  In this paper, we consider a possible representation of a DNA sequence in a
quaternary tree, in which on can visualize repetitions of subwords. The
CGR-tree turns a sequence of letters into a digital search tree (DST), obtained
from the suffixes of the reversed sequence. Several results are known
concerning the height and the insertion depth for DST built from i.i.d.
successive sequences. Here, the successive inserted wors are strongly
dependent. We give the asymptotic behaviour of the insertion depth and of the
length of branches for the CGR-tree obtained from the suffixes of reversed
i.i.d. or Markovian sequence. This behaviour turns out to be at first order the
same one as in the case of independent words. As a by-product, asymptotic
results on the length of longest runs in a Markovian sequence are obtained.
