Inheritance of Perpetual Blooming in Rosa chinensis ‘Old Blush’

Perpetual blooming is one of the most important biological and economical traits in modern rose, while the genetic basis underlining the control of this trait is poorly investigated. With an aim in dissecting the genetic determinism of perpetual blooming, we developed six rose populations (OB, W, F1, F2, BC1OB and BC1W) derived from a WOB population [interspecific diploid hybridization between Rosa chinensis ‘Old Blush’ (OB) and R. wichuriana ‘Basye’s Thornless’ (W)]. Perpetual blooming is absent both in a F1 population with 296 individuals and a BC1W population (W as the backcross parent) with 150 individuals. However, the perpetual blooming trait showed a typical 3:1 segregation in a backcross population BC1OB with OB as the backcross parent. In this population with 300 individuals, 83 plants had the perpetual blooming phenotype while the other 217 featured non-perpetual blooming, indicating that the perpetual blooming trait is very likely controlled by two recessive genes in R. chinensis (rpb1 and rpb2). These genetic data suggest that the inheritance of rose perpetual blooming may be controlled by a complex mechanism.