Enhanced seed development in the interspecific cross Allium cepa x A. sphaerocephalon through ovary culture

Abstract

Allium sphaerocephalon pollen tubes grew into styles and penetrated micropyles of AUium cepa, but ovules started to degenerate about 16 days after pollination and no seeds developed. Seeds developed in vitro in ovaries excised from flowers 4 and 7 days after pollination. Seven weeks after culture initiation, seeds had grown in 4 of 96 excised ovaries, cultured on BDS medium supplemented with GA 3. Although the culture medium supported seed maturation within excised ovaries of self-pollinated A. cepa flowers, no viable hybrid seeds were recovered from crosses with A. sphaerocephalon. Extended post-fertilization barriers may have restrained development of hybrid embryos in vitro. Ovary culture followed by in ovulo embryo rescue may be feasible for distant-species hybridization in Allium.

Pre- and post-fertilization barriers to backcrossing the interspecific hybrid between Allium fistulosum L. and A. cepa L. with A. cepa

“…Therefore, only limited opportunity exists for fertilization and subsequent embryo and seed development . Similar descriptions of disturbed pollen tube growth affecting seed production in various interspecific crosses of Allium have been published by Saini & Davis (1967), Gonzalez & Ford-Lloyd (1987) and Bino et al . (1989) .…”

“…fistulosum) . We investigated whether less-laborious ovary and ovule culture techniques (Gonzalez & Ford-Lloyd, 1987 ;Bino et al ., 1989) could also result in an increase of the progeny of backcrosses from interspecific hybrids between A . cepa and A .…”

Meiotic Irregularities in Interspecific Crosses Within Edible Alliums

“…Alliums hybrid embryos were usually cultured on a phytohormonefree medium (Amagai et al, 1995;Gonzalez & Ford-Lloyd, 1987;Nomura & Makara, 1993;Umehara et al, 2006). Whole ovary culture supported maturation of viable seeds in hybrids of A. cepa x A. sphaerocephalon (Bino et al, 1989) or A. fistulosum x A. schoenoprasum (Umehara et al, 2007). Keller et al (1996) adopted ovary culture and obtained many hybrids between onion and other distant species.…”