Development of transgenic triticale as a platform for novel bio-industrial
products is predicated on an environmental biosafety assessment that
quantifies the potential risks associated with its release. Pollen-mediated
gene flow to related species and conventional triticale varieties is one
pathway for transgene movement. A tier 1 quantification of triticale
hybridization was conducted by emasculating and hand pollinating flowers
under greenhouse conditions. Approximately 2000 manual pollinations were
conducted for each cross and its reciprocal between two triticale genotypes:
a modern triticale cultivar (AC Alta) and primary triticale (89TT108), and
common wheat, durum wheat and rye. The frequency of outcrossing, hybrid seed
appearance and weight, and F1 emergence and fertility were recorded.
Outcrossing, F1 emergence and fertility rates were high from crosses
between triticale genotypes. Outcrossing in inter-specific crosses was
influenced by the species, and the genotype and gender of the triticale
parent. In crosses to common and durum wheat where triticale was the male
parent, outcrossing was ≥73.0% and ≥69.5%, respectively, but ≤23.9% and ≤3.0% when triticale was the female parent. Overall, outcrossing with
rye was lower than with common and durum wheat. F1 hybrid emergence was
greater when triticale was the female parent. With the exception of a single
seed, all wheat-triticale F1 hybrid seeds were non-viable when
triticale was the male parent in the cross. Only seven durum wheat-triticale
F1 hybrids emerged from 163 seeds sown, and all were produced with
triticale 89TT108 as female parent. With rye, 8 F1 hybrids emerged from
38 seeds sown, and all were produced from crosses to AC Alta; five with AC
Alta as the female parent and three as the male. Interspecific F1
hybrids were self-sterile, with the exception of those produced in crosses
between common wheat and triticale where triticale was the female parent.
Tier 2 hybridization quantification will be conducted under field
conditions.