Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/1998
Publication Date: N/A
Citation: Interpretive Summary: Haploid plants with half the chromosome number are useful in basic studies and in practical plant breeding. Although haploids have been produced in spring wheat, haploid production in durum wheat has had limited success in the past. We produced a large number of haploids in seven agronomically important durum cultivars and three cytogenetic stocks which carried a mutation or had one chromosome replaced by another. These genotypes were first crossed with maize which resulted in the formation of embryos. During the developmental stages of the embryos, the maize chromosomes were eliminated, resulting in haploid durum wheat embryos. These embryos were then cultured on artificial media to recover haploid durum plants. Various hormonal treatments helped to increase the efficiency of haploids. It appears that the substitution of chromosome 5D for 5B confers on durum higher ability to produce haploids.
Technical Abstract: Haploids are useful in basic studies on intergenomic relationships, in molecular studies, and in practical breeding. The objective of this study was to develop an efficient method of durum haploid production via maize pollination. Pollination of seven agronomically superior durum wheat (2n=4x=28; AABB) cultivars [Durox, Langdon(LDN), Lloyd, Medora, Monroe, Renville and Vic] and three important cytogenetic stocks [LDN 5D(5B), LDN Ph1 ph1b and Cappelli ph1c ph1c] with pollen from three commercial maize cultivars resulted in haploid embryos. In vitro culture of these embryos produced haploid green seedlings. A number of post-pollination treatments were applied to enhance the recovery of haploids. Sixteen to 18 days after pollination, haploid embryos were rescued on hormone-free MS medium. An endosperm nursing technique was used to generate haploid seedlings from small embryos of some genotypes that failed to grow on MS medium. A combined treatment with 3 mg/L 2,4-D and 120-180 mg/L AgNO3 improved the yield of haploid embryos (1.1% to 30.8%) and haploid mature green seedlings (0 to 13.5%). Whereas 3 mg/L 2,4-D combined with 180/L AgNO3 gave the best yield of embryos, 3 mg/L 2,4-D plus 120 mg/L AgNO3 promoted the conversion of embryos into plantlets. Thus, we have produced a total of 142 mature, green haploid seedlings. Clear genotypic differences in haploid production were observed, Medora being the highest yielder, Renville the second, and Cappelli the lowest. Among the three Langdon genotypes - Langdon Ph1 ph1b, Langdon 5D(5B) substitution line, and normal Langdon - the substitution line gave the best response. It appears, therefore, that the substitution of chromosome 5D for 5B confers on durum higher ability to produce haploids.