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Maximising the value of unadapted wheat landraces for the improvement of quality traits

FC Ogbonnaya, V Matassa, J Brown, RF Eastwood, C Black, and J Panozzo

Agriculture Victoria - Horsham, Victorian Institute for Dryland Agriculture, Horsham, Victoria.


One hundred and thirty nine accessions of unadapted wheat landraces were evaluated to determine the nature and extent of genetic variation using quality characteristics. Agglomerative hierarchical clustering classified them into five distinct phenotypic groups. A group of accessions were identified that were the most diverged when compared to elite cultivars. These divergent accessions offer the most potential to improve wheat quality and can be used as donor parents in a backcrossing program to transfer potential novel variation into wheat Triticum aestivum L.

Key words

Wheat, landrace, genetic variation and quality traits.


Due to limited genetic variation for economically important traits in currently grown wheat cultivars, unadapted germplasm has become a source of genes for several biotic, abiotic stresses and quality traits. The conventional approach to the exploitation of unadapted germplasm relies on screening, identifying and using accessions that exhibit the most desirable characteristics in backcrossing to elite cultivars. These processes largely under-utilise the diversity of genes influencing complex traits such as quality.

Tanksley and McCouch (1997) proposed a paradigm shift in which the most divergent accession(s) relative to elite cultivars are used to increase genetic variability for the improvement of quantitative traits. This strategy was used successfully to improve quality traits in tomatoes (Bernacchi et al. 1998, Fulton et al. 2000) and yield in rice (Xiao et al. 1998). In this study, we explore the use of quality traits to gauge the level of genetic diversity of unadapted wheat landraces relative to known wheat cultivars and to identify the most diverse unadapted landrace accession(s).

Materials and Methods

Grain quality data were obtained from landraces that were grown in field trials in 1995 and 1996. Details of the field trials, sample preparation and analysis of quality traits were reported by Black et al. (2000). In order to detect patterns of genetic relationship in the landraces, data analysis on the means of 13 quality traits was initially performed based on the Euclidean distance matrix. Output from this was analysed using an agglomerative hierarchical clustering method with complete linkage strategy. This was followed by ANOVA to determine differences between and within clusters.

Results and Discussion

The results of Euclidean distance similarity matrix revealed that some of the accessions were duplicates (data not shown). This reduced the accessions to 75 which clustered into five distinct groups with the largest group in cluster 2 containing approximately 30% of the accessions evaluated (Fig 1). There were significant differences between the five clusters for 13 quality traits measured except for grain weight and SDS volume (data not shown). The fact that significant differences exists between the accessions within a cluster and between clusters for 11 of the quality traits evaluated suggests that genetic variation exist amongst the landraces that can also be exploited for the improvement of bread wheat. This classification should facilitate the systematic use of the accessions to improve the quality of elite bread wheat cultivars.

Cluster 1 contained four of the seven wheat cultivars used as controls and is characterised as soft biscuit type cultivars with relatively weak dough. The remaining wheat cultivars used as controls were dispersed in clusters 2, 3 and 4 and appeared consistent with their bread wheat quality classification.

Cluster 5 was the most diverged consisting of 15 unadapted landraces accessions divided into three sub-groups. It is hypothesised that since accessions in cluster 5 are the most isolated and distinct from elite cultivars, they may contain novel genetic variation that could be incorporated into bread wheat.

Figure 1. Dendogram based on hierarchical clustering of 13 quality traits of 75 wheat landraces including seven wheat cultivars.


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