Through tissue culture lab techniques, we have produced hundreds of doubled haploid (DH) plants derived from important lines (yellow, red, pungent, mild) under development in the onion breeding program. Many of these "instant inbred" DH plants, which were initially generated in 2003, were grown in the field in Ithaca in the summer of 2006. Sufficient seeds were available from the previous years` field work to allow a substantial replicated field trial of DH lines this year. Some of these lines were as vigorous and producd bulbs as large as ones from moderately inbred conventional population, rather than being extremely small as might be expected for highly material. These lines could allow release of uniform new lines with improved yield or resistance to pests many years sooner than possible by standard methods. They are also proving to be useful for studies of onion genomics.

Development of improved onion varieties by conventional breeding is a very slow process because onion is a biennial crop. Doubled haploid (DH) plants, obtained via tissue culture techniques, are equivalent to inbred lines but can be produced within 1-2 years. Thus DH techniques may cut up to eight years from the time usually required to develop uniform improved onion inbreds for applied use. Quality or pest-resistance traits controlled by multiple genes are particularly hard to stabilize by standard approaches. This project, a collaboration between the Earle tissue culture lab and the Mutschler onion breeding program, has produced hundreds of DH plants from diverse onion breeding lines and has recovered seed from many of them. Some of these lines are likely to be of importance to the breeding effort. Our work will speed development of improved onion lines for NYS producers. It is also generating information that will be of value to onion breeders elsewhere in the U.S. and worldwide.

We have cultured thousands of immature unpollinated flower buds from many different onion lines and have regenerated plants from most of these lines. Reliable techniques for determining whether the regenerated plants are haploid or diploid have been developed. Procedures for inducing chromosome doubling of haploids have been compared and improved, making it more efficient to convert haploids into fertile DH plants. Hundreds of DH plants have been transferred out of culture into soil and provided to the onion breeding program. The breeding program has conducted three years of field tests and has collected substantial data on bulb size, pollen fertility, seed set, etc. We believe that we have done more extensive field tests of onion DH than any other group. The information in hand will allow us to correlate the field results with the lab treatments used and will help guide further work. The progress made to date should speed development of improved onion varieties for use in hybrid production or as open pollinated lines. Frequent reports to New York onion research organizations have been provided to New York state onion groups and to vegetable breeding companies. We have also provided materials from the program to an onion genomics program in New Zealand.

This project illustrates how Cornell cell biologists work together with applied breeders to help New York state agriculture. Economic impact is yet to come but the specific goal is to keep New York onion growers competitive by providing them with high-quality breeding lines addressing current market factors. Several substantial peer-reviewed research papers have also been published.

Ali Alan (previously here) (University of Ottawa)