Comprehensive analysis of the LHT gene family in tobacco and functional characterization of NtLHT22 involvement in amino acids homeostasis

Abstract

Amino acids are vital nitrogen (N) sources for plant growth, development, and yield. The uptake and translocation of amino acids are mediated by amino acid transporters (AATs). The AATs family including lysine-histidine transporters (LHTs), amino acid permeases (AAPs), and proline transporters (ProTs) subfamilies have been identified in various plants. However, little is known about these genes in tobacco. In this study, we identified 23 LHT genes, the important members of AATs, in the tobacco genome. The gene structure, phylogenetic tree, transmembrane helices, chromosomal distribution, cis-regulatory elements, and expression profiles of NtLHT genes were systematically analyzed. Phylogenetic analysis divided the 23 NtLHT genes into two conserved subgroups. Expression profiles confirmed that the NtLHT genes were differentially expressed in various tissues, indicating their potential roles in tobacco growth and development. Cis-elements analysis of promoters and expression patterns after stress treatments suggested that NtLHT genes probable participate in abiotic stress responses of tobacco. In addition, Knock out and overexpression of NtLHT22 changed the amino acids homeostasis in the transgenic plants, the contents of amino acids were significantly decreased in NtLHT22 overexpression plants than wild-type. The results from this study provide important information for further studies on the molecular functions of the NtLHT genes.

Amino Acid Transporter as a Potential Carrier Protein for the Root-to-Shoot Translocation of Polybrominated Diphenyl Ethers in Rice

“…Current research suggested that exogenous pollutants often hitchhike on nutrient/ATP transport proteins to facilitate their long-distance translocation and accumulation in vivo . For example, PBDEs have been found to bind to serum albumin which transports fatty acids, or thyroid hormone transporter proteins in animals and humans, enabling their transport and distribution across different tissues. , In plants, ATP-binding cassette-type (ABC) transporters are involved in transporting phytochelatin–Cd complexes from roots to shoots, thereby increasing Cd bioavailability and exacerbating physiological damage. , Some amino acid transporters (AATs) have been reported to be promising targets in cancer and tumor therapy via conjunction with some amino acid analogues such as gabapentin and baclofen. , The lysine histidine transporter (LHT), a typical AAT, has also been shown to be effective in transporting 1-aminocyclopropane-1-carboxylic acid, a biosynthetic precursor of ethylene in plants. − These studies suggested the potential ability of AATs in transporting substances other than amino acids. Thus, we hypothesized that PBDEs, which possess phenyl groups similar to those of aromatic amino acids ( e.g.…”