OPPOSITIONAL ALLELES CAUSING CROSS-INCOMPATIBILITY IN TRIFOLIUM REPENS

Abstract

N SEVERAL species in which cross-incompatibility is determined by I multiple oppositional alleles, different types of tests have shown that these series of alleles are very extensive. The test yielding the most decisive results and involving the fewest crosses consists of making all possible reciprocal combinations (that is, diallel crosses) between plants which have one S factor in common. This procedure was applied first by A similar test has since been made by WILLIAMS (1937) using red clover, in which 34 out of 40 alleles proved to be different. More recently, WILLIAMS (1941) reported on two other series of red clover plants in which 41 out of 48 and 37 out of 40 alleles, respectively, were different. Likewise, EMERSON (1940) has identified 45 different alleles in Oenothera organensis .