XVI International Botanical Congess

Mitotic chromosomes of sweetpotato, Ipomoea batatas (L.) Lam., were characterized by genomic in situ hybridization using digoxigenin labeled genomic DNA from I. trifida (HBK) G.Don, I triloba L. or I. lacunosa L. as a probe. FITC detection of the probe DNA showed several sweetpotato chromosomes with strong hybridization signals by both I. trifida and I. triloba, but not I. lacunosa. When the I. triloba probe DNA was mixed with unlabeled I. trifida DNA with 1:5-20 ratios in hybridization and the hybridized probe was detected by sensitive colormetric reactions by an enzyme conjugated antibody, approximately one third of the chromosomes deposited color. When I. trifida DNA was a probe with I. triloba blocking DNA, two thirds deposited color. The sweetpotato genome may consist of those closely related to I. trifida and I. triloba.