Widespread heavy metal pollution in soils has posed serious threat to vegetable production and food security, yet little is still known about heavy metal accumulation and distribution in the majority of vegetable crops. Here, we report the generation of a tissue atlas of cadmium accumulation in zucchini (Cucurbita pepo var. Giromontial), a globally important cucurbit crop, based on two-season experiment with six genotypes grown under cadmium contaminated soils. Plant growth and development as manifested by biomass, flowering time and plant architecture were unaffected by 10 mg/kg cadmium treatment, but high level of cadmium enrichment was detected in all genotypes. Roots accumulated the largest amount of cadmium, whereas the cadmium concentrations in fruits was also considerable. The exocarps of fruits possessed nearly half of the total cadmium in fruits, rendering it a “hotspot” of safety risk. Measurement of the thiol-containing chelates revealed that concentration of GSH but not PCs was correlated with the cadmium concentration in subdivided fruit tissues, suggesting a mechanism of phloem-specific transportation of cadmium in the form of Cd-GSH. Based on the collective data, a tentative model describing the relationship between long-distance phloem transport and cadmium distribution in sink organs is proposed. The implications for food safety are discussed.

土壤中广泛存在的重金属污染对蔬菜生产和粮食安全构成了严重威胁，但对大多数蔬菜作物中重金属的积累和分布仍知之甚少。在这里，我们报告了西葫芦中镉积累的组织图谱的生成（Cucurbita pepo var. Giromontial)，一种全球重要的葫芦科作物，基于在镉污染土壤下生长的六种基因型的两季试验。以生物量、开花时间和植物结构表现的植物生长和发育不受 10 mg/kg 镉处理的影响，但在所有基因型中都检测到高水平的镉富集。根系积累了最多的镉，而果实中的镉浓度也相当可观。水果外果皮的镉含量占水果总镉的近一半，使其成为安全风险的“热点”。含硫醇螯合物的测量表明，GSH 的浓度而不是 PCs 的浓度与细分果实组织中的镉浓度相关，这表明镉以 Cd-GSH 形式的韧皮部特异性转运机制。根据综合数据，提出了一种描述长距离韧皮部运输与库器官中镉分布之间关系的暂定模型。讨论了对食品安全的影响。