Complementary gene interaction and xenia effect controls the seed coat colour in interspecific cross between Trifolium alexandrinum and T. apertum.

Trifolium alexandrinum (Egyptian clover) is a widely cultivated winter annual fodder. Present work deals with inheritance of the seed coat colour in segregating progenies of the interspecific cross between T. alexandrinum and T. apertum. Although, both the parent species possessed yellow seed coat, the F seeds were black coloured in the reciprocal cross (T. apertum × T. alexandrinum). Seeds borne on individual F plants and the advancing generations segregated in yellow and black seed coat colour, which confirmed xenia effect. F seeds collected from individual F plants exhibited nine black and seven yellow segregation ratio. The segregation of the seed coat colour recorded from F to F generations revealed that yellow seed coat was true breeding (i.e. non-segregating) in this interspecific cross (including the reciprocal crosses). However, the black seeded progenies were either true breeding or segregated in nine black: seven yellow ratio or three black: one yellow ratio suggesting a complementary gene interaction or duplicate recessive epistasis. It indicated that the seed coat colour is controlled by complementary gene interaction along with xenia effect in interspecific crosses between T. alexandrinum and T. apertum. Occurrence of the complementary genes across the species could suggest T. apertum to be the progenitor of T. alexandrinum. Inheritance of seed coat colour in reference to its importance in Egyptian clover breeding is also discussed.