Petunia hybrida CAROTENOID CLEAVAGE DIOXYGENASE7 Is Involved in the Production of Negative and Positive Branching Signals in Petunia

We report that the decreased apical dominance3 mutant of petunia results from the mutation of the PhCCD7 gene and has a less severe branching phenotype than mutation of PhCCD8

Revel S.M. Drummond; N. Marcela Martínez-Sánchez; Bart J. Janssen; Kerry R. Templeton; Joanne L. Simons; Brian D. Quinn; Sakuntala Karunairetnam; Kimberley C. Snowden

2009

Scholarcy highlights

  • One of the key factors that defines plant form is the regulation of when and where branches develop
  • We show that the regulation of PhCCD7 is similar to that of the PhCCD8 gene, with expression predominantly in root and stem tissue and up-regulation of expression in plants with increased numbers of branches
  • The mutant allele is likely to be null, introducing a stop codon after amino acid 155, whereas the full-length protein is 621 amino acids. This conclusion is supported by the observation that the phenotype of the RNA interference pattern overlaps, but is not identical to, that shown for PhCCD8 by Simons et al
  • We show that PhCCD7 has a lower level of expression than PhCCD8 and that PhCCD7 was detectable in more acropetal regions of stem tissue than PhCCD8
  • It is likely that only tissues where both PhCCD7 and PhCCD8 are expressed are important in the control of branching
  • As seen for PhCCD8, we show that PhCCD7 expression is altered in response to the branching phenotype of the scion, suggesting that regulation of expression of the CCD7 and CCD8 genes is under feedback control
  • A model that includes more than one biologically active molecule from this pathway will allow a more complete understanding of the developmental and environmental controls of plant form

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