Genetics and genomics of flower initiation and development in roses

Abstract

Roses hold high symbolic value and great cultural importance in different societies throughout human history. They are widely used as garden ornamental plants, as cut flowers, and for the production of essential oils for the perfume and cosmetic industries. Domestication of roses has a long and complex history, and the rose species have been hybridized across vast geographic areas such as Europe, Asia, and the Middle East. The domestication processes selected several flower characters affecting floral quality, such as recurrent flowering, double flowers, petal colours, and fragrance. The molecular and genetic events that determine some of these flower characters cannot be studied using model species such as Arabidopsis thaliana, or at least only in a limited manner. In this review, we comment on the recent development of genetic, genomic, and transcriptomic tools for roses, and then focus on recent advances that have helped unravel the molecular mechanisms underlying several rose floral traits.

Fig. 1.

Schematic representation of major steps of modern rose genealogy. Based on Raymond (1999).

Fig. 2.

Models showing the control of flowering for once- and recurrent-flowering Rosa sp. and Fragaria vesca cultivars. Adapted from Iwata et al. (2012) and Koskela et al. (2012).

Fig. 3.

Double flower phenotype in Rosa. (a) Simple flower Rosa gallica. (b) Longitudinal section of a R. gallica flower. (d) Double flower of R. gallica cv Cardinal de Richelieu. (e) Longitudinal section of a double flower rose of R. gallica cv Cardinal de Richelieu. (c and f) Model showing the origin of the double flower phenotype. (c) ABC model in wild-type simple flower roses. (f) In double flower roses, a shift of the boundary between A and C functions towards the centre of the flower leads to homeotic conversion of stamens into petals. Adapted from Dubois et al. (2010).