Self-compatibility in Lolium temulentum L: its genetic control and transfer into L. perenne L. and L. multiflorum Lam

The segregation of self-compatibility from L. temulentum was examined in backcross generations derived from hybrids between this species and the self-incompatible species, L. perenne and L. multiflorum, the latter being used as recurrent parents. Segregation patterns for self-compatibility were determined by percentage self seed set and by in-vitro self-pollination scores in the resulting backcross generations. Self-compatibility in L. temulentum is controlled in a gametophytic manner by a single gene mutation of either the Z locus or a locus tightly linked to it. Self-compatibility can be fixed in the homozygous form (i.e. 100 per cent pollen-tube growth on selfed stigmas) by selfing half compatible backcross plants. The S locus is still present in L. temulentum and functions when combined with a functional Z locus derived from either L. perenne or L. multiflorum. This has evolutionary significance for the relationship of the self-compatible and -incompatible Lolium species.