Embryo rescue and plant regeneration following interspecific crosses in the genus Hylocereus (Cactaceae)

Abstract

The aim of this study was to develop an efficient methodology to rescue embryos following interspecific crosses in the genus Hylocereus. Crosses between the diploids Hylocereus polyrhizus and H. undatus in both directions were performed. Fertilized ovules carrying embryos at very early pro-embryonic stages were excised from ovaries 5 days after pollination (DAP) and placed on half-strength basal MS medium containing 680 lM glutamine, 0.55 lM a-naphthaleneacetic acid (NAA), 0.45 lM thidiazuron (TDZ) and various concentrations of sucrose. After 30 days in culture, ovules were isolated from the surrounding tissue and transferred to the same fresh medium. Significant differences were found between the main effects (cross and sucrose concentration) in ovule response, i.e., increased ovule size and callus formation. The best responses were obtained in the cross: H. polyrhizus 9 H. undatus; and sucrose concentration of 0.09 M. In terms of embryo conversion, polyembryony and number of regenerated plants, the highest responses were observed on the culture medium supplemented with 0.17 M sucrose in both interspecific crosses. All tested plants were found to be diploid by flow cytometric analyses. Fluorescent amplifiedfragment length polymorphism (fAFLP) confirmed the hybrid origin of the regenerated plants. This study reports on the success of a three-step embryo rescue procedure for Hylocereus species. The procedure developed here provides the means for producing plants from very-early embryo stage, thus expanding the prospects for vine-cactus breeding programs.

Transposons in Plant Speciation

“…Disruption of this regulation in reproductive tissues in hybrids and polyploids can threaten the viability of the newly formed species. Note that embryo abortion, a classical postzygotic reproductive barrier, is very common in interspecific crosses and can be bypassed by embryo rescue, namely by feeding the embryo in culture (Cisneros and Tel-Zur, 2010). This suggests that the embryo is viable, but that the endosperm is not functioning to nourish the embryo.…”

Microcomputer tomography (microCT) as a tool in Pinus tree breeding: pilot studies

“…However, pre-zygotic barriers (before fertilisation) can reduce the numbers of mature cones or seed harvested, while post-zygotic barriers (after fertilisation) can increase the number of hollow seeds without affecting the number of seed extracted from the cones (Critchfield and Kinloch 1986;Owens et al 1990). Therefore, estimating the time (in weeks) after pollination that fertilisation might occur can help to estimate viable seed set during interspecific hybridisation and make subsequent tissue-culture (embryo rescue and micropropagation) projects more effective (Cisneros and Tel-Zur 2010). Previous studies used radiography to determine whether mature seed can be viable (Bramlett et al 1977;Tigabu and Odén 2003).…”

Efficacy of Biotechnological Approaches to Raise Wide Sexual Hybrids

“…In a few crosses of legumes, hybrid embryos have been transplanted into the developing endosperm of compatible seeds (Sabja et al 1990 ), Lilium (Van Tuyl et al 1991 ), Eruca × Brassica hybrids (Agnihotri et al 1990a ), Brassica (Gundimeda et al 1992 ), Brassica napus × Raphanobrassica (Agnihotri et al 1990b ) Ovary slice culture Pollinated ovary, a few days after pollination, is transversely cut into slices and the slices along with attached ovules are cultured So far confi ned to Lilium (Kanoh et al 1988 ;Van Tuyl et al 1991 ;Janson et al 1993 ;Obata et al 2000 ) Ovule culture Ovules are excised from pollinated ovaries before the initiation of embryo degeneration and cultured. In some crosses, cultured ovules are re-cultured on a different medium Alstroemeria (Bridges et al 1989 ;De Jeu et al 1992 ), Cyclamen (Ishizaka and Uematsu 1992 ), Nicotiana (Reed and Collins 1978 ;Iwai et al 1986 ), Lilium (Ikeda et al 2003 ), Gentiana (Morgan 2004 ), Hylocereus (Cisneros and Tel-Zur 2010 ), Asteraceae species (Wang et al 2014 ) Embryo culture Embryo is dissected from fertilized ovules and cultured Allium (Nomura and Oosawa 1990 ), Lilium (Van Tuyl et al 1991 ), Solanum (Singsit and Hannaeman 1991 ), Gossypium (Mehetre and Aher 2004 ), Hylocereus (Sage et al 2010 ) Sequential culture Culture of pollinated ovary, followed by culture of ovules from cultured ovaries and fi nally culture of embryos from cultured ovules. The time gap between each varies.…”