Molecular Mapping and Genomics of Grain Yield in Durum Wheat: A Review

Abstract

Durum wheat is the most relevant cereal for the whole of Mediterranean agriculture, due to its intrinsic adaptation to dryland and semi-arid environments and to its strong historical cultivation tradition. It is not only relevant for the primary production sector, but also for the food industry chains associated with it. In Mediterranean environments, wheat is mostly grown under rainfed conditions and the crop is frequently exposed to environmental stresses, with high temperatures and water scarcity especially during the grain filling period. For these reasons, and due to recurrent disease epidemics, Mediterranean wheat productivity often remains under potential levels. Many studies, using both linkage analysis (LA) and a genome-wide association study (GWAS), have identified the genomic regions controlling the grain yield and the associated markers that can be used for marker-assisted selection (MAS) programs. Here, we have summarized all the current studies identifying quantitative trait loci (QTLs) and/or candidate genes involved in the main traits linked to grain yield: kernel weight, number of kernels per spike and number of spikes per unit area.

Keywords: QTLs; Triticum turgidum ssp. durum; molecular markers; yield components.

Figure 1

Histograms showing the number of quantitative trait loci (QTLs) detected on each chromosome of durum wheat for each yield-related trait selected and described in this study. Kernel length (KL, 33 QTLs), kernel width (KW, 30 QTLs) and thousand-kernel weight (TKW, 201 QTLs) associated with the kernel weight (in green); kernels number per spike (KNS, 66 QTLs), kernels number per spikelet (KNSL, 24 QTLs) and spikelets number per spike (SLNS, 80 QTLs) associated with kernels number (in blue); grain yield (GY, 142 QTLs), kernels number per square meter (KNM, 43 QTLs) and spike number per square meter (SNM, 23 QTLs) associated with kernels number per unit area (in purple).

Figure 2

All markers associated with QTLs for grain yield-related traits reported in durum wheat genetic studies, whose marker are present in the consensus map developed by Maccaferri et al. [27]. On the left of the chromosome, the marker position in cM, which corresponds to that of the consensus map, is presented. On the right of the chromosome, the name of the markers and QTLs with a moderate/major effect on kernel weight (in green) and kernels number (in blue) traits is presented. Moreover, major QTLs with a pleiotropic effect on different categories are shown in red. QTLs detected in different populations are shown in bold.