[en] A simplified Gursay-Gunaydin model in which a lepton and a colour quark are united in the Majorana quaternion field is considered. Direct formulation of the gauge principle in the framework of quaternions leads to the appearance of two vector gauge quaternion fields corresponding to the decomposition of the invariance group SO(4)=SO(3)xSO(3). The diagonal subgroup SO(3), the quaternian automorphism, group, is considered as the quark pseudocolour symmetry, and the corresponding gauge field is interpreted as the three-gluon-colour field. The other gauge field corresponds to lepton-quark transition and acquires a (large) finite mass under spontaneous breaking of SO(4)-gauge symmetry due to the scalar quaternion field