Knockout of OsNramp5 using the CRISPR/Cas9 system produces low Cd-accumulating indica rice without compromising yield

Abstract

Rice grain with excessive cadmium (Cd) is a major source of dietary Cd intake and a serious threat to health for people who consume rice as a staple food. The development of elite rice cultivars with consistently low Cd content is challenging for conventional breeding approaches, and new strategies urgently need to be developed. Here, we report the development of new indica rice lines with low Cd accumulation and no transgenes by knocking out the metal transporter gene OsNramp5 using CRISPR/Cas9 system. Hydroponic culture showed that Cd concentrations in shoots and roots of osnramp5 mutants were dramatically decreased, resulting in rescue of impaired growth in high Cd condition. Cd-contaminated paddy field trials demonstrated that Cd concentration in osnramp5 grains was consistently less than 0.05 mg/kg, in contrast to high Cd concentrations from 0.33 mg/kg to 2.90 mg/kg in grains of Huazhan (the wild-type indica rice). In particular, the plant yield was not significantly affected in osnramp5 mutants. Furthermore, we developed promising hybrid rice lines with extremely low Cd content in grains. Our work supplies a practical approach to developing Cd pollution-safe indica rice cultivars that minimizes Cd contamination risk in grains.

Developing disease‐resistant thermosensitive male sterile rice by multiplex gene editing

“…For instance, using the CRISPR/Cas9 to introduce a loss‐of‐function mutation into the Waxy gene reduced the amylose content and generated new glutinous rice (Zhang et al ). Knocking out the metal transporter gene OsNramp5 using CRISPR/Cas9 system produces low Cd‐accumulating indica rice without compromising yield (Tang et al ). CRISPR/CAS9‐mediated editing of the fragrant gene BADH2 in rice reduced the Badh2 RNA level and increased 2‐acetyl‐1‐pyrroline content in the mutant (Shao et al ).…”

Development of nutritious rice with high zinc/selenium and low cadmium in grains through QTL pyramiding

“…There are several biotechnological approaches to decrease Cd in rice grain. Knockout of OsNRAMP5, a major transporter for Mn and Cd uptake in rice, could produce very low Cd‐accumulating rice (Sasaki et al 2012; Tang et al 2017). However, OsNRAMP5 knockout plants have a potential risk of Mn deficiency under low Mn supply conditions because of shortages of Mn uptake (Sasaki et al 2012; Yang et al 2019).…”

Epigenetic Footprints of CRISPR/Cas9-Mediated Genome Editing in Plants

“…Off-target mutation is a common and critical problem associated with CRISPR/Cas9-mediated genome editing in human cells, but it has rarely been reported in gene-edited plants. Several studies have reported that there was no offtarget mutation, not only in Arabidopsis, but also various crop species Pan et al, 2016;Braatz et al, 2017;Jia et al, 2017;Tang et al, 2017;Cai et al, 2018). We analyzed the potential off-target mutagenesis on loci highly similar to the target sequence.…”