Efficient Micropropagation of Chestnut Hybrids(Castanea spp.)Using Modified Woody Plant Medium and Zeatin Riboside

The chestnuts genus(Castanea spp.)is comprised of economically important trees native to the Northern hemisphere that are used as food and hardwood timber.Here,a very efficient method for micropropagation of European×Japanese chestnut hybrids(Castanea sativa×C.crenata)is described.Woody Plant Medium was used as the basal medium.In vitro shoots of four rootstock cultivars were micropropagated without shoot-tip necrosis on multiplication medium containing 5.7 or 11.4μmol·L^(−1)zeatin riboside,and were rooted on rooting medium containing 2.46μmol·L^(−1)indolebutyric acid.Monthly shootmultiplication rates for each cultivarwere 2–5 folds.In vitro rooting percentages for four cultivars were 87%for‘Maraval’,67%for‘Marigoule’,93%for‘Marsol’,and 97%for‘Précoce Migoule’.Within a 5 week period,80%–95%of rooted shoots were successfully acclimated under high humidity conditions after they were planted in either soil or rockwool.

Agrobacterium tumefaciens-Mediated Transformation of Wild Tobacco Species Nicotiana debneyi, Nicotiana clevelandii, and Nicotiana glutinosa

Studies on Agrobacterium tumefaciens-mediated transformation of wild tobaccos Nicotiana debneyi, Nicotiana clevelandii, and Nicotiana glutinosa were conducted. Leaf disks were infected and co-cultivated with A. tumefaciens strain EHA105 carrying the binary vector pBISN1 with an intron interrupted β-glucuronidase (GUS) reporter gene (gusA) and the neomycin phosphotransferase gene (nptII). Selection and regeneration of kanamycin resistant shoots were conducted on regeneration medium containing 8.88 μM 6-benzylaminopurine (BAP), 0.57 μM indole-3-acetic acid (IAA), 50 mg·L-1 kanamycin and 250 mg·L-1 timentin. Kanamycin resistant shoots were rooted Murashige and Skoog (MS) medium containing 100 mg·L-1 kanamycin and 250 mg·L-1 timentin. Using this protocol, kanamycin-resistant plants were obtained from all three wild tobaccos at frequencies of 75.6% for N. debneyi, 25.0% for N. clevelandii, and 2.8% for N. glutinosa. Transcripts of nptII and gusA were detected in kanamycin-resistant T0 transformants (i.e., 2 for N. glutinosa and 5 for each of the N. debneyi and N. clevelandii) by the reverse transcript polymerase chain reaction (RT-PCR), and histochemical GUS assays confirmed expression of gusA in both T0 plants and T1 seedlings. The results indicate that the protocols are efficient for transformation of wild tobacco N. debneyi and N. clevelandii.