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Wheat crop grown under elevated CO 2 (EC) often have a lowered grain nitrogen (N) and protein concentration along with an altered grain ionome. The mechanistic understanding on the impact of CO 2 x N interactions on the grain ionome and the expression of genes regulating grain ionome is scarce in wheat. In the present study, the interactive effect of EC and N dosage on grain yield, grain protein, grain ionome, tissue nitrate, and the expression of genes contributing to grain ionome (TaNAM-B1 and TaYSL6) are described. Three bread wheat genotypes were evaluated under two CO 2 levels (Ambient CO 2 (AC) of 400 ± 10 ppm and elevated CO 2 (EC) of 700 ± 10 ppm) and two N levels (Low (LN) and Optimum N (ON). In EC, wheat genotypes HD2967 and HI 1500 recorded a significant decrease in grain nitrate content, while leaf and stem nitrate showed a significant increase. BT. Schomburgk (BTS), showed a significant increase in unassimilated nitrate and a decline in grain N and grain protein under EC. There was a general decline of grain ionome (N, P, K, Ca, Fe) in EC, except for grain Na content. The expression of genes TaNAM-B1 and TaYSL6 associated with protein and micronutrient remobilization to grains during senescence were affected by both EC and N treatments. For instance, in flag leaves of BTS, the expression of TaNAM-B1 and TaYSL6 were lower in EC-LN compared to AC-LN. In maturing spikes, transcript abundance of TaNAM-B1 and TaYSL6 were lower in EC in BTS. The altered transcript abundance of TaYSL6 and TaNAM-B1 in source and sink supports the change in grain ionome and suggests an N dependent transcriptional reprogramming in EC. • Genotype BT. Schomburgk (BTS), showed a significant increase in unassimilated nitrate and a decline in grain N and grain protein under EC. • There was a general decline of grain ionome (N, P, K, Ca, Fe) in EC, except for grain Na content. • The expression of genes TaNAM-B1 and TaYSL6 associated with protein and micronutrient remobilization was reduced by EC in source and sink tissues. [ABSTRACT FROM AUTHOR]

The ionome of the rice grain is crucial for the health of populations that consume rice as a staple food. However, the contribution of phenotypic plasticity to the variation of rice grain ionome and the genetic architecture of phenotypic plasticity are poorly understood. In this study, we investigated the rice grain ionome of a rice diversity panel in up to eight environments. A considerable proportion of phenotypic variance can be attributed to phenotypic plasticity. Then, phenotypic plasticity and mean phenotype were quantified using Bayesian Finlay-Wilkinson regression, and a significant correlation between them was observed. However, the genetic architecture of mean phenotype was distinct from that of phenotypic plasticity. Also, the correlation between them was mainly attributed to the phenotypic divergence between rice subspecies. Furthermore, the results of whole-genome regression analysis showed that the genetic loci related to phenotypic plasticity can explain a considerable proportion of the phenotypic variance in some environments, especially for Cd, Cu, Mn, and Zn. Our study not only sheds light on the genetic architecture of phenotypic plasticity of the rice grain ionome but also suggests that the genetic loci which related to phenotypic plasticity are valuable in rice grain ionome improvement breeding.

The ionome of the rice grain is crucial for the health of populations that consume rice as a staple food. However, the contribution of phenotypic plasticity to the variation of rice grain ionome and the genetic architecture of phenotypic plasticity are poorly understood. In this study, we investigated the rice grain ionome of a rice diversity panel in up to eight environments. A considerable proportion of phenotypic variance can be attributed to phenotypic plasticity. Then, phenotypic plasticity and mean phenotype were quantified using Bayesian Finlay-Wilkinson regression, and a significant correlation between them was observed. However, the genetic architecture of mean phenotype was distinct from that of phenotypic plasticity. Also, the correlation between them was mainly attributed to the phenotypic divergence between rice subspecies. Furthermore, the results of whole-genome regression analysis showed that the genetic loci related to phenotypic plasticity can explain a considerable proportion of the phenotypic variance in some environments, especially for Cd, Cu, Mn, and Zn. Our study not only sheds light on the genetic architecture of phenotypic plasticity of the rice grain ionome but also suggests that the genetic loci which related to phenotypic plasticity are valuable in rice grain ionome improvement breeding. [ABSTRACT FROM AUTHOR]

