Polyembryony in Soybeans1

Twin seedlings were observed in the progeny of malesterile (ms1ms1) plants of Glycine max (L.) Merrill from natural crossing blocks. Of the seedlings observed, more than 4% were embryonic twins. Triplets and conjoined individuals were also found. Cytological examinations of root‐tip preparations revealed that most individual plants from twin sets were diploid (2n=40). However, diploid: haploid and diploid:triploid twin pairs were also identified. Genetic analysis of a marker trait in the twin seedlings and their selfed progeny indicated that diploid diploid sets originated primarily after cross‐fertilization. Evidence suggests that the mechanism underlying the development of these twins involves a cleavage of the zygote or the development and fertilization of multiple embryo sacs within an ovule.