Transporters for ammonium, amino acids and peptides are expressed in pitchers of the carnivorous plant Nepenthes.
Transporters for ammonium, amino acids and peptides are expressed in pitchers of the carnivorous plant Nepenthes.
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DOI：
10.1046/j.1365-313x.1999.00414.x
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发表时间：
1999-03
期刊：
影响因子：
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通讯作者：
Waltraud X. Schulze;Wolf B. Frommer;John M. Ward
中科院分区：
文献类型：
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作者：
Waltraud X. Schulze;Wolf B. Frommer;John M. Ward
昆虫的捕获和消化对肉食性植物的氮素收支有很大贡献。在猪笼草中，昆虫来源的含氮化合物从猪笼液中进口，并通过维管组织运输到整个植物，以支持生长。营养物质的进口和分配可能需要跨膜氮转运蛋白。在猪笼草中发现了编码含氮化合物氨、氨基酸和多肽转运蛋白的三类基因的代表。在细胞水平上研究了一个氨基转运蛋白基因、三个氨基酸转运蛋白基因和一个多肽转运蛋白基因在猪笼草昆虫诱捕器官中的表达。在水壶下部消化腺的头部细胞中检测到了铵转运蛋白基因NaAMT1的表达，NaAMT1可能在水壶液氨的吸收中起作用。氨基酸转运蛋白基因NaAAP1在维管组织周围的束鞘细胞中表达。为了了解猪笼体内可能需要跨膜运输的位置，用荧光染料检测了共质体和质外体的连续性。皮质细胞与维管束之间未见胞质连接。因此，NaAAP1编码的氨基酸转运体可能参与氨基酸向维管组织的转运。相反，在猪笼草维管组织的韧皮部细胞中检测到了多肽转运蛋白基因NaNTR1的表达。NaNTR1可能通过将多肽装载到韧皮部而在水壶输出氮的过程中发挥作用。
Insect capture and digestion contribute substantially to the nitrogen budget of carnivorous plants. In Nepenthes, insect-derived nitrogenous compounds are imported from the pitcher fluid and transported throughout the plant via the vascular tissue to support growth. Import and distribution of nutrients may require transmembrane nitrogen transporters. Representatives of three classes of genes encoding transporters for the nitrogenous compounds ammonium, amino acids and peptides were identified in Nepenthes pitchers. The expression at the cellular level of an ammonium transporter gene, three amino acid transporter genes, and one peptide transporter gene were investigated in the insect trapping organs of Nepenthes. Expression of the ammonium transporter gene NaAMT1 was detected in the head cells of digestive glands in the lower part of the pitcher where NaAMT1 may function in ammonium uptake from the pitcher fluid. One amino acid transporter gene, NaAAP1, was expressed in bundle sheath cells surrounding the vascular tissue. To understand the locations where transmembrane transport could be required within the pitcher, symplasmic and apoplasmic continuity was probed using fluorescent dyes. Symplasmic connections were not found between cortical cells and vascular bundles. Therefore, the amino acid transporter encoded by NaAAP1 may be involved in transport of amino acids into the vascular tissue. In contrast, expression of the peptide transporter gene NaNTR1 was detected in phloem cells of the vascular tissue within pitchers. NaNTR1 may function in the export of nitrogen from the pitcher by loading peptides into the phloem.