Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/1999
Publication Date: N/A
Interpretive Summary: The old and time-consuming method for making inbred broccoli varieties is to self-pollinate plants for several generations. A newer and less time-consuming approach is to use tissue culture techniques, that result in inbreds in just a single generation. There are two basic tissue culture methods for rapid inbred production. With one method, called anther culture, anthers are extracted from flowers and grown on a special media. After a month or so, immature pollen inside the anther develop into embryos and finally plants. With the other method, called microspore culture, immature pollen are extracted from flowers, cultured independent of anthers, and embryos develop directly from these cultured pollen. There are advantages and disadvantages to using one method or the others. The purpose of this research was to determine if one of the techniques is better than the other. Our results showed that success with either method may depend on the characteristics of the parent plant one uses as a source of anthers or immature pollen. However, on average, the two methods are similarly efficient at producing embryos and plants, and the qualities of plants resulting from both methods are similar. This research provides public and private broccoli breeders with useful information to help them breed improved, high quality varieties. Ultimately, those better varieties will enhance production and provide a stable supply of quality broccoli for consumers.
Technical Abstract: The use of microspore or anther culture to generate doubled-haploid (DH) lines for use as parents for hybrid production is an important adjunct to breeding broccoli. It has been documented that regenerants from anther culture can be haploids, diploids, triploids, tetraploids, octaploids, or aneuploids. However, populations derived from microspore culture have not been characterized for ploidy composition. Thus, the present study was undertaken to investigate characteristics of regenerants derived from microspore culture, evaluate factors influencing these characteristics, and compare results with those from anther culture. Eight populations, four from anther culture and four from microspore culture, were generated using four F1 hybrids as parents. Ploidy of regenerated plants, and also clonal families derived from both culture methods, were determined using DNA flow cytometry. Results showed that a majority of all populations were diploid. .As in anther culture, mixtures of ploidy were observed in all populations derived from microspore culture. Ploidy variation was more frequent among clonal families derived from anther culture (10%) than microspore culture (5%). 'Everest' was the most productive parent in anther and microspore cultures while 'Greenbelt' and 'Major' were the least in anther and microspore culture, respectively. Genotype specificity for total number of regenerated plants and ploidy composition occurred in both culture methods. In addition, interaction between genotype and culture methods appeared to affect the ploidy composition in regenerated populations. Although differences between culture methods have been identified, both methods can be used effectively for DH production.