A micropropagation procedure was developed to regenerate plants via tissue culture from explants of harvested and stored French endive (Cichorium intybus L. Witloof). The procedure permits the rescue of French endive germplasm that shows resistance to postharvest physiological disorders and diseases. The procedure was used successfully to regenerate plants which showed resistance to different undesirable marketable traits.. Under a long day photoperiod, a high percentage of the explants produced flowers in vitro. Thidiozuron was used successfully to regenerate plants from small leaf explants.
Yasseen Mohamed-Yasseen and Walter E. Splittstoesser
Yasseen Mohamed-Yasseen, Walter E. Splittstoesser, and Richard E. Litz
Renee M. Schloupt, Walter E. Splittstoesser, and Robert M. Skirvin
The objective of this research was to induce vitrification in onion (Allium cepa L. cv. `White Ebeneezer'); then use this information to make suggestions on how to avoid vitrification of micropropagated plants. There were no differences in vitrification percentage when shoot tip explants were isolated, sterilized and placed on MS medium (8 g.L-1 agar) supplemented with 0.16 uM NAA and varying (0.0 to 70.0 uM) levels of BA. When agar was replaced by gelrite (MS medium with 4.4 uM BA and 0.16 uM NAA), vitrification increased when gelrite concentrations decreased from 2.0 to 1.0 g.L-1. More vitrification occurred when shoot tips were supported on a synthetic cosmetic puff in liquid medium or when agar was reduced to 4.0 g.L-1 than when supported on a cosmetic puff in 8 g.L-1 agar or on 8 g.L-1 agar alone.
Nawab Ali, Robert Skirvin, Walter E. Splittstoesser, and William L. George
Cucumber (Cucumis sativus L.) seeds of `Marketer', `Marketmore', `Wisconsin SMR-18', `Tablegreen', `Spotfree', and `China' were stored at 3C and 38% relative humidity for up to 26 years. Seed older than 13 years did not germinate. Cultivars stored 10 years gave 80% germination, except Wisconsin SMR-18' (40%). Ten-year-old seeds were separated from their seedcoats, and cotyledons were excised into six segments. Explants were placed on Murashige and Skoog medium with all combinations of BAP (0, 1,2, and 3 mg·liter-1) and NAA (0, 0.1,0.2, and 0.3 mg·liter-1). Plants were obtained from culture for all cultivars grown on medium containing NAA and 1 mg BAP/liter. No plants were regenerated when BAP or NAA was lacking. Chemical names used: benzylaminopurine (BAP), 1-naphthaleneacetic acid (NAA).
Nawab Ali, Robert M. Skirvin, and Walter E. Splittstoesser
Walter E. Splittstoesser, Ellen B. Rest, and Cleora J. D'Arcy
Nawab Ali, Robert M. Skirvin, Walter E. Splittstoesser, David E. Harry, and William L. George
Seed lots with the genetic background of `Baroda' and `Marketer' cucumber (Cucumis sativus L.) containing all possible combinations (DF Df, Dfdf, dfdf) of df (which increases dormancy) and Df (wild type) were used. Dormancy was not solely due to the genotype dfdf and clear effects of genetic background were apparent. The df allele in the homozygous state induced a strong dormancy in `Baroda', but the Df gene could not restore normal germination. However, Df did reduce the dormancy period to 85 days. In `Marketer', df did not delay germination. Any treatment (puncturing, removal, cutting) that damaged the inner integument allowed `Baroda' dfdf to germinate, indicating an intact integument was essential for maintaining dormancy in this cultivar. All `Baroda' dfdf embryonic axes without the cotyledons germinated in 5 days. `Baroda' dfdf seeds with intact integuments imbibed adequate water to germinate but remained dormant, suggesting that the effect of the integument on dormancy was not related to imbibition.