Co-Overexpression of OsNAR2.1 and OsNRT2.3a Increased Agronomic Nitrogen Use Efficiency in Transgenic Rice Plants.

Jingguang Chen,Jingguang Chen,Jingguang Chen,Xiaoqin Liu,Xiaoqin Liu,Shuhua Liu,Limei Zhao,Xiaoru Fan,Xiaorong Fan,Guohua Xu,Miaoquan Song

doi:10.3389/fpls.2020.01245

Jingguang Chen, Jingguang Chen + Show 9 more

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https://doi.org/10.3389/fpls.2020.01245

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The NO3 - transporter plays an important role in rice nitrogen acquisition and nitrogen-use efficiency. Our previous studies have shown that the high affinity systems for nitrate uptake in rice is mediated by a two-component NRT2/NAR2 transport system. In this study, transgenic plants were successful developed by overexpression of OsNAR2.1 alone, OsNRT2.3a alone and co-overexpression of OsNAR2.1 and OsNRT2.3a. Our field experiments indicated that transgenic lines expressing p35S:OsNAR2.1 or p35S:OsNAR2.1-p35S:OsNRT2.3a constructs exhibited increased grain yields of approximately 14.1% and 24.6% compared with wild-type (cv. Wuyunjing 7, WT) plants, and the agricultural nitrogen use efficiency increased by 15.8% and 28.6%, respectively. Compared with WT, the 15N influx in roots of p35S:OsNAR2.1 and p35S: OsNAR2.1-p35S:OsNRT2.3a lines increased 18.9%‑27.8% in response to 0.2 mM, 2.5 mM 15NO3 –, and 1.25 mM 15NH4 15NO3, while there was no significant difference between p35S:OsNAR2.1 and p35S:OsNAR2.1-p35S:OsNRT2.3a lines; only the 15N distribution ratio of shoot to root for p35S:OsNAR2.1-p35S:OsNRT2.3a lines increased significantly. However, there were no significant differences in nitrogen use efficiency, 15N influx in roots and the yield between the p35S:NRT2.3a transgenic lines and WT. This study indicated that co-overexpression of OsNAR2.1 and OsNRT2.3a could increase rice yield and nitrogen use efficiency.

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Nitrogen (N) is an essential macronutrient for plant growth and crop productivity, it affects all levels of plant function from metabolism to resource allocation, growth, and development (Crawford, 1995; Scheible et al, 2004)
Co-Overexpression of OsNAR2.1 and OsNRT2.3a nitrification is inhibited, NH4+ is the main inorganic nitrogen in rhizosphere soil, rice is generally considered as ammonium-preferring plant (Arth et al, 1998; Kronzucker et al, 1999)
We focus on co-overexpressed OsNAR2.1 and OsNRT2.3a in rice, overexpression of OsNAR2.1 or OsNRT2.3a alone as control and explored the effect of cooverexpression of OsNAR2.1 and OsNRT2.3a on NO3– uptake, yield and nitrogen use efficiency uptake by rice

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Nitrogen (N) is an essential macronutrient for plant growth and crop productivity, it affects all levels of plant function from metabolism to resource allocation, growth, and development (Crawford, 1995; Scheible et al, 2004). Nitrate nitrogen (NO3–) and ammonium nitrogen (NH4+) are two main inorganic nitrogen sources in plant growth. Co-Overexpression of OsNAR2.1 and OsNRT2.3a nitrification is inhibited, NH4+ is the main inorganic nitrogen in rhizosphere soil, rice is generally considered as ammonium-preferring plant (Arth et al, 1998; Kronzucker et al, 1999). For its well-developed aerial tissue, rice can transport and secrete oxygen from photosynthesis above ground to the rhizosphere (Aurelio et al, 2003). During the late stage of rice growth and development, when it has been going through the process of long-term alternate wetting and drying irrigation or the whole growth stage of upland rice, the uptake of NO3– was higher than that of NH4+ by rice (Arth et al, 1998; Wang et al, 2004)

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