Molecular mapping of genomic regions associated with wheat seedling growth under osmotic stress

Abstract

A quantitative trait loci (QTL) approach was applied to dissect the genetic control of the common wheat seedling response to osmotic stress. A set of 114 recombinant inbred lines was subjected to osmotic stress from the onset of germination to the 8 th day of seedling development, induced by the presence of 12 % polyethylene glycol. Root, coleoptile and shoot length, and root/shoot length ratio were compared under stress and control conditions. In all, 35 QTL mapping to ten chromosomes, were identified. Sixteen QTL were detected in controls, 17 under stressed conditions, and two tolerance index QTL were determined. The majority of the QTL were not stress-specific. In regions on five chromosome arms (1AS, 1BL, 2DS, 5BL and 6BL) the QTL identified under stress co-mapped with QTL affecting the same trait in controls, and these were classified as seedling vigour QTL, in addition to those expressed in controls. Tolerance-related QTL were detected on four chromosome arms. A broad region on chromosome 1AL, including five QTL, with a major impact of the gene Glu-A1 (LOD 3.93) and marker locus Xksuh9d (LOD 2.91), positively affected root length under stress and tolerance index for root length, respectively. A major QTL (LOD 3.60), associated with marker locus Xcdo456a (distal part of chromosome arm 2BS) determined a tolerance index for shoot length. Three minor QTL (LOD < 3.0) for root length and root/shoot length ratio under osmotic stress were identified in the distal parts of chromosome arms 6DL (marker locus Xksud27a) and 7DL (marker locus Xksue3b). Selecting for the favourable alleles at marker loci associated with the detected QTL for growth traits may represent an efficient approach to enhance the plants' ability to maintain the growth of roots, coleoptile and shoots in drought-prone soils at the critical early developmental stages.

QTL mapping for germination of seeds obtained from previous wheat generation under drought

“…The use of molecular markers in genotypes selection is now widely applied in breeding programs [36,37] but requires prior determination of the main loci of genes associated with the desired traits [38][39][40], which is made possible by QTL analysis. The experiments conducted on wheat grain germinating under osmotic stress or control conditions resulted in mapping different QTLs distributed throughout the genome [10], suggesting a possible role of stress factors in the change of grain vigour. Wild species related to bread wheat show remarkable genetic diversity essential to the improvement of the quality of cultivated plants.…”

“…Therefore, measurable results can be expected from quantitative trait loci (QTL) analysis, based on phenotypic data [9]. The inheritance of traits associated with the process of germination and growth of a seedling has been studied in wheat [10], Brassica ssp. [7], rice [11], barley [12], and sunflower [13].…”

Genomic Regions for Embryo Size and Early Vigour in Multiple Wheat (Triticum aestivum L.) Populations

“…Allelic effects and chromosomal location are given in Tables 7-9. It is important to note that although several publications have reported QTL for traits related to early vigour (e.g., [29][30][31][32][33]), to date there have been no QTL reported for embryo size in wheat. The QTL shown in green indicate the first parent (e.g., Sunco or Cranbrook) contributes a positive allele (e.g., increased embryo width) while a red QTL indicates the first parent contributes a negative allele (e.g., reduced embryo width) at the designated QTL.…”

“…Further, it has been previously reported [28] that the correlation of seed size to early vigour performance might be more pronounced under conditions of moisture stress than in well-watered conditions. Genomic regions and underlying genetic loci associated with early vigour have been reported for wheat by several sources [29][30][31][32][33]. However, to date there have been no published reports describing genes or Quantitative Trait Locus (QTL) for embryo size in wheat.…”

Recent advances in molecular tool development for drought tolerance breeding in cereal crops: a review

“…However, QTL mapping related to drought stress can be applied to any growth stage from germination to grain filling stage. QTLs corresponding to different morphological and physiological traits in various mapping populations have been identified like growth of shoot and roots (Landjeva et al, 2008); osmotic adjustment (Morgan, Tan, 1996), grain yield (Kirigwi et al, 2007;Salem et al, 2007) and thousand grain weight (Nezhad et al, 2012).…”