POLYPLOID BREEDING AND THE POTENTIAL OF ITS USE FOR TRANSGENE CONTAINMENT WITH AMERICAN CRANBERRY (VACCINIUM MACROCARPON)

The American cranberry has received limited genetic improvement over wild selections.
We are using multiple approaches in the improvement of cranberry, including conventional breeding which has resulted in the release of a high fruit color selection, ‘HyRed’, and transgenic breeding to incorporate herbicide tolerance.
We are also investigating polyploid breeding because of a potential yield increase due to enhanced flower bud set and fruit size.
In addition, polyploids may offer a mechanism to restrict transfer of introduced genes to conventional plantings or wild populations through a triploid block.
Fertility was a problem with colchicine-induced polyploids, but crosses among these have produced selections with greatly improved fertility (exceeding 80% fruit set in greenhouse tests). It would be desirable to bring traits such as high fruit color or herbicide tolerance from the diploid to the polyploid level without the need for colchicine treatment and the associated fertility problems.
In particular, we have greatly enhanced the tolerance to glufosinate-based herbicides when a bar-transformant of ‘Pilgrim’ was crossed to ‘HyRed’. Selected progeny were tolerant up to 8000 ppm, compared to 500 ppm for the original transformant.
However, no elevation in herbicide tolerance level was observed in progeny of the analogous cross between colchiploids of ‘HyRed’ and bar-‘Pilgrim’, although the tolerance was inherited in the expected proportion.
The use of 2n pollen, readily identifiable in Vaccinium species as dyads, may be another method to move traits to the polyploid level.
We have observed dyads in all samples of cranberry pollen and a survey of dyad concentrations in the field found a range of 1 to 5% among seven cultivars.
When a polyploid selection was pollinated with pollen from diploid ‘HyRed’, fruit and seed set were greatly reduced; however some viable seeds were recovered, possibly the result of 2n pollen.
The potential of polyploids for transgene containment is discussed.

XI Eucarpia Symposium on Fruit Breeding and Genetics

E.L. Zeldin, B.H. McCown

: colchicine, fertility, fruit set, bar gene, glufosinate, transgene containment, 2n pollen

https://doi.org/10.17660/ActaHortic.2004.663.151