Abstract
Genomic regions responsible for accumulation of grain iron concentration (Fe), grain zinc concentration (Zn), grain protein content (PC) and thousand kernel weight (TKW) were investigated in 286 recombinant inbred lines (RILs) derived from a cross between an old Indian wheat variety WH542 and a synthetic derivative (Triticum dicoccon PI94624/Aegilops squarrosa [409]//BCN). RILs were grown in six environments and evaluated for Fe, Zn, PC, and TKW. The population showed the continuous distribution for all the four traits, that for pooled Fe and PC was near normal, whereas, for pooled Zn, RILs exhibited positively skewed distribution. A genetic map spanning 2155.3cM was constructed using microsatellite markers covering the 21 chromosomes and used for QTL analysis. 16 quantitative trait loci (QTL) were identified in this study. Four QTLs (QGFe.iari-2A, QGFe.iari-5A, QGFe.iari-7A and QGFe.iari-7B) for Fe, five QTLs (QGZn.iari-2A, QGZn.iari-4A, QGZn.iari-5A, QGZn.iari-7A and QGZn.iari-7B) for Zn, two QTLs (QGpc.iari-2A and QGpc.iari-3A) for PC, and five QTLs (QTkw.iari-1A, QTkw.iari-2A, QTkw.iari-2B, QTkw.iari-5B and QTkw.iari-7A) for TKW were identified. The QTLs together explained 20.0%, 32.0%, 24.1% and 32.3% phenotypic variation, respectively, for Fe, Zn, PC and TKW. QGpc.iari-2A was consistently expressed in all the six environments, whereas, QGFe.iari-7B and QGZn.iari-2A were identified in two environments each apart from pooled mean. QTkw.iari-2A and QTkw.iari-7A, respectively, were identified in four and three environments apart from pooled mean. A common region in the interval of Xgwm359-Xwmc407 on chromosome 2A was associated with Fe, Zn, and PC. One more QTL for TKW was identified on chromosome 2A but in a different chromosomal region (Xgwm382-Xgwm359). Two more regions on 5A (Xgwm126-Xgwm595) and 7A (Xbarc49-Xwmc525) were found to be associated with both Fe and Zn. A QTL for TKW was identified (Xwmc525-Xbarc222) in a different chromosomal region on the same chromosome (7A). This reflects at least a partly common genetic basis for the four traits. It is concluded that fine mapping of the regions of the three chromosomes of A genome involved in determining the accumulation of Fe, Zn, PC, and TKW in this mapping population may be rewarding.
Highlights
Both plants and human beings require an optimum daily intake of protein, vitamins, and micronutrients for their normal physiological and biochemical activity
Individual mean values of recombinant inbred lines (RILs) for Fe, zinc concentration (Zn), protein content (PC), and thousand kernel weight (TKW) tested in six environments are given in supplementary tables as S1 Table, S2 Table, S3 Table and S4 Table, respectively
The population showed the continuous distribution for Fe, Zn, PC and TKW (Figs 1–3), that for pooled Fe and PC was near normal, whereas, for pooled Zn, RILs exhibited positively skewed distribution
Summary
Both plants and human beings require an optimum daily intake of protein, vitamins, and micronutrients for their normal physiological and biochemical activity. One-fourth of the population across the globe suffers from anemia caused by Fe deficiency [3], which resulted in the loss of around 46,000 disability adjusted life years in 2010 [4]. Insufficient Fe intake affects physical growth and cognitive ability [5], so the reproductive ability and work efficiency [6]. Insufficient intake of Zn causes excessive weight loss, depression, psychosis, diarrhea, impaired growth and development, altered reproductive biology, gastro-intestinal problems and impaired immunity [8]. Protein and micronutrient malnutrition continue to be a major health burden in developing countries, where pregnant women and young children are vulnerable [9]. High TKW can improve the flour yield and affect the milling quality of wheat grains [10]
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