Synthetic Brassica rapa-Raphanus sativus amphidiploid lines developed by reciprocal hybridization.

Two amphidiploid lines, Brassicoraphanus (AR-89, 2n = 38) and Raphanobrassica (RA-89, 2n = 38), derived from reciprocal hybridization between Brassica rapa (AA, 2n = 20) and Raphanus sativus (RR, 2n = 18) were developed through the generation of F, hybrids and subsequent chromosome doubling. Chromosomal stability and amphidiploidy were confirmed for F 7 plants of two lines, in both mitosis and meiosis, where 2n = 38 chromosomes in root-tip cells and chromosomal configurations of 15-19 bivalents and 0-8 univalents in pollen mother cells were observed, respectively. Hybridity was also ascertained by random amplified polymorphic DNA analysis using selected primers. Two lines resembled each other for morphological characters such as plant type, inflorescence and roots, but differed in the veining of petals and in pod shape. Selected plants of these two lines produced viable seeds to some extent following both self- and cross-pollination. Two lines could also be maintained through open-pollination among the selected plants (2n = 38) with higher pollen fertility.