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The combined effect of iron (Fe) and zinc (Zn) starvation on their uptake and transportation and the molecular regulatory networks is poorly understood in wheat. To fill this gap, we performed a comprehensive physiological, biochemical and transcriptome analysis in two bread wheat genotypes, i.e. Narmada 195 and PBW 502, differing in inherent Fe and Zn content. Compared to PBW 502, Narmada 195 exhibited increased tolerance to Fe and Zn withdrawal by significantly modulating the critical physiological and biochemical parameters. We identified 25 core genes associated with four key pathways, i.e. methionine cycle, phytosiderophore biosynthesis , antioxidant and transport system, that exhibited significant up-regulation in both the genotypes with a maximum in Narmada 195. We also identified 26 microRNAs targeting 14 core genes across the four pathways. Together, core genes identified can serve as valuable resources for further functional research for genetic improvement of Fe and Zn content in wheat grain.

Wheat (T. aestivum L.) is the second most important staple food crop consumed in the form of various end-use products across the world. However, it contains lower concentrations of Fe and Zn leading to micronutrient deficiency in human beings where wheat is the sole diet. Therefore, increasing grain Fe/Zn content in wheat has become priority in wheat breeding programmes across the world. Understanding the molecular mechanism of Fe/Zn transport and accumulation in grains is required to expedite the breeding process. For this purpose, whole seedling transcriptome analysis was conducted in four wheat genotypes (CRP 1660, Sonora 64, Vinata, : high, and DBW17: low) differing in grain Fe/Zn content under controlled and Fe/Zn deficient conditions. Twenty eight key transcripts involved in phytosiderophore biosynthesis, Fe/Zn uptake and transport were identified. Expression analysis of 12 of the transcripts using qPCR was conducted in seedling stage and flag leaf which exhibited greater differential accumulation in CRP 1660 followed by Vinata, Sonora 64 and DBW 17 in both flag leaf and seedling. However, there was significantly higher differential accumulation of the transcripts in flag leaf as compared to seedling. In CRP 1660, transcripts pertaining to phytosiderophore biosynthesis like DMAS1-B, NRAMP2 and NAAT2-D showed greater accumulation. Additionally, corresponding miRNAs were also identified for these 28 transcripts. The findings will help in better understanding of molecular basis of Fe/Zn transport and accumulation in grain and subsequent utilization in breeding to improve Fe/Zn content in wheat grain.

In plants, iron (Fe) & zinc (Zn) uptake and transportation from the rhizosphere to the grain is a critical process regulated by complex transcriptional regulatory networks. However, understanding the combined effect of Fe & Zn starvation on their uptake and transportation and the molecular regulatory networks that control them lack in wheat. Here, we performed a comprehensive physiological, biochemical and transcriptome analysis in two bread wheat genotypes,i.e.Narmada 195 and PBW 502, differing in inherent Fe & Zn content to understand the mechanism of Fe & Zn homeostasis. Compared to PBW 502, Narmada 195 exhibited increased tolerance to Fe & Zn withdrawal by an increased level of antioxidant enzymes and DPPH radical scavenging activity along with less malondialdehyde (MDA), H2O2level, increased PS accumulation and lower reduction of root and shoot Fe & Zn content and length, leaf chlorosis, and leaf area. By integrating physiological and biochemical data along with co-expression & functional genome annotation and gene expression analysis, we identified 25 core genes associated with four key pathways,i.e.Met cycle (10), PS biosynthesis (4), antioxidant (3) and transport system (8) that were significantly modulated by Fe & Zn withdrawal in both the genotypes. Genes of these four pathways were more considerably up-regulated in Narmada 195, allowing better tolerance to Fe & Zn withdrawal and efficient uptake and transportation of Fe & Zn. Chromosomal distribution and sub-genome wise mapping of these genes showed a contribution from all the chromosomes except group 5 chromosomes with the highest number of genes mapped to chromosome 4 (24%) and sub-genome D (40%). Besides, we also identified 26 miRNAs targeting 14 core genes across the four pathways. Together, our work provides a crucial angle for an in-depth understanding of regulatory cross-talk among physiological, biochemical and transcriptional reprogramming underlying Fe & Zn withdrawal in wheat. Core genes identified can serve as valuable resources for further functional research for genetic improvement of Fe & Zn content in wheat grain.HighlightOur work provides a crucial angle for a comprehensive understanding of the regulatory mechanism underlying Fe & Zn withdrawal associated with physiological, biochemical and transcriptional reprogramming in wheat.

