam production remains constrained by increasing levels of field and storage pests and diseases. A major constraint to the development of biotechnological approaches for yam improvement has been the lack of an efficient and robust transformation and regeneration system. In this study, we developed an <italic>Agrobacterium</italic>-mediated transformation of <italic>Dioscorea rotundata</italic> using axillary buds as explants. Two cultivars of <italic>D. rotundata</italic> were transformed using <italic>Agrobacterium tumefaciens</italic> harboring the binary vectors containing selectable marker and reporter genes. After selection with appropriate concentrations of antibiotic, shoots were developed on shoot induction and elongation medium. The elongated antibiotic-resistant shoots were subsequently rooted on medium supplemented with selection agent. Successful transformation was confirmed by polymerase chain reaction, Southern blot analysis, and reporter genes assay. Expression of <italic>gusA</italic> gene in transgenic plants was also verified by reverse transcription polymerase chain reaction analysis. Transformation efficiency varied from 9.4 to 18.2% depending on the cultivars, selectable marker genes, and the <italic>Agrobacterium</italic> strain used for transformation. It took 3–4 months from <italic>Agro</italic>-infection to regeneration of complete transgenic plant. Here we report an efficient, fast and reproducible protocol for <italic>Agrobacterium</italic>-mediated transformation of <italic>D. rotundata</italic> using axillary buds as explants, which provides a useful platform for future genetic engineering studies in this economically important crop.</p>