Genome-Wide Identification of AMT2-Type Ammonium Transporters Reveal That CsAMT2.2 and CsAMT2.3 Potentially Regulate NH4+ Absorption among Three Different Cultivars of Camellia sinensis

Abstract

Ammonium (NH4+), as a major inorganic source of nitrogen (N) for tea plant growth, is transported and distributed across membranes by the proteins of ammonium transporters (AMTs). However, the AMT2-type AMTs from tea plants remain poorly understood. In this study, five CsAMT2 subfamily genes were identified in tea plant genomes, and their full-length coding sequences (CDS) were isolated from roots. Then, a NH4+ uptake kinetic comparison of Fudingdabaicha (FD), Huangdan (HD), and Maoxie (MX) showed that FD was a high N efficiency (HNE) cultivar that had a wide range of adaptability to NH4+, HD was a high N efficiency under high N conditions (HNEH) cultivar, in which it was easy to obtain higher yield in a high N environment, and MX was a high N efficiency under low N conditions (HNEL) cultivar, which had a higher affinity for NH4+ than the other two. Tissue-specific expression analysis suggested that CsAMT2.2 and CsAMT2.3 were highly expressed in the roots, indicating that these two members may be unique in the CsAMT2 subfamily. This is further supported by our findings from the temporal expression profiles in the roots among these three different N adaptation cultivars. Expression levels of CsAMT2.2 and CsAMT2.3 in FD and HD were upregulated by a short time (2 h) under high NH4+ treatment, while under low NH4+ treatment, CsAMT2.2 and CsAMT2.3 were highly expressed at 0 h and 2 h in the HNEL-type cultivar—MX. Furthermore, the functional analysis illustrated that CsAMT2.2 and CsAMT2.3 could make a functional complementation of NH4+-defective mutant yeast cells at low NH4+ levels, and the transport efficiency of CsAMT2.3 was higher than that of CsAMT2.2. Thus, we concluded that CsAMT2.2 and CsAMT2.3 might play roles in controlling the NH4+ uptake from the soil to the roots. These results will further the understanding of the NH4+ signal networks of AMT2-type proteins in tea plants.

Overexpression of Nta-miR6155 confers resistance to Phytophthora nicotianae and regulates growth in tobacco (Nicotiana tabacum L.)

“…Interestingly, we found that AMT2, encoding a high-affinity ammonium transporter, is a potential target gene of miR6155. In previous studies, it has been shown that AMT2 potentially regulates ammonium uptake in different plants (Zhang et al, 2022). Additionally, Giehl et al has shown that AMT2;1 was crucial for root-to-shoot translocation of ammonium in Arabidopsis (Giehl et al, 2017).…”

Genome-wide identification, expression profiling, and protein interaction analysis of the CCoAOMT gene family in the tea plant (Camellia sinensis)

“…Specific primers (Supplementary Table 3 ) for the CCoAOMT genes were designed by Primer Premier 5.0 software. The CsGAPDH1 (KA295375.1)was selected as the internal reference gene for the detection of gene expression [ 52 ]. Each 10 µL reaction contained 5 µL of 2×PerfectStart Green qPCR SuperMix, 0.5 µL of forward primer, 0.5 µL of reverse primer, 1 µL of cDNA, and 3 µL of RNase-free water.…”

Nitrogen transport and assimilation in tea plant (Camellia sinensis): a review

“…Their results suggested that the differences in these indicators varied in the five cultivars tested as the N concentration increased and membership function could be used to evaluated the NUE of each cultivar synthetically. Also, CsAMTs expression profiles in response to NH 4 + differed among cultivars ( Zhang et al., 2018 ; Zhang et al., 2022b ). Still, it was possible to detect that CsNRT2 participated in NO 3 − transport under low N conditions ( Hu et al., 2023 ; Lin et al., 2023b ).…”

“…CsAMT1.1 and CsAMT1.5 expression levels were significantly higher in the roots of the FuDingDaBaiCha cultivar than Longjin43 cultivar ( Zhang et al., 2022a ). After NH 4 + resupply, CsAMT1.2 , CsAMT2.2 , and CsAMT2.3 genes were differentially induced in tea cultivars with different NH 4 + -uptake efficiency, indicating the uneven NH 4 + transport capacity among cultivars ( Zhang et al., 2018 ; Zhang et al., 2022b ).…”

“…Because tea roots show a preference for NH 4 + uptake as the nitrogen source, the kinetic parameters of this cation are usually used to define tea adaptability to N availability. According to current studies on NH 4 + dynamics, tea cultivars may be classified into three categories: (1) cultivars with high K m and high V max can produce high yields in soils with elevated N contents; TeiGuanYin, HuangDan, and Yubukita cultivars belong to this type; (2) cultivars with low K m and low V max may display a good performance in soils with low N concentrations; YingShuang and MaoXie belong to this type; (3) cultivars with high K m and low V max are the most flexible concerning N levels, being appropriate for both high and low N conditions; ZhongCha#302 and FuDingDaBaiCha belong to this type (Wang et al, 2005;Liu, 2016;Zhang et al, 2018;Zhang et al, 2022b). Notably, N flux was calculated as the N content in the roots based on 15 N labeling in most studies, and there are still many cultivars falling into different groups in different studies due to different number of tested cultivars and methodological approaches.…”