Improving nitrogen use efficiency by manipulating nitrate remobilization in plants

Targeting Nitrogen Metabolism and Transport Processes to Improve Plant Nitrogen Use Efficiency

“…While it remains to be determined if rootspecific overexpression of NRTs may be sufficient for enhancing N uptake, research suggests that downstream nitrate transport processes may additionally or dominantly contribute to the observed increases in NUE. Indeed, recent work in Arabidopsis (Arabidopsis thaliana), tobacco (Nicotiana tabacum), and rice (Oryza sativa) showed that overexpression of the hyperactive chimeric nitrate transporter AtNC4N in the phloem of old leaves results in improved NUE under high and low N status (Chen et al, 2020). This study also supports the fact that during leaf senescence, besides amino acids and peptides (Winter et al, 1992;Feller and Fischer, 1994;Masclaux et al, 2000), nitrate recycling from the vacuole and subsequent source-tosink partitioning contribute to sink N supply.…”

“…nitrate transporter either throughout rice plants, or in the epidermis and vascular tissues of roots and parenchyma cells of culms and leaf sheaths resulted in increased grain yield and NUE under high and low N supply, due to improved N utilization for grain development (Wang et al, 2018b). As nitrate transport, related N assimilation, and amino acid partitioning processes are highly intertwined (Tegeder and Rentsch, 2010;Tegeder, 2012Tegeder, , 2014Tegeder and Masclaux-Daubresse, 2018), it would be interesting to examine if in AtNC4N and OsNRT1.1A overexpressors co-regulated by changes in amino acid pools and transport also add to the observed increases in seed yield, seed N content, and NUE (Wang et al, 2018b;Chen et al, 2020).…”

“…Positive results were achieved for genes of a nitrate reductase (OsNR2, Gao et al, 2019b), glutamine synthetases (NtGS1, Oliveira et al, 2002;ZmGln1-3, Martin et al, 2006;SbGS1, Urriola and Rathore, 2015;bacterial GS I, Zhu et al, 2015;DvGS2, Zhu et al, 2014), glutamate synthases (MsNADH-GOGAT, Chichkova et al, 2001;OsGOGAT1, Lee et al, 2020a), asparagine synthetases (OsASN1, Lee et al, 2020b;E. coli EcasnA, Seiffert et al, 2004), nitrate (OsNRT1.1A, Wang et al, 2018b; (At)NC4N, a synthetic gene construct based on Arabidopsis gene sequences, Chen et al, 2020), and amino acid transporters (PsAAP1, Perchlik and Tegeder, 2017) as well as for glutamate dehydrogenases (Trichurus sp. TrGDH, Du et al, 2019;C.…”

“…While amino acids, peptides, or even proteins may be taken up from the soil (Chapin et al, 1993;Näsholm et al, 2009;Tegeder and Rentsch, 2010), nitrate and ammonium are often preferred (Crawford and Glass, 1998;Loqué and von Wirén, 2004;Krapp et al, 2014). However, the inorganic N is only usable by plants when it is assimilated into amino acids, a process that primarily occurs in source organs such as the roots or leaves (Andrews et al, 1992;Lam et al, 1996;Miller et al, 2007;Xu et al, 2012;Krapp, 2015) but can also take place in sinks like seeds (Rochat and Boutin, 1992;Weber et al, 1998;Chen et al, 2020).…”

“…Numerous genes related to these developmental and physiological processes have been identified and their importance for plant growth, function, and seed yield has been demonstrated. We would like to refer the readers to some recent reviews that provide comprehensive overviews on the discoveries (Miller et al, 2007(Miller et al, , 2008Xu et al, 2012;Han et al, 2015;Mandal et al, 2018;Tegeder and Masclaux-Daubresse, 2018;Wang et al, 2018a;Raghuram and Sharma, 2019;Chen et al, 2020;Fernie et al, 2020;Fichtner et al, 2020;Li et al, 2020;Vidal et al, 2020). The current work will focus on new findings in N metabolism and transport, along with their associated genes and proteins, and analyze their role in improving NUE under high and low N conditions.…”