Summary: Dissection of the genetic basis of wheat ionome is crucial for understanding the physiological and biochemical processes underlying mineral accumulation in seeds, as well as for efficient crop breeding. Most of the elements essential for plants are metals stored in seeds as chelate complexes with phytic acid or sulfur‐containing compounds. We assume that the involvement of phosphorus and sulfur in metal chelation is the reason for strong phenotypic correlations within ionome. Adjustment of element concentrations for the effect of variation in phosphorus and sulfur seed content resulted in drastic change of phenotypic correlations between the elements. The genetic architecture of wheat grain ionome was characterized by quantitative trait loci (QTL) analysis using a cross between durum and wild emmer wheat. QTL analysis of the adjusted traits and two‐trait analysis of the initial traits paired with either P or S considerably improved QTL detection power and accuracy, resulting in the identification of 105 QTLs and 617 QTL effects for 11 elements. Candidate gene search revealed some potential functional associations between QTLs and corresponding genes within their intervals. Thus, we have shown that accounting for variation in P and S is crucial for understanding of the physiological and genetic regulation of mineral composition of wheat grain ionome and can be implemented for other plants. Significance Statement: Many of the elements essential for plants are metals stored in seeds as chelate complexes with phytic acid or sulfur‐containing compounds. Adjustment for variation in P and S drastically change phenotypic associations within the ionome and considerably improve QTL detection power and accuracy. Therefore, we propose that this adjustment is crucial for the understanding of the physiological and genetic regulation of mineral composition of the wheat grain ionome, as well as for studies in other plant species. [ABSTRACT FROM AUTHOR]

Climate changes impose adoption of water-saving techniques to improve the sustainability of irrigated rice systems. This study was aimed, by a two-years side-by-side comparison, at verifying the hypothesis whether “Alternate Wetting and Drying” (AWD) affects the concentrations of health-related compounds and minerals in brown grains of three japonica rice (Oryza sativa L.) cvs (‘Baldo’, ‘Gladio’, and ‘Loto’) usually grown in temperate areas in continuous flooding (CF). Due to the rotational turns in water distribution imposed by local authorities and to the weather behavior, different AWD timing and severity occurred in the two years of the study. AWD induced in both seasons yield losses in ‘Baldo’ and ‘Gladio’ but not in ‘Loto’. In the brown grains of ‘Loto’, AWD increased the concentrations of total tocols, γ-oryzanol, flavonoids, and the antioxidant activity. AWD affected the concentrations of minerals, particularly increasing copper, cadmium and nickel, and decreasing manganese, arsenic and zinc. In the sensitive cultivars, ‘Baldo’ and ‘Gladio’, AWD seems to affect plant yield, rather than for severity of the dry period, for prolonged absence of ponded water that exposes plants to cooler temperatures. The selection of suitable cultivars, like ‘Loto’, tolerant to AWD-related stresses, could combine environmental, yield-related, and nutritional benefits improving the product quality.

• A declining grain density of Fe and Zn in cultivars of rice and wheat in past 50 years in India. • Newer-released (1990s and later) cultivars were stubborn to Fe and Zn application. • Application of one element had inhibitory effect on accumulation of the other. • Such inhibitory effect was magnified along succeeding decades since green revolution. Zinc and iron deficiency is a serious global health problem in humans depending on cereal-diet and is largely prevalent in low-income countries like Sub-Saharan Africa, and South and South-east Asia. We report inefficiency of modern-bred cultivars of rice and wheat to sequester those essential nutrients in grains as the reason for such deficiency and prevalence. To substantiate, experiments were conducted with elite, high-yielding cultivars of rice (n = 16) and wheat (n = 18) released in succeeding decades since the beginning of green revolution in India. The inherent Zn and Fe sequestering capacity in grains of the cultivars, and their responses to external application of Zn and Fe fertilizers were evaluated following standard protocols. We found a downward trend in grain density of Zn and Fe in those cereals in past more than 50 years. However, we failed to notice yield-dilution as a causative effect for such unwitting downward trend. With time, the cultivars again became stubborn to Zn and Fe fertilization for enhancing their grain density. Further, we noticed that external supply of one element, to improve its density in grains, had inhibitory effect on accumulation of the other, and the effect was magnified along the succeeding decades. Our innovative research warrants an improvement in ionomes of the cereals to alleviate the said incapacitating effect and ultimately the deficiency of those elements in humans, particularly living in low-income countries. [ABSTRACT FROM AUTHOR]

Salt-affected soils constrain wheat production globally. A wild wheat species, Thinopyrum bessarabicum (Savul. & Rayss) Á. Löve (Poaceae), and its derivatives are tolerant of high external NaCl concentrations but have not been tested yet in field conditions. The aim of this study was to study the performance of amphidiploids derived from T. bessarabicum for grain yield (GYD), yield components and grain mineral composition traits under normal and saline soil conditions. Field experiments were conducted at Karnal (pH(water) = 7.3) and Hisar (pH(water) = 8.3) sites in 2014–2015 and 2015–2016 in India. Grain samples were analysed using inductively coupled plasma–mass spectrometry (ICP-MS). Yield and yield component traits of amphidiploids were typically greater at Karnal than Hisar. The GYD was greater at Karnal (1.6 t ha−1) than Hisar (1.2 t ha−1) in 2014–2015. However, GYD was greater at Hisar (1.7 t ha−1) than Karnal (1.1 t ha−1) in 2015–2016. Mean grain zinc (Zn) concentration of eight amphidiploids, averaged across sites and years, varied from 36 to 43 mg kg−1. Some amphidiploids derived from T. bessarabicum showed greater GYD and grain Zn concentration under saline soils (Hisar) than normal soils (Karnal). These might be potential new sources for the development of salt-tolerant wheat varieties with increased grain Zn concentration under salt-affected soils. [ABSTRACT FROM AUTHOR]