BREEDING OF ROSA RUGOSA THUNB. USING DIFFERENT TISSUE CULTURE METHODS

Abstract

Rosa rugosa Thunb. as female plants in breeding of roses are the best for parks and gardens in the Northern maritime climate: they have high resistance to fungal diseases, have compact 1.2-2.5 m high bushes, abundant and repeated flowering, need no covering in winter. The flowers are large and fragrant; the colour ranges from clear white to different shadings of rosy. The aim of our main study is to obtain hybrids with different habitus (climber) and dissimilar colours for R. rugosa -yellow, orange and bright red. To expand the variability and to obtain positive results in incompatible crosses with male plants from floribunda and climber roses with different colours, in vitro culture methods are used: (1) the treatment of callus cultures with high doses of phytohormones with initiation of somatic embryogenesis, (2) direct development of natural embryos in vitro, (3) the initiation of somatic embryogenesis from immature embryos. The information from other laboratories offered the cultivation of immature tea hybrid and floribunda rose embryos isolated 25 or more days after crossing. The prolongation of development of embryos in hips is one of the most important factors for getting the regenerants in vitro. 100% downfall of embryos, isolated from hips after one week of crossing was observed in our foregoing study. Our present experiments showed a positive experience in ensuring a successful growth and development of immature embryos in vitro isolated in an early stage of development, i.e., seven days after crossing. We had found that: (1) By repeated treatment of callus cultures with 5 - 25 mg L -1 1-naphthalene acetic acid (NAA) or indole-3-butyric acid (IBA) or 6-benzylaminopurine (BAP) no changes of further qualitative indications of regenerants ex vitro were observed. (2) The direct development of natural embryos in vitro was observed in one crossing (0.75% of isolated embryos were developed). (3) The most successful method of obtaining the regenerants was the initiation of somatic embryogenesis from immature embryos: out of six different crossings two ones resulted with germination of alive embryos (10-18% of isolated embryos were developed).