INTERSPECIFIC CROSSES INVOLVING ALFALFA. III. MEDICAGO SATIVA L. × M. PROSTRATA JACQ

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Abstract
The crossability between the two species was almost unimpaired when M. sativa was used as the maternal parent. With M. prostrata as mother the seed set was low and the seeds were poorly developed. Differences in genomic constitution of the endosperms of the reciprocal crosses may be responsible for these deviating results. At the diploid level in F1 almost normal chromosome pairing was observed; in F2 monofactorial segregation for the factor for anthocyanin flower color was observed, segregation for pod shape indicated that more than two factors were involved for that character. At the tetraploid level in F2 segregation for anthocyanin color suggested that preferential chromosome pairing was taking place. The cross is considered a border case in speciation where genic differentiation of two taxa has already imposed slight reproductive isolation.