New insights into root cell contributions to cadmium accumulation in water spinach

Cadmium (Cd) accumulation in crops poses a serious risk to human health, particularly through contaminated food chains. In water spinach (Ipomoea aquatica), a widely cultivated vegetable, the capacity for Cd uptake varies among cultivars. This study identifies key differences between two cultivars, QLQ (low-Cd accumulation) and T308 (high-Cd accumulation), by analyzing their root cell types at the molecular level. Single-cell RNA sequencing (scRNA-seq) was employed to explore how specific root cells contribute to Cd fixation and transport, providing new insights into the plant's ability to handle Cd toxicity.

Cadmium (Cd) pollution is a growing environmental concern, affecting agricultural systems worldwide. In plants, Cd accumulates mainly in the roots, but how it is processed and transported to other plant parts remains poorly understood. Water spinach is particularly susceptible to Cd uptake, and its cultivars exhibit varying levels of accumulation. This study focuses on the role of root cell types in regulating Cd fixation and translocation, using state-of-the-art single-cell sequencing technologies to analyze these processes at a molecular level. Given the complexity of plant response to heavy metals, further in-depth research is crucial to identify mechanisms for breeding crops with reduced Cd accumulation.

Published (DOI: 10.1093/hr/uhaf077) in Horticulture Research, this study by researchers from Hunan Institute of Technology and Hunan Chemical Vocational Technology College investigates the molecular mechanisms behind Cd accumulation in Ipomoea aquatica. By comparing the root cell responses of the low-Cd QLQ and high-Cd T308 cultivars, the research explores the unique gene expression profiles of root cells and how these differences influence Cd uptake and transport.

The study used scRNA-seq to identify nine distinct cell types in the root tips of both cultivars. Significant differences in gene expression were observed, particularly in the epidermis, cortex, and xylem. The QLQ cultivar exhibited higher expression of genes associated with lignin deposition, such as LAC2 and PER72, which help fix Cd in the cell wall and limit its movement to the shoot. In contrast, T308 showed elevated expression of hormone-related genes like PIN1 and ARF8, which may enhance xylem development and Cd transport. This study also examined the structural differences in the root cells, revealing that lignin content and pectin methylation play critical roles in the differential accumulation of Cd between cultivars. The findings highlight the complexity of root cell interactions with Cd, offering insights into potential strategies to reduce Cd uptake in crops.

"Understanding how different root cell types contribute to Cd uptake and transport opens the door for developing crops that can better handle contaminated soils," said Dr. Ying-Ying Huang, a lead researcher in the study. "This knowledge could be pivotal in designing pollution-safe cultivars to mitigate the health risks posed by cadmium in food."

The implications of this research extend to agriculture and food safety. By identifying the root mechanisms behind Cd accumulation, the study paves the way for breeding water spinach cultivars with lower Cd uptake. This could reduce the health risks associated with heavy metal contamination in crops and inform agricultural practices aimed at producing safer, more resilient food. Furthermore, the insights into lignin and pectin's roles in metal fixation could lead to broader applications in other crops, helping to address global concerns about soil contamination and food safety.

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References

DOI

10.1093/hr/uhaf077

Original Source URL

https://doi.org/10.1093/hr/uhaf077

Funding information

This study was supported by the National Natural Science Foundation of China (Grant No. 42107039 and 42007144), Natural Science Foundation of Hunan Province, China (Grant No. 2022JJ40139), Scientific Research Foundation of Hunan Provincial Education Department (Grant No. 24B0838) and College Students Research Learning and Innovative Experiment Project of Hunan Province (Grant No. S202311528145).

About Horticulture Research

Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.