The urea transporter DUR3 contributes to rice production under nitrogen‐deficient and field conditions

Abstract

Nitrogen is one of the most important elements for plant growth, and urea is one of the most frequently used nitrogen fertilizers worldwide. Besides the exogenously-supplied urea to the soil, urea is endogenously synthesized during secondary nitrogen metabolism. Here, we investigated the contribution of a urea transporter, DUR3, to rice production using a reverse genetic approach combined with localization studies. Tos17 insertion lines for DUR3 showed a 50% yield reduction in hydroponic culture, and a 26.2% yield reduction in a paddy field, because of decreased grain filling. Because shoot biomass production and shoot total N was not reduced, insertion lines were disordered not only in nitrogen acquisition but also in nitrogen allocation. During seed development, DUR3 insertion lines accumulated nitrogen in leaves and could not sufficiently develop their panicles, although shoot and root dry weights were not significantly different from the wild-type. The urea concentration in old leaf harvested from DUR3 insertion lines was lower than that in wild-type. DUR3 promoter-dependent -glucuronidase (GUS) activity was localized in vascular tissue and the midribs of old leaves. These results indicate that DUR3 contributes to nitrogen translocation and rice yield under nitrogen-deficient and field conditions.

Comparative Transcriptomics of Rice Genotypes with Contrasting Responses to Nitrogen Stress Reveals Genes Influencing Nitrogen Uptake through the Regulation of Root Architecture

“…Another gene, OsDUR3 (LOC_Os10g42960), a high-affinity urea transporter, was upregulated under low N, confirming earlier studies [21,46]. Since OsDUR3 improved the rice yield under nitrogen deficient conditions by increasing urea uptake [47], the increased expressions of OsDUR3 should help in N foraging. Therefore, the upregulation of both OsDUR3 and OsNRT2.1 may be enhancing N foraging in the form of either nitrate or urea.…”

Effect of Foliar Application of Various Nitrogen Forms on Starch Accumulation and Grain Filling of Wheat (Triticum aestivum L.) Under Drought Stress

“…As the core structural element of proteins, including enzymes and those involved in photosynthetic systems, nitrogen (N) is a key factor in crop growth and productivity (Beier et al, 2018;Evans and Clarke, 2018). N and water interact in significant ways that affect wheat growth.…”

The function of high‐affinity urea transporters in nitrogen‐deficient conditions

“…The translocation happens over two pathways, first is the direct long‐distance transport of urea, and second is the transport of amino acids, which were assimilated by the GS/GOGAT cycle after the hydrolysis of urea to ammonium, as shown on the plant level for Arabidopsis and rice in Figure 1A,B. The mechanism of N translocation should be the same in Arabidopsis and rice, though experimental evidence for both plants is not complete; In Arabidopsis, a urea leach from the petiole was observed (Figure 1A; Bohner et al, 2015), and in rice the N translocation was shown by 15 N (Figure 1B, Beier et al, 2019). The pathway of urea degradation in the tissue itself in rice is again supported by the co‐localization of major pathway enzymes like urease, arginase, and GS/GOGAT isoforms in senescing tissues (Yabuki et al, 2017; Yamaya & Kusano, 2014).…”

“…A broader picture of the DUR3 involvement can be seen when its localization is taken into account. In Arabidopsis and Oryza sativa (rice), the localization of DUR3 in senescing leaves was primarily in the vascular system, and the involvement in nitrogen translocation was experimentally confirmed in both species (Beier et al, 2019; Bohner et al, 2015). The translocation happens over two pathways, first is the direct long‐distance transport of urea, and second is the transport of amino acids, which were assimilated by the GS/GOGAT cycle after the hydrolysis of urea to ammonium, as shown on the plant level for Arabidopsis and rice in Figure 1A,B.…”

“…The direct consequences of DUR3 function for agronomic traits (e.g. yield) were subsequently analyzed in rice plants under field and nitrogen‐limited conditions (Beier et al, 2019). In short, the DUR3 deficient rice led to a decreased yield due to limited grain filling, which is caused by a decreased N partitioning to panicles.…”