Abstract
A near-isogenic line (NIL-7A-B-2), introgressed with a quantitative trait locus (QTL) on chromosome 7AS from wild emmer wheat (Triticum turgidum ssp. dicoccoides) into the background of bread wheat (T. aestivum L.) cv. BarNir, was recently developed and studied in our lab. NIL-7A-B-2 exhibited better productivity and photosynthetic capacity than its recurrent parent across a range of environments. Here we tested the hypothesis that root-system modifications play a major role in NIL-7A-B-2’s agronomical superiority. Root-system architecture (dry matter and projected surface area) and shoot parameters of NIL-7A-B-2 and ‘BarNir’ were evaluated at 40, 62, and 82 days after planting (DAP) in a sand-tube experiment, and root tip number was assessed in a ‘cigar-roll’ seedling experiment, both under well-watered and water-limited (WL) treatments. At 82 DAP, under WL treatment, NIL-7A-B-2 presented greater investment in deep roots (depth 40–100 cm) than ‘BarNir,’ with the most pronounced effect recorded in the 60–80 cm soil depth (60 and 40% increase for root dry matter and surface area, respectively). NIL-7A-B-2 had significantly higher root-tip numbers (∼48%) per plant than ‘BarNir’ under both treatments. These results suggest that the introgression of 7AS QTL from wild emmer wheat induced a deeper root system under progressive water stress, which may enhance abiotic stress resistance and productivity of domesticated wheat.
Highlights
Drought, the major stress factor limiting crop productivity worldwide (Boyer, 1982; Araus et al, 2008), is expected to increase due to global climate change (Wheeler and von Braun, 2013)
In agreement with the difficulties involved in root-system characterization, studies of genetic variability and quantitative trait locus (QTL) mapping of root traits are limited in number and usually conducted at the seedling stage (Atkinson et al, 2015, and references therein), they are of minor relevance for mature field-grown plants
SNP genotyping of the resultant near-isogenic lines (NILs) provided a high resolution confirmation for the introgressed genomic regions and showed that between 3.3 and 9.5% of the markers were introgressed from the donor parent including the targeted genomic regions (Merchuk-Ovnat et al, 2016a), or 3.6% for NIL-7A-B-2 examined in the current study
Summary
The major stress factor limiting crop productivity worldwide (Boyer, 1982; Araus et al, 2008), is expected to increase due to global climate change (Wheeler and von Braun, 2013). This poses a major challenge for the improvement of crop productivity to meet the demands of a growing human population. Breeding high-yield drought-resistant cultivars of major crops, such as wheat (Triticum spp.), is considered a sustainable approach to meeting this challenge.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
