We attempted to produce intersectional hybrids between
Vaccinium uliginosum L. (2 n = 6 x = 72) of the section
Vaccinium, a wild species native to Japan, and 8 rabbiteye blueberry (
V. virgatum Aiton) cultivars (2 n = 6 x = 72) of the section
Cyanococcus using reciprocal crossing. Fertile seeds were obtained from 5 of 8 cross combinations, of which
V. uliginosum was used as a seed parent, whereas no fertile seed was obtained when
V. uliginosum was used as a pollen parent. This result showed that unilateral cross incompatibility would exist in the crosses between
V. uliginosum and
V. virgatum. Consequently, 13 seedlings were obtained from the crosses and 12 seedlings were from the cross between
V. uliginosum and T100. These 12 seedlings (KT strain) were used for evaluating their hybridity, ploidy level, nuclear DNA content, morphological characteristics, and fruit quality. RAPD analysis showed that 10 of the 12 seedlings of the KT strain were intersectional hybrids between
Vaccinium and
Cyanococcus. The hybrids were also confirmed to be hexaploids by flow cytometory; however, the nuclear DNA contents among their hybrids were different. Some of them grew vigorously on their own root in south-west Japan, and 8 hybrids bore flowers. While 2 of the 8 hybrids did not produce fertile pollen, all 8 hybrids set fruits in an open field without artificial pollination. Each fruit had a peduncle with a pair of bractlet leaves on its middle part which often attached to the peduncle of
V. uliginosum. The fruit quality was different among their hybrids, sugar and organic acid contents in fruit of KT-9 and 15 were almost equal to those of T100, and anthocyanin and polyphenol contents and antioxidant activity in fruit of KT-4, 9 and 15 were almost equal or above those of
V. uliginosum. In the future, these hybrids may be useful as breeding material to establish some new cultivars with high quality and functionality adaptable to south-western Japan.
View full abstract