The datasets depicted in the paper are related to the original article entitled “Identifying transcripts associated with efficient transport and accumulation of Fe and Zn in hexaploid wheat (T. aestivum L.)” [1] . Four wheat genotypes i.e. Sonora 64, CRP 1660, Vinata, and DBW 17 were selected for RNA sequencing using Illumina HiSeq4000 platform. These genotypes were grown in Fe/Zn sufficient and deficient conditions in sand pot culture with intermittent administration of Hoagland solution. Pooled assembly was carried out for all of the four varieties subsequent to discarding low-quality reads, adaptor sequences and contamination resulting in approximately 315,904 clean transcripts of around 937 bp lengths and N50 of 1,294 bp. For the functional annotation of the identified transcripts databases like Pfam, KEGG pathway, Uniprot, PlnTFDB and wheat proteins were utilized. Differential expression calculation of transcripts was carried out by DESeq, an R package and real-time PCR study of 12 Fe/Zn metabolic pathway related transcripts was utilized for further revalidation of data. Elemental analysis of grain Fe and Zn was performed using Flame Atomic Absorption Spectrometry (FAAS). The RNA-seq data of all the four wheat genotypes was uploaded on Sequence Read Archive (SRA: SUB6961770 and BioProject: PRJNA605909), enabling easy access to the researchers worldwide.

The considerable amount of genetic variability on the basis of GCV and PCV estimates for the traits; days to 50% flowering, numbers of primary and secondary branches per plant, length of siliqua, 1000-seed weight, seed yield per plant, biological yield per plant and harvest index were found in thirty five genotypes of Indian mustard (Brassica juncea L. Czern and Coss). Heritability and genetic advance were higher for days to 50% flowering, plant height and biological yield per plant. Although, number of secondary branches per plant, seed yield per plant and harvest index had moderately high heritability with moderate genetic advance indicating additive gene effects and selection pressure could be applied on them for yield improvement leads to fast genetic improvement of the materials. Days to 75% maturity, length of siliqua, 1000-seed weight and oil content had low heritability indicating that these traits were under the influence of environmental factors and selection on the basis of these traits could not be effective.

Soil salinity is major constraint for wheat production globally and breeding wheat cultivars for salt tolerance by conventional means is difficult. Therefore, understanding molecular components associated with salt tolerance is needed to facilitate breeding for salt tolerance in wheat. In this investigation, quantitative trait loci (QTL/s) associated with salt tolerance were identified using recombinant inbred lines (RILs) developed from a cross between Kharchia 65 (KH 65) and HD 2009 cultivars. Parents and RILs were evaluated under controlled and sodic stress conditions for 11 morpho-physiological and yield determining traits for two consecutive crop cycles. Simple sequence repeat (SSR) markers were employed for mapping studies. Using composite interval mapping approach, 11 QTLs on 6 chromosomal regions (1B, 2D, 5D, 6A, 6B and 7D) for 7 different traits were identified explaining proportion of the phenotypic variance (PVEs) (2.5–12.8%) under control condition. Three of the QTLs (QCph.iiwbr-2D.1, QCle.iiwbr-6A and QCle.iiwbr-6B) were most consistent in all the environments and explained PVEs (5.1–12.8%) under control condition. Twenty-five QTLs were detected on 7 chromosomal regions (1A, 1B, 2D, 4D, 5D, 6A and 7D) for 10 different traits explaining PVEs (2.6–15.1%) under salt stress. Six of the QTLs namely QSNa+.iiwbr-1B, QSK+.iiwbr-2D, QStn.iiwbr-4D, QSph.iiwbr-2D.1, QSph.iiwbr-6A and QSdth.iiwbr-2D were consistently reproducible in all the environments and explained PVEs ranging from 2.6 to 15.1%. SSR markers namely gwm 261, wmc 112, and cfd 84 were tightly linked with QTLs for K+ content; DTH and DTA; and TN and NE, respectively. Several QTLs contributing towards salt tolerance were present on 2D chromosome. Most of the QTLs linked with salt tolerant traits were inherited from KH 65 signifying the presence of several genes associated with salt tolerance in this cultivar. The information is very useful in marker assisted breeding to enhance salt tolerance in wheat.

A significant magnetocaloric effect (MCE) has been revealed in our investigation on polycrystalline Nd0.5Dy0.5FeO3 below 30 K. Observed magnetization of the system at low temperature is 32% higher than the expected average magnetization of NdFeO3 and DyFeO3. Such an enhancement in the magnetization led to a large change in magnetic entropy (10.4 Jkg-1 K-1) at 4 K. The observed entropy change is remarkable considering the higher natural abundance of Nd compared to that of Dy and negligible MCE seen in case of NdFeO3. Theoretical calculations performed using mean-field approximation and Monte Carlo simulations on an Ising type spin model indicate that the high magnetocaloric effect is caused primarily by the ordering of rare-earth ions in C-type antiferromagnetic state in presence of molecular exchange field created by Fe ions.