Studies On Rose Breeding For Resistance To Powdery Mildew With Rosa Laxa And Modern Rose

The rose is one of the most prominent ornamental plants in the world. They are famous for abundant cultivars and excellent ornamental attributes, but some resistance genes had lost because of the long-term directional selection and artificial cultivation. Powdery mildew cause by Podosphaera pannosa var. rosae is the most serious and widespread fungal disease that adversely affects the yield and quality of rose. So new rose germplasm resources should be introduced into modern rose. Rosa laxa has excellent resistance to powdery mildew by assessment. It is one of important ways to breed new rose with srong resistance to powdery mildew to introduce R. laxa’ prominent genes into rose.In this study, R. laxa and modern rose and traditional rose were used as parents to breed rose cultivars with stong resistance to powdery mildew. The hybrid authenticity identification of offspring was confiemed and the capability to resistance to powdery mildew was assessed. The main results were as follows:1. R laxa and modern rose and traditional rose were used as parents,106cross combinations were designed in2011and2012,4904flowers were pollinated,7457seeds and39seedlings were obtained, and44groups of cross combination were chosen which had higher rate of fruit setting more than25%.2. In this study, F1hybrids were identified using the SSR molecular marker process and morphology identification, the ploidy was analysised by flow cytometry, the karyotypes of parents and their interspecific hybrids were analyzed to investigate the genetic characteristics by traditional squashing. The results showed that modern roses are tetraploid, R. laxa is diploid, and F1hybrids were triploid, except that one of the hybrids between R. laxa and ’Kardinal’ was diploid. The karyotype formula of R.laxa was12m+2sm belonging to1A. The karyotype formula of ’Kardinal’,’Solidor’,’Wizen’were28m,28m,24m(2SAT)+4sm, respectively, of which belonged to1A,1B and2B. Among the hybrids, the karyotype formula included1A, IB2A and2B. Identification by SSR and phenotypic observations suggest that, in addition to A5the other offspring are hybrids.3.The resistance to the powery mildew of parents and15offsprings get from cross combinations of R laxa (female)×’Kardina’(male), R. laxa (female)×’Solidor’(male) and R.laxa (female)×’Yuzen’. It is indicated that5materials had relative high powdery resistance,8materials had middle resistance. The results provide a basis for further comprehensive evaluation.In this study, on the basis of hybridization, identification and evaluation, some F1hybrids get from combination of R. laxa and modern roses and traditional roses. These roses could be good materials for new cultivars or intermediate materials.