In intergeneric crossings between Diplotaxis tenuifolia (2n = 22, DtDt) and five cultivars of Raphanus sativus (2n = 18, RR), an intergeneric F 1 hybrid was produced from the crossing of D. tenuifolia × R. sativus cv. '4-season leaf' through ovary culture followed by embryo culture. The induced amphidiploid (2n = 40, DtDtRR) showed well-regulated meiotic features at PMCs and a high pollen fertility (75 %). Three BC 1 hybrids with DtRR (2n = 29) or DtDtR (2n = 31) genome constitutions were obtained by the same embryo rescue procedure in the crossings of amphidiploid × R. sativus and D. tenuifolia × amphidiploid, respectively. In the successive backcrossings of two BC 1 hybrids (DtRR, 2n = 29) to R. sativus, 102 BC 2 hybrids were obtained by conventional pollination. In the reciprocal crossing of R. sativus × BC 1 hybrids, 12 reciprocal BC 2 hybrids were also produced without embryo rescue. The somatic chromosome number of 89 BC 2 hybrids with D. tenuifolia cytoplasm and 12 reciprocal BC 2 hybrids with R. sativus cytoplasm ranged from 2n = 18 to 2n = 23 that were estimated to carry 2n = 18 chromosomes of R. sativus and zero to five chromosomes of D. tenuifolia. Among them, 24.7 % of the BC 2 hybrids and 41.6 % of the reciprocal BC 2 hybrids were assumed to be monosomic addition lines (MALs, 2n = 19). The novel intergeneric hybrids obtained in this study could become useful materials for investigating the genetic effects on C 3 -C 4 intermediate traits at the genomic and chromosomal levels, as well as for estimating the performance of genetic improvement in Brassicaceae.

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