Variation of nuclear DNA content in interspecific Allium cepa L. x A. fistulosum L. hybrids and their successive backcross lines.

摘要

Interspecific hybrid plants between Allium cepa L. (2n=2X=16) and A. fistulosum L. (2n=2X=16) and their backcross lines were developed by artificial pollination in order to introduce new desirable characters of A. cepa to A. fistulosum. The 2C nuclear DNA content has been estimated by flow cytometry in 5 Allium fistulosum inbreed lines, 2 interspecific hybrid lines of A. cepa x A. fistulosum and 34 their backcross lines BC₁F₁ to BC₂F₂, using propidium iodide (PI) as a fluorescence dye. Estimated 2C DNA values ranged from 22.2 pg to 23.7 pg in 5 A. fistulosum inbreed lines, 37.9 pg in F1 hybrid between A. cepa and A. fistulosum, 24.3 pg to 27.3 pg in 7 backcross lines in BC₁F₁, 21.9 pg to 24.4 pg in 9 BC₁F₂, 22.9 pg to 25.1 pg in 14 BC₂F₁, 22.6 pg to 23.4 pg in 4 BC₂F₂. This study showed mean 2C nuclear DNA content of F₁ hybrid was higher than their backcross progeny lines, while it was lower than female parental line, A. cepa (2C DNA=33.2 pg). Mean 2C DNA content of backcross lines, BC₁F₁ to BC₂F₂ was not significantly different but their 2C DNA contents in the more progress generation from BC₁F₁ to BC₂F₂ were reduced.