Genome-Wide Identification and Expression Analysis of AMT and NRT Gene Family in Pecan (Carya illinoinensis) Seedlings Revealed a Preference for NH4+-N

Abstract

Nitrogen (N) is a major limiting factor for plant growth and crop production. The use of N fertilizer in forestry production is increasing each year, but the loss is substantial. Mastering the regulatory mechanisms of N uptake and transport is a key way to improve plant nitrogen use efficiency (NUE). However, this has rarely been studied in pecans. In this study, 10 AMT and 69 NRT gene family members were identified and systematically analyzed from the whole pecan genome using a bioinformatics approach, and the expression patterns of AMT and NRT genes and the uptake characteristics of NH4+ and NO3− in pecan were analyzed by aeroponic cultivation at varying NH4+/NO3− ratios (0/0, 0/100,25/75, 50/50, 75/25,100/0 as CK, T1, T2, T3, T4, and T5). The results showed that gene duplication was the main reason for the amplification of the AMT and NRT gene families in pecan, both of which experienced purifying selection. Based on qRT-PCR results, CiAMTs were primarily expressed in roots, and CiNRTs were majorly expressed in leaves, which were consistent with the distribution of pecan NH4+ and NO3− concentrations in the organs. The expression levels of CiAMTs and CiNRTs were mainly significantly upregulated under N deficiency and T4 treatment. Meanwhile, T4 treatment significantly increased the NH4+, NO3−, and NO2− concentrations as well as the Vmax and Km values of NH4+ and NO3− in pecans, and Vmax/Km indicated that pecan seedlings preferred to absorb NH4+. In summary, considering the single N source of T5, we suggested that the NH4+/NO3− ratio of 75:25 was more beneficial to improve the NUE of pecan, thus increasing pecan yield, which provides a theoretical basis for promoting the scale development of pecan and provides a basis for further identification of the functions of AMT and NRT genes in the N uptake and transport process of pecan.

Functional Identification and Genetic Transformation of the Ammonium Transporter PtrAMT1;6 in Populus

“…After the transformation of Agrobacterium tumefaciens GV3101-pCAMBIA 1301-PtrAMT1;6P into the Arabidopsis Col-0 ecotype, pure lines were screened and used for GUS staining. The results showed that, at the seedling stage, GUS was expressed mainly on the rootstock junction, cotyledon petioles, and the veins and mesophyll cells closely connected to the petioles, but not in the roots or the newly emerged leaves, whereas the AMT gene was expressed mainly in the roots of Carya illinoinensis, probably because PtrAMT1;6 is a gene that controls the ammonium recycling function in the aboveground parts [25]. Although Arabidopsis and poplar are far apart in morphological structure, the expression activity of the PtrAMT1;6 promoter in Arabidopsis is not fully indicative of its expression activity in P. trichocarpa, but this result suggests that the PtrAMT1;6 promoter has promoter activity.…”

Genome-Wide Analysis of Sweet Potato Ammonium Transporter (AMT): Influence on Nitrogen Utilization, Storage Root Development and Yield

“…We performed a genome-wide analysis to identify 12 AMT family genes that belong to two subfamilies in sweet potato. The phylogenetic analyses of the AMT proteins among sweet potato, Arabidopsis, rice, tomato, cassava, soybean, and maize AMT proteins indicated that the AMT of the studied species can be divided into three groups according to homology [48]. Furthermore, IbAMT1.3, AtAMT1.1, and SlAMT1.1 are homologous, and IbAMT1.5 shows a close relationship with AtAMT1.2 and SlAMT1.2.…”

Nitrogen Journey in Plants: From Uptake to Metabolism, Stress Response, and Microbe Interaction

“…NRT1, NRT2, and NRT3 have different structural conformations (Figure 1). As a result, the Pfam database collects these genes under distinct families: PF00854 for NRT1, PF07690 for NRT2, and PF16974 for NRT3 [64]. PF00854 refers to the proton-dependent oligopeptide transporter (POT) family (also known as the peptide transporter (PTR) family) and is a class of energy-dependent transporters discovered in organisms ranging from bacteria to humans [65].…”