Identification of cadmium tolerant and sensitive genotypes of castor and their contrasting responses to cadmium treatment

Mitigating cadmium accumulation and toxicity in plants: The promising role of nanoparticles

Cadmium (Cd) is a highly toxic heavy metal that adversely affects humans, animals, and plants, even at low concentrations. It is widely distributed and has both natural and anthropogenic sources. Plants readily absorb and distribute Cd in different parts. It may subsequently enter the food chain posing a risk to human health as it is known to be carcinogenic. Cd has a long half-life, resulting in its persistence in plants and animals. Cd toxicity disrupts crucial physiological and biochemical processes in plants, including reactive oxygen species (ROS) homeostasis, enzyme activities, photosynthesis, and nutrient uptake, leading to stunted growth and reduced biomass. Although plants have developed defense mechanisms to mitigate these damages, they are often inadequate to combat high Cd concentrations, resulting in yield losses. Nanoparticles (NPs), typically smaller than 100 nm, possess unique properties such as a large surface area and small size, making them highly reactive compared to their larger counterparts. NPs from diverse sources have shown potential for various agricultural applications, including their use as fertilizers, pesticides, and stress alleviators. Recently, NPs have emerged as a promising strategy to mitigate heavy metal stress, including Cd toxicity. They offer advantages, such as efficient absorption by crop plants, the reduction of Cd uptake, and the enhancement of mineral nutrition, antioxidant defenses, photosynthetic parameters, anatomical structure, and agronomic traits in Cd-stressed plants. The complex interaction of NPs with calcium ions (Ca2+), intracellular ROS, nitric oxide (NO), and phytohormones likely plays a significant role in alleviating Cd stress. This review aims to explore the positive impacts of diverse NPs in reducing Cd accumulation and toxicity while investigating their underlying mechanisms of action. Additionally, it discusses research gaps, recent advancements, and future prospects of utilizing NPs to alleviate Cd-induced stress, ultimately promoting improved plant growth and yield.

Genome-wide identification of the NRAMP gene family in Populus trichocarpa and their function as heavy metal transporters

The natural resistance-associated macrophage protein (NRAMP) gene family plays a key role in essential mineral nutrient homeostasis, as well as toxic metal accumulation, translocation, and detoxification. Although the NRAMP family genes have been widely identified in various species, they still require to be analyzed comprehensively in tree species. In this study, a total of 11 NRAMP members (PtNRAMP1-11) were identified in Populus trichocarpa, a woody model plant, and further subdivided into three groups based on phylogenetic analysis. Chromosomal location analysis indicated that the PtNRAMP genes were unevenly distributed on six of the 19 Populus chromosomes. Gene expression analysis indicated that the PtNRAMP genes were differentially responsive to metal stress, including iron (Fe) and manganese (Mn) deficiency, as well as Fe, Mn, zinc (Zn), and cadmium (Cd) toxicity. Furthermore, the PtNRAMP gene functions were characterized using a heterologous yeast expression system. The results showed that PtNRAMP1, PtNRAMP2, PtNRAMP4, PtNRAMP9, PtNRAMP10, and PtNRAMP11 displayed the ability to transport Cd into yeast cells. In addition, PtNRAMP1, PtNRAMP6, and PtNRAMP7 complemented the Mn uptake mutant, while PtNRAMP1, PtNRAMP6, PtNRAMP7, and PtNRAMP9 complemented the Fe uptake mutant. In conclusion, our findings revealed the respective functions of PtNRAMPs during metal transport as well as their potential role in micronutrient biofortification and phytoremediation.