  For a graph $G$, the tree graph ${\cal T}_{G,t}$ has all tree subgraphs of
$G$ with $t$ vertices as vertex set and two tree subgraphs are neighbors if
they are edge-disjoint. Also, the $r^{th}$ cut number of $G$ is the minimum
number of edges between parts of a partition of vertex set of $G$ into two
parts such that each part has size at least $r$. We show that if $t=(1-o(1))n$
and $n$ is large enough, then for any dense graph $G$ with $n$ vertices, the
chromatic number of the tree graph ${\cal T}_{G,t}$ is equal to the
$(n-t+1)^{th}$ cut number of $G$. In particular, as a consequence, we prove
that if $n$ is large enough and $G$ is a dense graph, then the chromatic number
of the spanning tree graph ${\cal T}_{G,n}$ is equal to the size of the minimum
cut of $G$. The proof method is based on alternating Tur\'an number inspired by
Tucker's lemma, an equivalent combinatorial version of the Borsuk-Ulam theorem.
