Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China.
Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China; Key Laboratory of Biology, Genetics and Breeding of Special Economic Animals and Plants, Ministry of Agriculture and Rural Affairs, Hangzhou 310008, China.
Sci Total Environ. 2024 Nov 10;950:175088. doi: 10.1016/j.scitotenv.2024.175088. Epub 2024 Jul 27.
Residual pesticides in agricultural environments, including soil and irrigation water, can be taken up by plants, and thus pose a potential risk to food safety. Although tolfenpyrad has been widely used in tea plantations, limited information is available on its root uptake and fate in tea plants (Camellia sinensis L.). Exploring the mechanisms involved is crucial for understanding the migration and accumulation of tolfenpyrad in tea plants, particularly in the edible parts. In this study, root uptake of tolfenpyrad and its subsequent translocation, distribution, and metabolism in tea seedlings were investigated. The results indicated that the passive transport and apoplastic pathway dominated the root uptake of tolfenpyrad. After uptake, tolfenpyrad distributed predominantly in the cell walls (90.8-92.0 %) of roots, resulting in limited upward translocation in water-soluble fractions through transpirational pull, with translocation factor values far <1 (TF = 0.115-0.453 and TF = 0.039-0.184). Similar accumulation patterns were observed for the carboxylated metabolite PT-CA as well as hydroxylated metabolite PT-OH. Interestingly, the subcellular distribution of PT-CA in stems was much different from that of the parent tolfenpyrad: PT-CA mainly distributed in the stem cell walls (41.72 %) and cell organelles (56.18 %) at 3 h, then gradually transferred into the cell-soluble fractions (33.07 %) after 120 h. Results from the present study indicated limited upward translocation of tolfenpyrad with its main metabolites to leaves. This finding helps to alleviate concerns about environmental residual tolfenpyrad in tea consumption and provides valuable information for the safety evaluation of tolfenpyrad.
农业环境（包括土壤和灌溉水）中的残留农药可能被植物吸收，从而对食品安全构成潜在威胁。尽管噻虫啉已被广泛用于茶园，但关于其在茶树（Camellia sinensis L.）中的根系吸收和归宿的信息有限。探索其中涉及的机制对于了解噻虫啉在茶树中的迁移和积累至关重要，特别是在可食用部分。本研究调查了噻虫啉在茶树苗根系中的吸收及其随后的迁移、分布和代谢。结果表明，被动运输和质外体途径主导了噻虫啉的根系吸收。吸收后，噻虫啉主要分布在根部细胞壁（90.8-92.0%）中，通过蒸腾拉力，在水溶性部分中向上迁移的量有限，迁移因子值远小于 1（TF=0.115-0.453 和 TF=0.039-0.184）。羧酸代谢物 PT-CA 和羟基代谢物 PT-OH 的积累模式也相似。有趣的是，PT-CA 在茎中的亚细胞分布与母体噻虫啉有很大不同：PT-CA 在 3 小时时主要分布在茎细胞壁（41.72%）和细胞器官（56.18%）中，然后在 120 小时后逐渐转移到细胞可溶性部分（33.07%）。本研究结果表明，噻虫啉及其主要代谢物向上迁移到叶片的量有限。这一发现有助于减轻对茶消费中环境残留噻虫啉的担忧，并为噻虫啉的安全评估提供有价值的信息。
