Self-incompatibility in species ofLycopersiconSect.Eriopersiconand hybrids withL. esculentum

All tested plants of 11 accessions of the typical form of Lycopersicon peruvianum and 11 of its variety dentatum were found to be self-incompatible. Reactions tested extensively in one collection conformed exactly to the Nicotiana scheme. In addition, the other available species of the green-fruited subgenus Eriopersicon—L. peruvianum var. humifusum, L. glandulosum, and L. hirsutum—are self-incompatible, the reaction in the three species seeming to be as strong in their native habitat as in cultures in California. The species of the red-fruited subgenus Eulycopersicon are self-fertile, as is also L. hirsutum f. glabratum. Although the barrier to incompatible pollinations in L. peruvianum is very severe, a few seeds may be produced from incompatible matings by plants of slightly reduced vigor. All attempts to induce pseudo-fertility by means of various treatments failed. Hybrids of L. esculentum and L. peruvianum are as highly self-incompatible as the latter parent, but matings between hybrids of different parentage are highly compatible. As pistillate parents, these hybrids cross readily with L. peruvianum but not with L. esculentum, but as staminate parents they mate successfully with L. esculentum but not with L. peruvianum. With a few exceptions the same mating relations were found between the F2 and the parental species. These compatibilities can be explained if it is assumed that the S oppositional factors act in the Fj and F, hybrids in the same fashion as in L. peruvianum, but also oppose pollen bearing se, a recessive fertility allele from L. esculentum.