Variation in grain Zn concentration, and the grain ionome, in field-grown Indian wheat

Abstract

Wheat is an important dietary source of zinc (Zn) and other mineral elements in many countries. Dietary Zn deficiency is widespread, especially in developing countries, and breeding (genetic biofortification) through the HarvestPlus programme has recently started to deliver new wheat varieties to help alleviate this problem in South Asia. To better understand the potential of wheat to alleviate dietary Zn deficiency, this study aimed to characterise the baseline effects of genotype (G), site (E), and genotype by site interactions (GxE) on grain Zn concentration under a wide range of soil conditions in India. Field experiments were conducted on a diverse panel of 36 Indian-adapted wheat genotypes, grown on a range of soil types (pH range 4.5–9.5), in 2013–14 (five sites) and 2014–15 (six sites). Grain samples were analysed using inductively coupled plasma-mass spectrometry (ICP-MS). The mean grain Zn concentration of the genotypes ranged from 24.9–34.8 mg kg-1, averaged across site and year. Genotype and site effects were associated with 10% and 6% of the overall variation in grain Zn concentration, respectively. Whilst G x E interaction effects were evident across the panel, some genotypes had consistent rankings between sites and years. Grain Zn concentration correlated positively with grain concentrations of iron (Fe), sulphur (S), and eight other elements, but did not correlate negatively with grain yield, i.e. no yield dilution was observed. Despite a relatively small contribution of genotype to the overall variation in grain Zn concentration, due to experiments being conducted across many contrasting sites and two years, our data are consistent with reports that biofortifying wheat through breeding is likely to be effective at scale given that some genotypes performed consistently across diverse soil types. Notably, all soils in this study were probably Zn deficient and interactions between wheat genotypes and soil Zn availability/management (e.g. the use of Zn-containing fertilisers) need to be better-understood to improve Zn supply in food systems.

Unveiling the transcriptome complexity of the High- and Low- Zinc & Iron accumulating Indian wheat (Triticum aestivum L.) cultivars

“…The development the micronutrients rich cereal grains genotypes is one of the major constituents to overcome with this problem. Various efforts have been made to increase the concentration Zn & Fe in wheat through bioforctization [Cakmak, 2008; Velu et al 2014; Velu et al 2017; Khokhar et al, 2018; Cakmak, & Kutman, 2018] also studied the effects of drought & elevated temperature in grin Zn & Fe concentration [Velu et al 2016]. Initially, QTLs map technique was widely used to obtained micronutrient rich genotypes [Velu et al 2017].…”

Novel sources of variation in grain Zinc (Zn) concentration in bread wheat germplasm derived from Watkins landraces

“…Approximately 10 grains of all 245 wheat genotypes in three replicates from Nottingham (n = 735) and in one replicate from Rothamsted site (n = 245) in 2015-16 were weighed and the grain samples were soaked in this solution, 3 mL 70% Trace Analysis Grade (TAG) HNO 3 and 2 mL hydrogen peroxide (H 2 O 2 ), overnight at room temperature. Grain was digested using a microwave system as described previously [9,26]. Briefly, this comprised a Multiwave 3000 platform with a 48-vessel MF50 rotor (Anton Paar Gmbh, Graz, Austria); digestion vessels were perfluoroalkoxy (PFA) tubes in polyethylethylketone (PEEK) pressure jackets (Anton Paar GmbH).…”

“…Modern wheat varieties typically have whole-grain Zn concentration less than the target of 40 mg kg -1 considered appropriate for human diets under field conditions in S. Asia [8]. For example, grain Zn concentration ranged from 25-35 mg kg -1 in a panel of 36 widely adapted Indian wheat genotypes under field conditions [9].…”

Enhancing Zinc Accumulation and Bioavailability in Wheat Grains by Integrated Zinc and Pesticide Application

“…Although the present soil was not Zn deficient (DTPA-Zn 0.91 mg kg −1 ) and grain yield was not affected by Zn applications, grain Zn in wheat plants without foliar Zn spray ranged from 29-34 mg kg −1 across years ( Figure 3). It is comparable to the global scale of 20 to 35 mg kg −1 [6,8,13,25,26], showing a solid gap to the biofortification target for human health (40-60 mg kg −1 ) [3,5,9]. By foliar Zn application, grain Zn concentration increased by 62%-81% in 2017 and by 80%-107% in 2018 than the control plants, respectively (Figure 3).…”