CYTOLOGICAL EVIDENCE FOR 4 NEW PRIMARY TRISOMICS IN SOYBEAN

Four new primary simple trisomics (2n - 41) of soybean [Glycine Max (L.) Merr.], representing chromosomes 2, 3, 10, and 14, were identified, for the first time by Pachytene chromosome analysis. The precise cytological identification was based on association of the extra chromosome in a frivalent configuration, chromosome length, arm ratio, and distribution of euchromatin and heterochromatin. Additionally, the extra chromosome present in Triplo 2 also was shown to be different from the one present in Triplo 4 and Triplo 5 by crosses between them and by subsequent cytological observation of chromosome pairing in the 2n = 42 chromosome F1 plants. Together with the four previously identified primary trisomics, eight of the possible 20 primary simple trisomics of soybean have been successfully identified cytologically.