  One loop corrections to the helicity amplitudes of all 2 -> 2 subprocesses
are calculated in QCD and in N=1 supersymmetric Yang-Mills theory using two
versions of dimensional regularization: the `t~Hooft-Veltman scheme and
dimensional reduction. Studying the structure of the soft and collinear
singularities, we found universal transition rules for the squared matrix
element which can be used to translate the results obtained in these schemes to
the results valid in the conventional dimensional regularization scheme. With
explicit calculation it is demonstrated that the one loop helicity amplitudes
of the 2 -> 2 subprocesses calculated using dimensional reduction in the N=1
supersymmetric $SU(N)$ gauge theory respect the supersymmetry Ward identities.
Our transition rules can also be used to calculate the next-to-leading order
Altarelli-Parisi kernels in the dimensional reduction scheme when they satisfy
supersymmetry Ward identities as well.
