  We discuss how unification of the gauge, Higgs and (three chiral family)
matter superfields can be realized from the compactification of a six
dimensional supersymmetric SU(8) gauge theory over the orbifold R^4 x T^2/Z_3.
The bulk gauge interaction includes Yukawa interactions to generate masses for
quarks and leptons after the electroweak symmetry is broken. The Yukawa
matrices in this case turn out to be antisymmetric, and thus not
phenomenologically viable. To overcome this we introduce brane fields which are
vector-like under the standard model gauge symmetry, and so do not alter the
number of chiral families. In such a setup, the observed fermion masses and
mixings can be realized by taking into account suppression effects from the
effective Wilson line couplings and large volume of the extra dimensions.
