Abstract
Some F1 hybrid plants between three species of the Aegilops genus and different hexaploid wheat Triticum aestivum cultivars show certain self-fertility, with averages of F1 hybrids bearing F2 seeds of 8.17%, 5.12% and 48.14% for Aegilops biuncialis, Aegilops geniculata and Aegilops triuncialis respectively. In the Ae. triuncialis-wheat combination with ";Astral" wheat cultivar, the fertility was higher than that found in the other combinations. All the F2 seeds studied were spontaneous amphiploids (2n=10x=70). The present study evidences the possibility of spontaneous formation of amphiploids between these three Aegilops species and hexaploid wheat and discusses their relevance for gene transference. Future risk assessment of transgenic wheat cultivars needs to evaluate the importance of amphiploids as a bridge for transgene introgression and for gene escape to the wild.
Highlights
One of the concerns raised over the introduction of genetically modified crops is the stable transference of the transgenes to the wild relatives causing ecologically significant changes in fitness that could lead to increased weediness or invasiveness (Darmency, 1994), which constitutes an important basis for risk assessment studies
The objective of this paper is to report the production and frequency of spontaneous amphiploids in the selfprogenies of hybrids between hexaploid wheat T. aestivum and the Aegilops species Ae. biuncialis, Ae. geniculata and Ae. triuncialis
The plant material employed in the experiments was the F2 seed progeny produced by selfing of the F1 hybrids between the wheat wild relatives Ae. geniculata (2n=4x=28 chromosomes, genomic constitution MMUU), Ae. biuncialis (2n=4x=28 chromosomes, UUMM) and Ae triuncialis (UUCC), and the T. aestivum (2n=6x=42, AABBDD) cultivars ‘Chinese Spring’ (CS), ‘Castan’ and ‘Astral’
Summary
One of the concerns raised over the introduction of genetically modified crops is the stable transference of the transgenes to the wild relatives causing ecologically significant changes in fitness that could lead to increased weediness or invasiveness (Darmency, 1994), which constitutes an important basis for risk assessment studies. Over the last decade much attention has been paid to crop to weed and wild hybridization as potential avenues for the escape of transgenes into natural populations. Prior to the commercialization of genetically modified crops the research on the natural hybridization between crops and related wild species was very limited. Most of the research was done with the purpose of breeding and with the aim of transferring desirable traits between species and crops were always used as female parent in Spontaneous wheat–Aegilops amphiploid production intergeneric and interspecific crosses. Gene flow between cultivated species and their weedy and wild relatives has been documented in species such as oilseed rape (Brassica napus L.) (Jørgensen and Andersen, 1994), maize (Zea mays L.) (Doebley, 1990), sorghum (Sorghum halepense (L.) Pers) (Arriola and Ellstrand, 1996), sunflower (Helianthus annuus L.) (Arias and Rieseberg, 1994) and sugarbeet (Beta vulgaris L.) (Bartsch and Pohl-Orf, 1996)
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