Advances in the Uptake and Transport Mechanisms and QTLs Mapping of Cadmium in Rice

Abstract

Cadmium (Cd), as a heavy metal, presents substantial biological toxicity and has harmful effects on human health. To lower the ingress levels of human Cd, it is necessary for Cd content in food crops to be reduced, which is of considerable significance for ensuring food safety. This review will summarize the genetic traits of Cd accumulation in rice and examine the mechanism of Cd uptake and translocation in rice. The status of genes related to Cd stress and Cd accumulation in rice in recent years will be summarized, and the genes related to Cd accumulation in rice will be classified according to their functions. In addition, an overview of quantitative trait loci (QTLs) mapping populations in rice will be introduced, aiming to provide a theoretical reference for the breeding of rice varieties with low Cd accumulation. Finally, existing problems and prospects will be put forward.

Breeding for low cadmium accumulation cereals

“…For developing low-Cd crop cultivars, it is important to identify genes related to Cd accumulation and to understand the mechanisms of Cd uptake and accumulation in plants. In recent years, a number of genes related to Cd transport in cereals have been identified (Table 1), and progress has been made in understanding the mechanisms of Cd uptake and transport (Chen JG et al, 2019). Cd is not essential for plant growth, but its transport in plants is mediated by the transporters for essential elements such as Zn, Mn, Ca, and Fe (Uraguchi and Fujiwara, 2013;Clemens and Ma, 2016).…”

“…In contrast to multiple-gene control, durum wheat grain Cd accumulation seems to be controlled List of reported genes in rice (Oryza sativa) related to Cd homeostasis was reviewed by Chen JG et al (2019). PVE: phenotypic variation explained; CSSL: chromosome segment substitution line; RFLP: restriction fragment length polymorphism; SSR: simple sequence repeat; BIL: backcross inbred line; RIL: recombinant inbred line; DH: doubled haploid; CAPS: cleaved amplified polymorphic sequence; SNP: single nucleotide polymorphism; STS: sequence tagged site by a single dominant gene, Cdu1, which was first found on a linkage group using the random amplified polymorphic DNA marker (OPC20) (Penner et al, 1995).…”

“…Tang et al (2017) and Liu SM et al (2019) demonstrated that it is feasible to generate yield-competitive and low-Cd rice lines through CRISPR/Cas9-mediated mutagenesis of OsNramp5, using the rice cultivars Huazhan and Xidao 1 as the parental wild-type lines. However, genetic modification does not always meet with favorable public perceptions (Chen JG et al, 2019;Chen KL et al, 2019).…”

“…List of reported genes in rice (Oryza sativa) related to Cd homeostasis was reviewed byChen JG et al (2019) …”

Univariate and Multivariate QTL Analyses Reveal Covariance Among Mineral Elements in the Rice Ionome

“…Identification of QTLs or genes that control the concentrations of essential mineral nutrients and toxic trace metals (also known as the ionome) in rice grains can increase the speed and efficiency of the variety improvement process. In the past few decades, many efforts have been made in mapping QTLs regulating the rice grain ionome, and hundreds of genetic loci have been identified for individual elements through bi-parental ( Norton et al, 2010 , 2019 ; Zhang et al, 2014 ; Yu et al, 2015 ; Chen et al, 2019 ; Raza et al, 2019 ; Liu et al, 2020 ; Wang et al, 2020 ) or genome wide association (GWA) mapping approaches ( Norton et al, 2014 ; Huang et al, 2015 ; Yang et al, 2018 ; Tan et al, 2020 ). Among these QTLs, only a small number of causal genes have been identified and functionally characterized, including OsHMA3 , OsCAL1 and OsCd1 for Cd ( Ueno et al, 2010 ; Miyadate et al, 2011 ; Luo et al, 2018 ; Sui et al, 2019 ; Yan et al, 2019 ), OsHMA4 for Cu ( Huang et al, 2016 ), and OsMOT1;1 for molybdenum (Mo) ( Yang et al, 2018 ; Huang et al, 2019 ; Wang et al, 2020 ).…”