Soil salinity can be a limiting factor for productivity in agriculture and forestry. In order to fully utilize saline lands productively in plantation forestry for pulp production, the genetic modification of tree species for salttolerance may be required. The AhDREB1 gene, a DREBlike transcription factor gene, was transferred into Populus tomentosa by Agrobacterium-mediated transformation. Transgenic plants were regenerated and selected using a two-step process; first on Murashige and Skoog (MS) basal medium containing 4.44 lM 6-benzyladenine (BA), 1.61 lM a-naphthaleneacetic acid (NAA), 30 mg l -1 kanamycin, and 250 mg l -1 ceftomine, and then enhanced selection on medium with 50 mg l -1 kanamycin. The putative transformants were confirmed by polymerase chain reaction (PCR) and Southern hybridization for the AhDREB1 gene. Transgenic plants were rooted on halfstrength MS medium containing 5.71 lM indole-3-acetic acid (IAA), 1.61 lM NAA, 2 g l -1 sucrose, and 5 g l -1 agar. The salt tolerance of transgenic plants in pots in the greenhouse showed a survival rate of 100, 100, 84.4, and 44.4% after watering with a solution of 34.2, 68.4, 102.7, and 136.9 mM NaCl, respectively.
A genetic transformation protocol for green ash (Fraxinus pennsylvanica) hypocotyl explants was developed. Green ash hypocotyls were transformed using Agrobacterium tumefaciens strain EHA105 harboring binary vector pq35GR containing the neomycin phosphotransferase (nptII) and beta-glucuronidase (GUS) fusion gene, and an enhanced green fluorescent protein gene. Pre-cultured hypocotyl explants were transformed in the presence of 100 microM acetosyringone using 90 s sonication plus 10 min vacuum-infiltration. Kanamycin at 20 mg l(-1) was used for selecting transformed cells. Adventitious shoots regenerated on Murashige and Skoog medium supplemented with 13.3 microM 6-benzylaminopurine, 4.5 microM thidiazuron, 50 mg l(-1) adenine sulfate, and 10% coconut water. GUS- and polymerase chain reaction (PCR)-positive shoots from the cut ends of hypocotyls were produced via an intermediate callus stage. Presence of the GUS and nptII genes in GUS-positive shoots were confirmed by PCR and copy number of the nptII gene in PCR-positive shoots was determined by Southern blotting. Three transgenic plantlets were acclimatized to the greenhouse. This transformation and regeneration system using hypocotyls provides a foundation for Agrobacterium-mediated transformation of green ash. Studies are underway using a construct containing the Cry8Da protein of Bacillus thuringiensis for genetic transformation of green ash.
An AGAMOUS homolog (FpAG) was isolated from green ash (Fraxinus pennsylvanica) using a reverse transcriptase polymerase chain reaction method. Southern blot analysis indicated that FpAG was present as a singlecopy sequence in the genome of green ash. RNA accumulated in the reproductive tissues (female inflorescence, male inflorescence, and fruit) and vegetative tissues (leaves and in vitro-germinated seedlings). Expression was higher in reproductive tissues than in vegetative tissues. Ectopic expression of FpAG in transgenic Arabidopsis plants resulted in a range of weak to strong APETALA2 (AP2) mutant-like phenotypes, including early flowering, curly leaves, and conversion of petals to stamens. These data indicate functional homology between FpAG and AGAMOUS.
The chloroplast DNA (cpDNA) and mitochondrial DNA (mtDNA) of 16 Populus species (Section Leuce) and their F1 generation were detected using PCR-RFLP technique. The results show that cpDNA in the F1 generation of 22 hybrid combinations was inherited maternally, which supported the conclusions of the study of plasmid cytology. The mtDNA fragments amplifi ed by PCR were consistent with the restriction maps in all hybrid combinations and no polymorphism was detected, indicating that the Section Leuce is highly conserved in mitochondrial gene sequences. These results provided direct evidence of maternal chloroplast inheritance in Populus tomentosa, P. bolleana, P. davidiana, P. adenopoda, P. tomentosa × P. bolleana, P. alba × P. glandulosa and P. alba × P. tomentosa.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.