Breeding for Manganese Efficiency in Durum Wheat

Abstract

Manganese deficiency is a major constraint to the growth of cereals on alkaline soils particularly for durum and bread wheat which are generally more intolerant than barley. Genetic variation for manganese efficiency exists in current germplasm of bread wheat and has recently been identified in durum wheat. Development of a screening technique and a selection criterion has enabled further genetic studies, resulting in a hypothesis that manganese efficiency is controlled by at least two major genes. This has made breeding for manganese efficiency feasible. The development of the molecular markers for loci conferring Mn efficiency could accelerate the breeding of manganese efficient varieties. To identify markers linked to a locus conferring Mn efficiency, Amplified Fragment Length Polymorphism (AFLP) was combined with Bulked Segregant Analysis (BSA). A total of 176 primer combinations were used to compare the bulk samples the two parents within an inbred population (189 F2's) derived from a Mn-efficient (Stojocri 2) x Mn-inefficient (Hazar) durum wheat. Twenty pairs of primers revealed at least one polymorphic band between the two contrasting bulks. The segregation of each of these bands was evaluated in 80 F2's selected from the two extreme ends of the bioassay distribution (40 individuals from each of the Mn-efficient and Mn-inefficient ends). Two AFLP markers showed significant linkage to the Mn efficiency and explained up to 40% and 45% of the genetic variation respectively. Linkage studies showed that these markers were not significantly linked. Cloning, sequencing and conversion of a selected AFLP marker to a PCR based assay is in progress. Studies of the traits in the simpler (durum) genome are well under way and is described below. In hexaploid wheat screening for potential donors of manganese efficiency to current Australian varieties has been accomplished, Doubled haploid populations have been produced and screened for manganese efficiency, and identification of linked makers has commenced.