3.1.1. BPP morphology
The bending characteristic of BPP that occurred underneath the
flower bud during rose development is shown in Fig. 1a. In addition
to the bending, fasciation was always observed in BPP (Fig. 1b).
Also, the bending was invariably accompanied by the abnormal
development of the sepals. In the regular pattern of sepal
development in roses, as was observed in all control stems, the
first and second sepals are bearded (i.e., exhibit bristle-like
appendages) on both sides, the fourth and fifth sepals are nonbearded,
and the third sepal is bearded only on one side (Fig. 2a,
normal flower). In the abnormal pattern observed in BPP flowers,
there was organ conversion of the first sepal to a leaf-like
(phylloid) structure (Fig. 2b–d), the second and third sepals were
bearded on both sides (Fig. 2c), and the fourth sepal was
occasionally half bearded (Fig. 2b). This pattern implies that the
conversion of the first sepal into a phylloid structure leads to a shift