FIGURE 1.

Petunia species, varieties, and growth characteristics. (A) Petunia is world-wide one of the most popular bedding plants, nowadays frequently used also in hanging baskets for city decoration (Vienne, France). (B,C) Petunia axillaris and P. inflata are two wild species native to South America with contrasting flower architecture, pigmentation, and pollination syndromes (Stuurman et al., 2004). From the early 19th century onward, these two species [or closely related (sub)species thereof] were used as parents in interspecific crosses, providing the genetic material for modern P. hybrida cultivars (Stehmann et al., 2009; Segatto et al., 2014). (D–F) Most popular petunia varieties used in research. Mitchell and V26 are easily transformable lines; W138 is the high-copy number dTPH1 transposon line, used in transposon mutagenesis. (G,H) The compact growth habit of the W138 variety allows high-density cultivation in tray systems until flowering. (G) Young plants; (H) Flowering plants; one individual has been sorted from the tray, showing the turfcontainers facilitating plant transfer. (I) A single petunia anther fotographed next to an Arabidopsis flower illustrates the large size of petunia floral organs. (J) Petunia produces dry fruits, each containing ∼60–200 seeds (opened seedpod). Photo credits: (B) Peter von Ballmoos; (C) Katrin Hermann.