Abstract: Two S 18 elite lines that were selected from a novel F₁ hybrid plant between rice and a perennial wild grass Zizania latifolia (Griseb.) Turcz. ex Stapf exhibited several desirable traits characteristic of the wild donor species Z. latifolia. However, direct evidence for introgression was lacking. The present study was aimed to characterize these two lines by molecular analysis. Genomic DNA of the two lines and of their rice and Z. latifolia parents were isolated and digested with two restriction enzymes. The blots were then probed with 10 diagnostic, low-copy or moderate-repetitive sequences cloned from genomic DNA of Z. latifolia. It was found that RFLP patterns of the two lines were identical in all the 20 probe/enzyme combinations. In 18 combinations, the two lines were also identical with their rice parental cultivar Matsumae. In two probes, however, the two lines differed distinctively from Matsumae, with hybridization fragment(s) apparently from the wild donor species, Z. latifolia. Meanwhile, loss of the rice parental fragment(s) was also observed with these two probes. Since the two lines were maintained by strict selfing, it was concluded that the changed RFLP patterns of the two lines were the result of Z. latifolia DNA introgression, followed by possible non-homologous recombination and/or sequence modification.

Key words: Rice, Z. latifolia, Introgression, RFLP analysis