Overexpression of NlgCycB Isolated from Interspecific Hybrid of N. langsdorffii × N. glauca Alters Root Growth and Root Hair Development

A cDNA clone encoding cyclin B ( NlgCycB ) was isolated from an interspecific hybrid of N. langsdorffii × N. glauca . The full-length cDNA had an open reading frame of 1,422 bp, with a deduced amino acid sequence of 473 residues. To investigate the role of NlgCycB , transgenic tobacco plants were constructed to overexpress NlgCycB . The transgenic plants showed premature root hair development in the elongation zone of the root tips. They had more and longer root hairs, which contained nuclei of increased size. Flow cytometric analysis revealed that the proportion of cells with 4C DNA content was increased in the transgenic plants. The NlgCycB gene in transgenic plants was coordinately enhanced with the expression of CDKA genes, especially in the root tips. The transgenic plants had greater growth than the wild-type in MS (1/10-strength) medium with reduced salt concentrations. Taken together, NlgCycB may play an important role in premature root hair development in the elongation zone of root tips and can aid in adaptation to low nutrient salt environments.