Reduced-stature Rosa species through in vitro mutagenesis

Baig, M. M. Q., Hafiz, I. A., Abbasi, N. A., Yaseen, M., Akram, Z. and Donnelly, D. J. 2012. Reduced-statureRosaspecies through in vitro mutagenesis. Can. J. Plant Sci. 92: 1049-1055. Plant height is one of the main attributes affecting general appeal and beauty of roses (Rosa spp.). Among the highly scented rose species, R. gruss an teplitz, R. centifolia, and R. borboniana, have great potential horticultural and commercial value. However, their large plant size detracts from recent trends towards selection of smaller plants for emerging markets and high-density plantations. This study aimed to produce reduced-stature plants through in vitro mutagenesis using gamma irradiation (Co60). Shoot tips cut from micropropagated shoots were exposed up to 120 Gy. Irradiated shoot tips were micropropagated for one culture cycle. Surviving shoots were rooted in vitro then acclimatized for 2 mo in a greenhouse. The shoot tip LD50 after gamma irradiation was species-dependent and 33-54 Gy. In this dose range, survival during in vitro rooting and acclimatization was also affected; this was 64 to 24% and 34 to 14% of control values, respectively. Acclimatized transplants were 17 to 56% smaller with 16 to 51% less leaf area compared with the controls. In order to ascertain stability putative reduced-stature roses will be monitored for vegetative and floral characteristics over the next few years. This study adds to the ongoing efforts to obtain reduced-stature rose plants for horticultural purposes.