Cross-compatibility and the polyploidy of progenies in reciprocal backcrosses between diploid carnation (Dianthus caryophyllus L.) and its amphidiploid with Dianthus japonicus Thunb

Reciprocal backcrosses were carried out between six lines of carnation (Dianthus caryophyllus L.) and one line of amphidiploid from D. caryophyllus x Dianthus japonicus Thunb. When carnation was used as the maternal parent, 24 progeny were obtained from three lines of carnation. Flow cytometric analysis revealed that they consisted of 4 tetraploid hybrid plants, 3 triploid hybrid plants and 17 diploid maternal-type progeny. The tetraploid hybrid plants were obtained from only one line of carnation used as maternal parent. When the amphidiploid was used as maternal parent, 137 progeny were obtained by pollination with 5 lines of carnation. All of them were confirmed to be triploid hybrids by flow cytometric analysis, PCR-RFLP analysis also revealed that each hybrid had DNA fragments originated from carnation and D. japonicus. The ploidy level of these hybrids was confirmed by counting chromosome numbers in root-tip cells. Flow cytometric analysis also revealed that the tetraploid hybrids had three genomes of carnation and one genome of D. japonicus, suggesting that the carnation line '02spROBA! produced unreduced female gametes. Since not only the tetraploid hybrids but also the triploid ones were fertile and have some of the profitable characters of D. japonicus such as broad leaf, strong stem and heat tolerance, they are expected to use for future breeding in carnation. (C) 2007 Elsevier B.V. All rights reserved.