DIRECT SHOOT REGENERATION FROM VACCINIUM-PAHALAE (OHELO) AND VACCINIUM-MYRTILLUS (BILBERRY) LEAF EXPLANTS

Ohelo (V. pahalae Skottsb.) and bilberry (V. myrtillus L.) shoots were regenerated via direct organogenesis from whole leaves and leaf secti ons and also from hypocotyl explants of bilberry. Explants preincubate d for 1 to 2 weeks in darkness yielded approximate to 75% regeneration frequencies and the highest number of regenerating shoots/explant on TDZ-supplemented media (0.9 to 2.7 mu M). When 2iP or zeatin were subs tituted as the cytokinin source, frequencies of regeneration and shoot productivity were significantly lower, Explants held under constant i llumination (no dark pretreatment) had significantly lower regeneratio n frequencies in all tested cytokinin-supplemented media. 2,4-D stimul ated callus formation, but did not support regeneration from vegetativ e explants. Cells from callus and suspension cultures did not exhibit regeneration in any of the media that supported organogenesis from lea ves. Regenerants were successfully micropropagated, although callus fo rmation caused by zeatin and high 2iP levels interfered with shoot pro liferation, Zeatin induced hyperhydricity in shoots from both species, but more severely in ohelo. Ex vitro rooting after treatment with 4.9 mu M IBA or 5.4 mu M NAA was 95% and 60% successful for bilberry and ohelo, respectively, and plants were readily acclimatized after an int erval in a fog chamber. Bilberry microshoots also rooted in vitro in t he absence of growth regulator treatment. Chemical names used: 1H-indo le-3-butanoic acid (IBA); N-(3-methyl-2-butenyl)-1-H-purine-6-amine (2 iP); 6-furfurylaminopurine (kinetin); 1-naphthaleneacetic acid (NAA); thidiazuron=1-phenyl-3-(1,2,3-thiadiazio-5-yl)urea (TDZ); 2,4-dichloro phenoxyacetic acid (2,4-D); 6-(4-hydroxy-3-methylbut-2-enylamino) puri ne(zeatin).