THE INHERITANCE OF SELF-INCOMPATIBILITY IN HYBRIDS OF LYCOPERSICON ESCULENTUM MILL. x L. CHILENSE DUN

Abstract

SUMMARY Evidence was collected indicating that the self-incompatibility in L. chilense is of the Nicotiana type. The inheritance of self-incompatibility in hybrids of L. esculentum and L. chilense was studied in F,, F,, and backcross hybrids. Self-incompatibility ap- pears to be controlled by two or more dominant genes of major action in the hybrids. A difference in L. esculentum stocks with respect to these genes was found. Unilateral interspecific incompatibility was shown to have the same genetic control in these materials as self-incompatibility. In addition, evidence was found of a polygenic difference between the two species affecting the strength of the incompatibility reaction. A polygenic barrier was shown to underlay the barrier due to the S genes. This resulted in poor pollen germination and extreme embryo abortion. A necrotic condition acting as a physiological breakdown was found among the hybrids. Self-incompatibility was found to be associated by linkage to three genes on chromosome two and several quantitative traits. A tentative linkage map of tomato chromosome two was constructed. Self-incompatibility was transferred from L. chilense to the L. esculentum variety Tiny Tim by six backcrosses.