Mutation at Different Sites of Metal Transporter Gene OsNramp5 Affects Cd Accumulation and Related Agronomic Traits in Rice (Oryza sativa L.)

Abstract

OsNramp5 is a key gene involved in the control of the uptake of Cd, Mn, and other metal ions by rice root cells. The functional deficiency of this gene can significantly reduce the accumulation of Cd in rice grains, but the effects of its mutation on agronomic traits such as yield and quality have not been investigated comprehensively yet. In the present study, three Huanghuazhan-based OsNramp5 mutants [LCH1 (Low Cadmium Huanghuazhan 1), LCH2 (Low Cadmium Huanghuazhan 2), and LCH3 (Low Cadmium Huanghuazhan 3)] were obtained using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) technology. The mutation-type analysis showed that LCH1, LCH2, and LCH3 encoded defective OsNramp5 protein sequences containing only 76aa, 176aa, and 266aa, respectively. The determination of metal content and the statistics of related agronomic traits revealed that the functionally deficient OsNramp5 not only significantly reduced the accumulation of Cd in the grains of the mutants but also affected rice yield and quality. However, with the decrease of OsNramp5 mutation degree, its effects on chlorenchyma Mn accumulation, yield, and quality were also diminished. Additionally, we also found that the increase in the concentration of Mn in the soil restored the phenotype of the declined yield and quality due to the functional deficiency of OsNramp5. Our findings provide novel insights into and new materials for breeding rice varieties with low Cd accumulation and excellent agronomic traits under severe Cd pollution environment.

Genome-Wide Identification of the Nramp Gene Family in Spirodela polyrhiza and Expression Analysis under Cadmium Stress

“…Therefore, we speculate that it is on the other way in plants, and it is consistent with the result of the current study. In the present study, the phylogenetic tree showed that the intron length of Nramp transporter genes increased with evolution in plants, whereas the intron number of EIN family remained almost unchanged (4)(5)(6)(7)(8). Similarly, the number of motifs of the Nramp transporter genes also increased through evolution in general while the number of motifs of EIN family remained stable.…”

“…Natural resistance-associated macrophage proteins (Nramps), which comprise a highly conserved gene family across all species, from bacteria to humans, and are identified as an integral membrane protein family, are critical proton/metal transporters in plants [1][2][3][4]. The genes of the Nramp transporter family play important roles in the transport of ions, such as Cd, Fe, Mn, and Zn [5][6][7][8][9][10]. In Arabidopsis thaliana, AtNramp1 is located in the plasma membrane and is identified as an Fe, Mn, and Cd transporter [11,12], whereas AtNramp2 is located in endomembrane and acts in the distribution of Mn between intracellular organelles [13,14].…”

Phytoremediation of Cadmium: Physiological, Biochemical, and Molecular Mechanisms

“…Genomics approaches' advancement enhances the identification of multiple genes involved in phytoremediation, plant stress tolerance, and transport of heavy metals, such as DNA mismatch repair (MMR) in a soybean cultivar [250], targeted induced local lesions in genomes (TILLING) in rapeseed [8], clustered regularly interspaced short palindromic repeats (CRISPER/Cas9) in rice [251], and genome-wide association studies (GWAS) in rapeseed [252,253].…”

“…CRISPER/Cas9 technology was used to obtain three mutants (LCH1, LCH2, and LCH3) of the OSNramp5 gene from rice that were involved in the uptake of Cd and other metal ions from root cells [ 251 ]. Tang et al [ 256 ] used the CRISPER/Cas9 system in the rice indica gene OsNramp5 to reduce Cd accumulation in rice for food safety, and demonstrated a 0.05 mg kg −1 decrease in the Cd concentration whereas the plant yield was not affected.…”

Cadmium isotope fractionation reveals genetic variation in Cd uptake and translocation by Theobroma cacao and role of natural resistance-associated macrophage protein 5 and heavy metal ATPase-family transporters

“…Such work has particularly focused on genes that encode either transporters, such as natural resistanceassociated macrophage proteins (NRAMPs) [18][19][20][21][22][23][24][25] , which mediate the entry of Cd from the rhizosphere, or those such as heavy metal ATPases (HMAs) [26][27][28][29][30][31][32] , which determine the deposition of Cd in vacuoles or its translocation in the plant. Significant findings include (i) that the level of NRAMP5 in rice may be linked to the higher uptake of Cd in this species than in maize 21 , (ii) combining knockout of one homeologous HMA4 gene (nonsense mutation) and reduction of the other (missense mutation) reduced Cd levels in tobacco, while maintaining plant vigour 27 , and (iii) the identification in wheat of HMA3 variants linked to reduced Cd accumulation 26 .…”