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 d urum wheat has had limited success. The objective of this study was to develop an efficient method of durum haploid production via maize pol lination. Pollination of seven agronomically superior durum wheat (Tri ticum turgidum L., 2n = 4x = 28, AABB) cultivars [Durox, Langdon (LDN) , Lloyd, Medora, Monroe, Renville, and Vic] and three important cytoge netic stocks [LDN 5D (5B), LDN Phl ph1b, and Cappelli ph1c ph1c with p ollen from three maize (Zea mays L.) cultivars resulted in haploid emb ryos. In vitro culture of these embryos produced haploid green seedlin gs. Post-pollination treatment with 3 mg L-1 2,4-D and 129-180 mg L-1 AgNO3 gave the best yield of embryos, whereas 3 mg L-1 2,4-D plus 120 mg L-1 AgNO3 promoted the conversion of embryos into plantlets. We pro duced a total of 142 mature, green haploid seedlings which included ha ploids with and without the homoeologous pairing suppresser gene, Ph1. Clear genotypic differences in haploid production were observed,,Medo ra with 3 mg L-1 2,4-D + 180 mg L-1 AgNO3 being the highest yielder. R enville proved to be more consistent yielder of haploid embryos as wel l as seedlings, over all treatments. Among the three Langdon genotypes - Langdon Ph1 ph1b, Langdon 5D(5B) substitution line, and normal Lang don - the substitution line gave the best response. It appears, theref ore, that the substitution of chromosome 5D for 5B confers on durum hi gher ability to produce haploids.