Implications of epigenetic variation during nodal micropropagation for substantive equivalence analysis: case study Cassava (Manihot esculenta Crantz)
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Date
2014
Authors
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Publisher
Sokoine University of Agriculture
Abstract
Transgenic plants are rapidly being adopted in parts of the world as a result of increased food
demand due to growing population and decrease in agricultural production following dramatic
changes in environment. Transgenic crops are accepted for import for food and feeds use and
for release into the environment in different countries in the world. For vegetative propagated
plants, there is always a phytosanitary concern for international exchange of materials, which
require the use of tissue culture as a means to produce virus free plantlets that can then be
transported across international boundaries without presenting a quarantine hazard. Although in
vitro propagation systems that are based on the use of micro cuttings are widely viewed as
being analogous to field cuttings, much is not known about the possible epigenetic changes
induced by this type of micropropagation. In this study, we survey for epigenetic changes
during propagation by node culture and by field cuttings of five cassava (Manihot esculenta
Crantz) varieties. Genome-wide DNA methylation profiles revealed by Methylation Sensitive
Amplified Polymorphism (MSAP) uncovered consistent epigenetic differences between clonal
materials recovered from in vitro nodes and from those produced from stem cuttings. Also, the
observed epigenetic variance between different organs from the same plant was greater between
tissues from field grown plants than that observed between organs secured from in vitro
propagated plants. In this study we uncover differential methylation markers at several loci that
could be implicated at organ differentiation and maturation in cassava. We explore the
significance of these findings when seeking to predict potential effects to transgenic cassava
when imported in tissue culture form and its consequences to the crop physiology and
performance during field trials before it is proved substantially equivalent to their traditional
local isogenic comparators.
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Description
Dissertation
Keywords
Transgenic plants, Agricultural production, Food demand