Li Xia, Long Xiahou, Hongling Liu, Xinwan Zhang, Elizabeth Pilon-Smits, Marinus Pilon, Wei Huang, Pu Wang, Mingle Wang, Fei Guo, Yu Wang, Hua Zhao, Dejiang Ni
{"title":"Involvement of Camellia sinensis AAP3.1 in nitrogen allocation is validated in tea plants and Arabidopsis","authors":"Li Xia, Long Xiahou, Hongling Liu, Xinwan Zhang, Elizabeth Pilon-Smits, Marinus Pilon, Wei Huang, Pu Wang, Mingle Wang, Fei Guo, Yu Wang, Hua Zhao, Dejiang Ni","doi":"10.1016/j.hpj.2025.09.015","DOIUrl":"https://doi.org/10.1016/j.hpj.2025.09.015","url":null,"abstract":"Amino acids are the primary assimilated form of nitrogen (N) in plants, and their transport and distribution between source and sink organs determine the yield and quality of tea plants (<ce:italic>Camellia sinensis</ce:italic> L.). Amino acid permeases (AAPs) play critical roles in amino acid uptake, transport, and distribution, yet the specific functions of most <ce:italic>CsAAPs</ce:italic> remain largely unelucidated. Here, we aimed to identify the functional role of <ce:italic>CsAAP3.1</ce:italic>, in amino acid transport and N allocation dynamics. Based on bioinformatics analysis and the expression pattern profiling, we identified <ce:italic>CsAAP3.1</ce:italic> as a candidate gene. Its expression patterns across tissues and N conditions were characterized and its function using heterologous overexpression in <ce:italic>Arabidopsis</ce:italic> and virus-induced gene silencing (VIGS) in tea plants. <ce:italic>CsAAP3.1</ce:italic> showed distinct transcript levels in leaves, veins, and roots. Under low nitrogen (LN, 0.25 mmol · L<ce:sup loc=\"post\">-1</ce:sup> N) conditions, its expression was repressed in roots but induced in shoots. Functional assays revealed that <ce:italic>CsAAP3.1</ce:italic> is a broad-specificity amino acid transporter, capable of transporting theanine (Thea) and twelve other amino acids. Compared to wild-type (WT), <ce:italic>CsAAP3.1</ce:italic> overexpressing <ce:italic>Arabidopsis</ce:italic> lines exhibited lower amino acid levels and enhanced N accumulation under low-N conditions, and higher amino acid levels with reduced N allocation in young leaves under normal nitrogen (NN, 5 mmol · L<ce:sup loc=\"post\">-1</ce:sup> N) conditions at maturity. Moreover, in tea plants, VIGS-mediated silencing of <ce:italic>CsAAP3.1</ce:italic> reduced free amino acids and N in young leaves, with <ce:sup loc=\"pre\">15</ce:sup>N tracing showing inhibited amino acid transport from mature to young leaves and downregulated key nitrogen assimilation genes in young leaves, indicating <ce:italic>CsAAP3.1</ce:italic> mediated source-to-sink amino acid transport and regulates nitrogen accumulation in young leaves. Taken together, these findings suggest that <ce:italic>CsAAP3.1</ce:italic> optimizes N allocation and partitioning to acclimate to low-N, which may have applications for tea quality improvement by upregulating amino acid level.","PeriodicalId":13178,"journal":{"name":"Horticultural Plant Journal","volume":"127 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2026-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}