Molecular analysis, cytogenetics and fertility of introgression lines from transgenic wheat to Aegilops cylindrica Host

Natural hybridization and backcrossing between Aegilops cylindrica and Triticum aestivum can lead to introgression of wheat DNA into the wild species. Hybrids between Ae. cylindrica and wheat lines bearing herbicide (bar), reporter (gus), fungal disease resistance (kp4), and increased insect tolerance (gna) transgenes were produced by pollination of emasculated Ae. cylindrica plants. F1 hybrids were backcrossed to Ae. cylindrica under open pollination conditions, and first backcrosses were selfed using pollen bags. Female fertility of F1 ranged from 0.03% to 0.6%. Eighteen percent of the sown BC1s germinated and flowered. Chromosome numbers ranged from 30 to 84 and several of the plants beared wheat-specific sequence characterized amplified regions (SCARs) and the bar gene. Self-fertility in two BC1 plants was 0.16% and 5.21%, the others were completely self-sterile. Among 19 BC1S1 individuals one plant was transgenic, had 43 chromosomes, contained the bar gene and survived glufosinate treatments. The other BC1S1 plants had between 28 and 31 chromosomes, several of them carried SCARs specific to wheat A and D genomes. Fertility of these plants was higher under open pollination conditions than by selfing and did not necessarily correlate with even or euploid chromosome number. Some individuals having supernumerary wheat chromosomes recovered full fertility.

Key Words: SCARs, gene flow, hybridization, risk assessment, transgenic wheat

Online ISS 1091-6490
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