Reduced GA biosynthesis in GmRAV-transgenic tobacco causes the dwarf phenotype

Resumo

GmRAV-transgenic tobacco plants exhibited decreased gibberellins (GAs) biosynthesis related phenotypes, including dwarfism and repressed flowering time. The dwarf phenotype of GmRAV-overexpressing (ox) tobaccos was fully restored in stem and hypocotyl length of transgenic plants by the application of exogenous GA₃. The epidermal cells in the stem internodes of the GmRAV-ox tobacco plants treated with GA₃ were obviously the same as those in wild-type plants in longitudinal direction. Therefore, the rescued plant height of GmRAV-ox tobaccos by GA₃ might be largely caused by increased cell size. GmRAV overexpression inhibited GA biosynthesis due to a transcriptional repression of GA20ox gene. The dwarfed phenotype of GmRAV-ox tobaccos with reduced stem elongation could be caused by a reduction in GA₃ content.