Detection of nitrogen deficiency QTL in juvenile wild barley introgression linesgrowing in a hydroponic system

Abstract

BackgroundIn this report we studied the genetic regulation of juvenile development of wild barley introgression lines (S42ILs) under two contrasting hydroponic nitrogen (N) supplies. Ten shoot and root related traits were examined among 42 S42ILs and the recurrent parent ‘Scarlett’. The traits included tiller number, leaf number, plant height, leaf and root length, leaf to root length ratio, shoots and root dry weight, shoot to root weight ratio, and chlorophyll content. Our aims were (1) to test the suitability of a hydroponic system for early detection of favourable S42ILs, (2) to locate quantitative trait loci (QTL) that control the examined traits, (3) to identify favourable wild barley alleles that improve trait performances in regard to N treatment and, finally, (4) to validate the identified QTL through comparison with previously reported QTL originating from the same parental cross.ResultsThe phenotypic data were analysed in a mixed model association study to detect QTL. The post-hoc Dunnett test identified 28 S42ILs that revealed significant (P < 0.01) effects for at least one trait. Forty-three, 41 and 42 S42ILs revealed effects across both N treatments, under low N and under high N treatment, respectively. Due to overlapping or flanking wild barley introgressions of the S42ILs, these associations were summarised to 58 QTL. In total, 12 QTL of the hydroponic N study corresponded to QTL that were also detected in field trials with adult plants of a similar S42IL set or of the original S42 population. For instance, S42IL-135, -136 and -137, revealed increasing Hsp effects for tiller number, leaf number, leaf length, plant height and leaf to root ratio on the long arm of chromosome 7H. These QTL correspond to QTL for ears per plant and plant height that were previously detected in field trials conducted with the same S42ILs or with the S42 population.ConclusionOur results suggest that the QTL we identified under hydroponic N cultivation partly correspond to QTL detected in field experiments. Due to this finding, screening of plants in early developmental stages grown in a hydroponic system may be a fast and cost effective method for early QTL detection and marker-assisted allelic selection, potentially speeding up elite barley breeding programs.

Genetic regulation of growth and nutrient content under phosphorus deficiency in the wild barley introgression library S42IL

“…Also, QTL effects on plant height in eleven S42ILs corresponded to previously reported effects of the same ILs in studies on nitrogen stress and drought stress, conducted by Hoffmann et al. () and Arifuzzaman et al. ().…”

“…The main goal of this study was to identify S42ILs which show a significant decrease or increase in growth relative to ‘Scarlett’ and to locate genes, causing these effects, on subchromosomal Hsp introgressions of the respective S42IL line. For this purpose, four hydroponic experiments under two different P levels (adequate and low) were conducted with a total of 47 selected ILs from the S42IL population and the control cultivar ‘Scarlett’, following a protocol already applied in a hydroponic nitrogen study with the same S42IL library (Hoffmann et al., ).…”

“…Subsequently, the tray was placed on top of a box filled with a nutrient solution as reported in Hoffmann et al. (). To avoid border effects due to varying light and space conditions, ‘Scarlett’ seedlings were planted in the 44 outer holes of each tray.…”

“…The composition of the standard nutrient solution was taken from Hoffmann et al. (). Phosphate concentration varied between 100 μ m (P100) and 10 μ m (P10) to study effects of P deficiency in seedlings (see Table ).…”

Performance of Ethiopian bread wheat (Tritium aestivum L.) genotypes under contrasting water regimes: potential sources of variability for drought resistance breeding

“…Seedling or early vigour, and deep root system are believed to contribute for better drought resistance (Al-Karaki, 1998;Atkinson et al, 2015;Chloupek et al, 2010;Comas et al, 2013;Lilley and Kirkegaard, 2011). Some genes that contribute to seedling drought resistance may also contribute to later stage resistance (Comas et al, 2013;Hoffmann et al, 2012). Sarker et al (2005) have reported in lentil that long root and shoot lengths at seedling stage were highly correlated with high grain yield.…”