Clonal breakdown

B.J.M. Zonneveld
Wed, 22 Nov 2006 00:55:02 PST
Clonal breakdown 
Plants grown from seed reset the genetic program so to speak. All bad
pieces are trown out directly or in the embryo stage etc In clonal
propagation and especially in TC this does not happen and like everywere
mutations slowly accumulate to such an extent that at a certain stage it
becomes visible. It is convenient to call such a happening a sport A
sport is a shoot deviating from the mother plant irrespective of the
cause. This means slowing down growth or changing flower colour or any
other character. This is especially visible in chimeras or variegated
plants Here a change can be due to 1. a chimeral rearrangement,an
exchange of layers ( a yellow edged plant gets a yellow centre or a
plain green or yellow shoot) or 2. due to mitotic recombination, an
exchange of parts of chromosomes ( A heterozygous yellow edge becomes
white) and 3. rarely due to a mutation, a change in DNA ( a green plant
gets a yellow edge)And of course viruses etc can be the cause too even
when not visible in the leaf or when they cannot be traced.Actually most
mutations are due to jumping retroviruses or transposable elements

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