Hu Xiaoting, Li Tao, Xu Weihong, Chai Yourong
College of Resources and Environmental Sciences, Southwest University, Chongqing 400715, PR China.
College of Resources and Environmental Sciences, Southwest University, Chongqing 400715, PR China.
Ecotoxicol Environ Saf. 2021 Mar 30;216:112182. doi: 10.1016/j.ecoenv.2021.112182.
Cadmium (Cd) tolerance mechanisms in plant are mainly divided into two categories: evasion mechanism and tolerance mechanism. However, due to the complexity of the mechanism of Cd absorption and accumulation in crops, there are still disputes and controversies about Cd toxicity to plants and the mechanism of Cd tolerance in plants. The Cd absorption and accumulation mechanism in edible parts of pepper remains unknown. The present study characterized three pepper cultivars with different cadmium tolerance under cadmium stress. One high-Cd-accumulation type (X55), a medium-Cd-accumulation type (Daguo 99) and a low-Cd-accumulation type (Luojiao 318) were selected to study distribution characteristics of Cd in subcellular fractions of the three pepper varieties as well as expression difference of key Cd accumulation and tolerance genes under different cadmium levels. The results showed that under Cd stress, X55 and Daguo 99 mainly migrated Cd from root to stems and leaves, while Luojiao318 migrated it to the fruit. The Cd concentration in the subcellular fractions of pepper roots, stems, leaves and fruits was as follow: cell wall (F1) > organelle (F2) > cell soluble fraction (F3). The roots, stems and leaf cells of X55 have strong Cd compartmentalization capacity. The fruit cells of Daguo 99 have strong Cd compartmentalization capacity, while the roots of Luojiao318 have strong ability to inhibit Cd absorption. Under Cd stress, HMA1, HMA2 and NRAMP1-6 were up-regulated in roots, stems and fruits of the three varieties. FTP1-2 and FTP1-3 genes were significantly up-regulated in different materials, except the roots of Daguo 99. Under Cd treatment, PCS gene expression of pepper showed an order of that of X55 > Luojiao 318 >Daguo 99. The present study revealed that the cell wall of pepper played an important role in Cd separation and resistance. The difference in Cd accumulation ability of the pepper varieties may be related to differences in main expression sites and expression levels of HMA, NRAMP, FTP and PCS genes.
植物中镉（Cd）的耐受机制主要分为两类：规避机制和耐受机制。然而，由于作物对镉吸收和积累机制的复杂性，关于镉对植物的毒性以及植物对镉的耐受机制仍存在争议。辣椒可食用部分的镉吸收和积累机制尚不清楚。本研究对镉胁迫下三种镉耐受性不同的辣椒品种进行了表征。选择一种高镉积累型（X55）、一种中镉积累型（大国99）和一种低镉积累型（洛椒318），研究三种辣椒品种亚细胞组分中镉的分布特征以及不同镉水平下关键镉积累和耐受基因的表达差异。结果表明，在镉胁迫下，X55和大国99主要将镉从根部转移到茎和叶，而洛椒318则将其转移到果实中。辣椒根、茎、叶和果实亚细胞组分中的镉浓度顺序为：细胞壁（F1）＞细胞器（F2）＞细胞可溶性组分（F3）。X55的根、茎和叶细胞具有较强的镉区室化能力。大国99的果实细胞具有较强的镉区室化能力，而洛椒318的根具有较强的抑制镉吸收的能力。在镉胁迫下，三个品种根、茎和果实中的HMA1、HMA2和NRAMP1 - 6均上调。除大国99的根外，FTP1 - 2和FTP1 - 3基因在不同材料中均显著上调。镉处理下，辣椒PCS基因表达表现为X55＞洛椒318＞大国99。本研究表明，辣椒细胞壁在镉的分离和抗性中起重要作用。辣椒品种镉积累能力的差异可能与HMA、NRAMP、FTP和PCS基因的主要表达位点和表达水平差异有关。
