Haploid Durum Wheat Production via Hybridization with Maize

Haploids are useful in basic studies on intergenomic relationships, in molecular studies, and in practical breeding. Haploid production in durum wheat has had limited success. 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 (Triticum turgidum L., 2 n= 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 maize (Zea mays L.) cultivars resulted in haploid embryos. In vitro culture of these embryos produced haploid green seedlings. Post-pollination treatment with 3 mg L -1 2,4-D and 120-180 mg L -1 AgNO 3 gave the best yield of embryos, whereas 3 mg L -1 2,4-D plus 120 mg L -1 AgNO 3 promoted the conversion of embryos into plantlets. We produced a total of 142 mature, green haploid seedlings which included haploids with and without the homoeologous pairing suppresser gene, Ph1. Clear genotypic differences in haploid production were observed, Medora with 3 mg L -1 2,4-D + 180 mg L -1 AgNO 3 being the highest yielder. Renville proved to be more consistent yielder of haploid embryos as well as seedlings, over all treatments. 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.