The Road to Practical Application of Cadmium Phytoremediation Using Rice

Abstract

Cadmium (Cd) is a toxic heavy metal that causes severe health issues in humans. Cd accumulates in the human body when foods produced in Cd-contaminated fields are eaten. Therefore, soil remediation of contaminated fields is necessary to provide safe foods. Rice is one of the primary candidates for phytoremediation. There is a genotypic variation of Cd concentration in the shoots and grains of rice. Using the world rice core collection, ‘Jarjan’, ‘Anjana Dhan’, and ‘Cho-ko-koku’ were observed with a significantly higher level of Cd accumulation in the shoots and grains. Moreover, OsHMA3, a heavy metal transporter, was identified as a responsive gene of quantitative trait locus (QTL) for high Cd concentration in the shoots of these three varieties likewise. However, it is difficult to apply practical phytoremediation to these varieties because of their unfavorable agricultural traits, such as shatter and easily lodged. New rice varieties and lines were bred for Cd phytoremediation using OsHMA3 as a DNA marker selection. All of them accumulated Cd in the shoots equal to or higher than ‘Cho-ko-koku’ with improved cultivation traits. Therefore, they can be used for practical Cd phytoremediation.

The E3 Ubiquitin Ligase Gene Sl1 Is Critical for Cadmium Tolerance in Solanum lycopersicum L.

“…Despite the fact that CAXs are mostly Ca 2+ specific transporters, AtCAX2 and AtCAX4 have been demonstrated to transport various other metals, such as Cd, Zn, and Mn in Arabidopsis [58]. Similarly, Fe-specific transporter OsIRT1 has been found to participate in Cd uptake in rice [63]. Thus, suppression of the metal transporter may lead to essential nutrient deficiency and compromised plant growth.…”

Genetic Regulation Mechanism of Cadmium Accumulation and Its Utilization in Rice Breeding

“…At present, three strategies can be employed to reduce Cd accumulation in rice grains ( Figure 2 ) [ 98 ]. These strategies include (1) Cd regulation through agronomical measures such as soil improvement [ 99 ], water-fertilizer control [ 100 , 101 ], tillage management [ 102 ], and adding or spraying exogenous substances, mainly silicon [ 103 ], and abscisic acid [ 104 ]); (2) bioremediation to reduce the Cd concentration in the soil or reducing the Cd content in rice grains through phyto-treatment [ 105 ] and microbiological treatments [ 106 ]; and (3) screening and breeding rice varieties with low Cd accumulation. However, agronomical measures and bioremediation are often faced with many problems such as the high investment cost, slow efficiency, high labor requirement, and difficulty preventing and controlling subsequent pollution.…”

Morphological responses of six sorghum varieties on cadmium-contaminated soil

“…Most morphological traits in sorghum are linked to one or more economically important traits and will aid in selecting high-yielding sorghum genotypes (Mufumbo et al 2022). Plants suitable for phytoremediation must have several characteristics, including the capability of accumulating heavy metals above ground, tolerance to metal accumulation, fast growth and high biomass, branched root system, and ease of harvest (Eapen and D'Souza 2005;Sarma 2011;Muro-González et al 2020), easy cultivation and quick harvest (Takahashi et al 2021), not consumed by humans (Jia et al 2016;Martiwi et al 2020;Muro-González et al 2020), has rejection of herbivores to avoid contamination of the food chain (Huang et al 2020), has several economic interests (Abdel-Sabour et al 2000;Almodares and Darany 2006;Angelova et al 2011;Liu et al 2020;Saleem et al 2020). Futhermore, the six varieties were able to adapt to cadmium-contaminated land.…”