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

许多育种者试图用日本杜鹃与几种常绿杜鹃花进行多次杂交，以获得黄花常绿杜鹃。1996年，我们通过日本杜鹃与常绿杜鹃花的三次杂交，成功地获得了绿色苗木。白化植株的出现频率较高是由于常绿植物的质体与日本大麦的核基因组不亲和所致，绿色植物只有在其质体来源于日本大麦时才会出现。因此，在绿苗获得频率较高的情况下，应以日本大麦为种子亲本进行杂交。但由于未能设置太空舱，这样的穿越没有成功。在本研究中，我们通过东北红豆杉与日本红豆杉的杂交获得了一株绿色幼苗。这株幼苗是三倍体，具有来自常绿植物的质体体。在以前的报道中，我们调查了白化苗的出现似乎起源于ptDNA和核DNA的不亲和性。然而，从这些发现来看，具有核基因组的三倍体幼苗似乎是来自东北红豆杉(2x)和来自日本红豆杉(X)的三倍体幼苗都是绿叶的，没有表现出不亲和性。

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.