MECHANISM OF THE APPEARANCE OF ALBINO SEEDLINGS IN REMOTE CROSSINGS IN AZALEAS

Many breeders attempted that many crossing between Rhododendron Japonicum and several evergreen azaleas for the obtainment of yellow-flowered evergreen azaleas. But almost all seedlings were albino and have never grown at anthesis. In 1996, we succeeded to obtain the green seedlings by three way crossings among R.japonicum and evergreen azaleas. We reported that high frequency of albino plant appearance was caused by incompatibility between plastome from evergreen species and nuclear genome from R.japonicum, and that green plants appeared only when their plastomes were originated from R.japonicum. Therefore, to succeed the frequency of green plant obtainment, R.japonicum should be used as seed parents in such crosses. But such crossings are unsuccessful because of failure to set capsules. IN this study, we obtained a green seedling from the single crossing between R. kiusianum x R. japonicum. This seedling was triploid and have plastome from evergreen species. In the previous reports, we investigated that the appearance of albino seedlings seem to originated in the incompatibility between ptDNA and nuclear DNA. From these findings, however, it seems that the triploid seedlings that have nuclear genome originated from R. kiusianum (2x) and originated from R. japonicum (x) show green leaves and not show the incompatibility.