Hexafluoropropylene oxide (HFPO) homologues, which are important alternatives to perfluorooctanoic acid, have been frequently identified in crops. Although exposure to HFPO homologues via crops may pose non-negligible threats to humans, their impact on crops is still unknown. In this study, the accumulation, transport, and distribution mechanisms of three HFPO homologues in lettuce were investigated at the plant, tissue, and cell levels. More specifically, HFPO trimer acid and HFPO tetramer acid were primarily fixed in roots and hardly transported to shoots (TF, 0.06–0.63). Conversely, HFPO dimer acid (HFPO-DA) tended to accumulate in lettuce shoots 2–264 times more than the other two homologues, thus resulting in higher estimated daily intake values. Furthermore, the dissolved organic matter derived from root exudate enhanced HFPO-DA uptake by increasing its desorption fractions in the rhizosphere. The transmembrane uptake of HFPO homologues was controlled by means of a transporter-mediated active process involving anion channels, with the uptake of HFPO-DA being additionally facilitated by aquaporins. The higher accumulation of HFPO-DA in shoots was attributed to the larger proportions of HFPO-DA in the soluble fraction (55–74%) and its higher abundance in both vascular tissues and xylem sap. Our findings expand the understanding of the fate of HFPO homologues in soil–crop systems and reveal the underlying mechanisms of the potential exposure risk to HFPO-DA.

中文翻译：

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对六氟环氧丙烷同系物（全氟辛酸的重要替代品）在生菜 (Lactuca sativa L.) 中的积累、运输和分布机制的新见解

六氟环氧丙烷 (HFPO) 同系物是全氟辛酸的重要替代品，在农作物中经常被发现。尽管通过农作物接触HFPO同系物可能对人类造成不可忽视的威胁，但它们对农作物的影响仍然未知。本研究在植物、组织和细胞水平上研究了生菜中三种 HFPO 同系物的积累、运输和分布机制。更具体地说，HFPO 三聚酸和 HFPO 四聚酸主要固定在根中，几乎不运输到芽中（TF，0.06-0.63）。相反，HFPO 二聚酸 (HFPO-DA) 在生菜芽中的积累量往往是其他两种同系物的 2-264 倍，因此导致每日估计摄入量较高。此外，来自根系分泌物的溶解有机物通过增加其在根际的解吸分数来增强HFPO-DA的吸收。HFPO 同系物的跨膜摄取是通过涉及阴离子通道的转运蛋白介导的活性过程来控制的，水通道蛋白还进一步促进了 HFPO-DA 的摄取。芽中 HFPO-DA 的较高积累归因于可溶性部分中 HFPO-DA 的比例较大（55-74%）及其在维管组织和木质部汁液中的丰度较高。我们的研究结果扩大了对 HFPO 同系物在土壤-作物系统中命运的理解，并揭示了 HFPO-DA 潜在暴露风险的潜在机制。