Identification of subspecies-divergent genetic loci responsible for mineral accumulation in rice grains

Unveiling molecular mechanisms of iron and zinc dynamics in rice

Iron (Fe) and zinc (Zn) are essential micronutrients critical for human health, yet their deficiencies are widespread, particularly in rice-dependent populations. Rice, a staple food for over half the global population, lacks sufficient bioavailable Fe and Zn in its grains, contributing to global malnutrition. This review delves into the molecular mechanisms governing Fe and Zn transport in rice, focusing on gene families such as IRT, YSL, ZIP, and HMA, which regulate uptake, translocation, and storage. These transporters exhibit intricate interactions and crosstalk, influenced by environmental factors and shared pathways, underscoring the complexity of Fe-Zn homeostasis. Biofortification, through genetic engineering and conventional breeding, emerges as a promising solution to address Fe and Zn deficiencies. Genetic strategies include overexpression of ferritin and nicotianamine synthase genes, alongside manipulation of metal transporter genes, to enhance micronutrient accumulation in rice grains. The advanced breeding approaches including marker-assisted selection and quantitative trait loci (QTL) mapping, complement genetic engineering, offering non-transgenic alternatives for micronutrient enhancement. The common challenges such as regulatory barriers, public perception, and trait stability under diverse conditions necessitate interdisciplinary collaboration and technological advancements.

Genome-wide association study reveals genetic loci for ten trace elements in foxtail millet (Setaria italica)

KEY MESSAGE

One hundred and fifty-five QTL for trace element concentrations in foxtail millet were identified using a genome-wide association study, and a candidate gene associated with Ni-Co-Cr concentrations was detected. Foxtail millet (Setaria italica) is an important regional crop known for its rich mineral nutrient content, which has beneficial effects on human health. We assessed the concentrations of ten trace elements (Ba, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, and Zn) in the grain of 408 foxtail millet accessions. Significant differences in the concentrations of five elements (Ba, Co, Ni, Sr, and Zn) were observed between two subpopulations of spring- and summer-sown foxtail millet varieties. Moreover, 84.4% of the element pairs exhibited significant correlations. To identify the genetic factors influencing trace element accumulation, a comprehensive genome-wide association study was conducted, identifying 155 quantitative trait locus (QTL) for the ten trace elements across three different environments. Among them, ten QTL were consistently detected in multiple environments, including qZn2.1, qZn4.4, qCr4.1, qFe6.3, qFe6.5, qCo6.1, qPb7.3, qPb7.5, qBa9.1, and qNi9.1. Thirteen QTL clusters were detected for multiple elements, which partially explained the correlations between elements. Additionally, the different concentrations of five elements between foxtail millet subpopulations were caused by the different frequencies of high-concentration alleles associated with important marker-trait associations. Haplotype analysis identified a candidate gene SETIT_036676mg associated with Ni accumulation, with the GG haplotype significantly increasing Ni-Co-Cr concentrations in foxtail millet. A cleaved amplified polymorphic sequence marker (cNi6676) based on the two haplotypes of SETIT_036676mg was developed and validated. Results of this study provide valuable reference information for the genetic research and improvement of trace element content in foxtail millet.