Genetic relationship between Echinochloa crus‐galli and Echinochloa oryzicola accessions inferred from internal transcribed spacer and chloroplast DNA sequences

Barnyardgrass, hexaploid Echinochloa crus‐galli , is considered to arise from the hybridization between tetraploid Echinochloa oryzicola and an unknown diploid species. The genetic relationship between E . crus‐galli and E . oryzicola was examined to investigate the position of E . oryzicola in the evolutionary process of E . crus‐galli , based on the nuclear DNA internal transcribed spacer (ITS) and the chloroplast cpDNA trn T‐L, trn L intron, and trn L‐F regions. New World E . crus‐galli was clearly separated from Eurasian E . crus‐galli and showed a close relationship to the American taxa, Echinochloa crus‐pavonis and Echinochloa walteri, in both the ITS and chloroplast DNA. The nrDNA ITS sequences indicated no differentiation between the Eurasian E . crus‐galli and E . oryzicola , in contrast to their clear divergence in the cpDNA sequence. The present results suggest that E . oryzicola is the male donor of E . crus‐galli .