J. Flink

Complex interspecific hybridization in barley (Hordeum vulgare L.) and the possible occurrence of apomixis

SummarySeveral complex hybrids were produced from the combination [(Hordeum lechleri, 6x xH. procerum, 6 x) × H. vulgare, 2 x]. Crosses with six diploid barley lines resulted in triple hybrids, most of which had a full complement of barley chromosomes (no. 1–7), but were mixoploid with respect to alien chromosomes (19–22). In one combination, chromosome no. 7 was duplicated. Meiosis in triple hybrids showed low, but variable pairing (1.3–5.5 chiasmata per cell). The syndesis probably did not include the barley chromosomes. Direct back-crosses to di- and tetraploid barley lines were unsuccessful. Chromosome doubling of the triple hybrid based on cv ‘Pallas’ resulted in a plant with 2n = 53–56, which had an increased fertility. Backcrosses to one di- and one tetraploid barley line resulted in offspring. The cross made with the tetraploid line (‘Haisa II’), produced a 28-chromosomic plant in which the male parental genome was absent. We suspect that this plant may have arisen through parthenogenetic development of a reduced female gamete. The other cross with a diploid line (‘9208/9’) resulted in plant with 2n = 51–53. The most likely explanation for this second plant is that an unreduced gamete from the amphiploid was fertilized by a normal gamete from the backcross parent, and during early embryo development, some chromosomes were eliminated.

Triple hybridization with cultivated barley (Hordeum vulgare L.)

SummaryA crossing programme for trispecific hybridization including cultivated barley (Hordeum vulgare L.) as the third parent was carried out. The primary hybrids comprised 11 interspecific combinations, each of which had either H. jubatum or H. lechleri as one of the parents. The second parent represented species closely or distantly related to H. jubatum and H. lechleri. In trispecific crosses with diploid barley, the seed set was 5.7%. Crosses with tetraploid barley were highly unsuccessful (0.2% seed set). Three lines of diploid barley were used in the crosses, i.e. ‘Gull’, ‘Golden Promise’ and ‘Vada’. Generally, cv ‘Gull’ had high crossability in crosses with related species in the primary hybrid. It is suggested that ‘Gull’ has a genetic factor for crossability not present in cv ‘Vada’ and cv ‘Golden Promise’. One accession of H. brachyantherum used in the primary hybrid had a very high crossability (seed set 54.7%) in combination with cv ‘Vada’ but no viable offspring was produced. In all, two trispecific hybrids were raised, viz. (H. lechleri x H. brevisubulatum) x ‘Gull’ (2n=7–30) and (H. jubatum x H. lechleri) x ‘Gull’ (2n=20–22). The first combination invariably had a full complement of seven barley chromosomes plus an additional chromosome no. 7, but a varying number of chromosomes (19–22) of the wild-species hybrid. The second combination had a full set of barley chromosomes. The meiotic pairing was low in both combinations.