Genome-Wide Identification and Expression Analysis of Gs and Gogat Gene Family in Pecan (<em>Carya illinoinensis</em>) under Different Nitrogen Forms

Abstract

Nitrogen (N) is an important mineral nutrient for plant growth, as well as a limiting factor for crop yield, and how to improve the utilization efficiency of N fertilizer by plants is currently a research hotspot. This article uses bioinformatics methods to identify and analyze members of the glutamine synthetase (GS) and glutamate synthase (GOGAT) gene families in pecan. A total of 6 GS genes and 4 GOGAT genes were identified, and their physicochemical properties, gene structures, and homologous evolutionary relationships were analyzed. Analysis of tissue-specific expression of GS and GOGAT genes based on transcriptome data from pecan. The enzyme activities of GS and GOGAT and the gene expression were quantitatively analyzed under different N form ratios in pecan. According to the results, the promoter cis-acting elements of GS and GOGAT genes can be roughly divided into three types: light-responsive elements, hormone-responsive elements, and stress-responsive elements. The results of homologous evolution showed that there was no tandem duplication event for the two gene families, and GS and GOGAT have undergone purification during the evolutionary process. CiGS2s and CiFd-GOGATs were expressed mainly in leaves, and CiNADH-GOGATs were expressed mainly in fruits. The qPCR analysis results showed that T4 treatment significantly increased the expression levels of CiGS and CiGOGAT genes in the leaves. The enzyme activities of GS and GOGAT in pecan were significantly increased under T3, T4, and T5 treatments. In summary, a higher proportion of ammonium nitrogen (NH4+) in the nutrient solution was profit to pecan NH4+ assimilation. This study determined the appropriate nitrogen ratio for pecan, promoting a theoretical basis for reducing environmental pollution caused by nitrogen fertilizer and improving the nitrogen utilization efficiency of pecan. In summary, both CiGSs and CiGOGATs exhibit tissue specificity, and an ammonium-nitrate mixture with a higher proportion of NH4+ is more favorable for NH4+ assimilation in pecan. This study provides a reference basis for further understanding the functions of CiGSs and CiGOGATs in pecan, and offers a theoretical foundation for improving N use efficiency in pecan.

Genomic organization and expression profiles of nitrogen assimilation genes in Glycine max

“…This implies a role for the soybean NAGs in modulating hormone response and stress tolerance. Our observations align with previous research on rice and pecan ( Qiao et al, 2023 ; Rohilla & Yadav, 2023 ).…”

“…A comparative phylogenetic analysis revealed a high degree of conservation in NAGs across various legume species including G. max , emphasizing the close relationship among nitrogen assimilation genes in diverse crops. The classification of NAGs was consistent with gene structures, motif distributions, and existing literature ( Li et al, 2022 ; Qiao et al, 2023 ).…”

“…Specifically, under high nitrate (HN) treatment conditions, all selected NAGs showed up-regulated expression patterns, aligning with the results of Balotf, Kavoosi & Kholdebarin (2016) , who observed up regulation of wheat NAG expression in response to high nitrate (50 mM KNO 3 ) treatment. Similarly, Qiao et al (2023) reported significant up regulation of pecan GS genes under high nitrate concentrations. These studies collectively suggest that these genes may play a vital role in the response of plants to high nitrate levels, potentially through their involvement in the assimilation and metabolism of nitrogen compounds.…”

“…The GS , GOGAT , and NR gene families have been studied in other plant species, like rice, pecan, and rapeseed ( He et al, 2021 ; Li et al, 2022 ; Qiao et al, 2023 ), a comprehensive genome-wide analysis of these gene families in soybean is still lacking. This study aims to fill this gap by identifying and analyzing these gene families in six legume species: Glycine max , Cicer arietinum , Lotus japonicus , Phaseolus lunatus , Phaseolus vulgaris , and Vigna unguiculata , with chromosome numbers of 20, 8, 6, 11, 11, and 11, respectively.…”