Functional linkage between N acquisition strategies and aeration capacities of hydrophytes for efficient oxygen consumption in roots

Abstract

We evaluated the specific strategies of hydrophytes for root O(2) consumption in relation to N acquisition and investigated whether the strategies varied depending on the aeration capacity. Aeration capacity of roots is an important factor for determining hypoxia tolerance in plants. However, some hydrophytes possessing quite different aeration capacities often co-occur in wetlands, suggesting that root O(2) consumption also strongly affects hypoxia tolerance. We cultivated Phragmites australis with high aeration capacity and Zizania latifolia with low aeration capacity in hypoxic conditions with NH(4)(+) or NO(3)(-) treatment and compared the growth, N uptake, N assimilation and root respiration between the two species. In Z. latifolia grown with NH(4)(+) treatment, high N uptake activity and restrained root growth led to sufficient N acquisition and decrease in whole-root respiration rate. These characteristics consequently compensated for the low aeration capacity. In contrast, in P. australis, low N uptake activity was compensated by active root growth, but the whole-root respiration rate was high. This high root respiration rate was allowed by the high aeration capacity. The O(2) consumption-related traits of hydrophyte roots were closely correlated with N acquisition strategies, which consequently led to a compensational relationship with the root aeration capacity. It is likely that this functional linkage plays an important role as a core mechanism in the adaptation of plants to hypoxic soils.

Degradation of trinitrotoluene by transgenic nitroreductase in Arabidopsis plants

“…Additionally, the productivity of grain fertilized with N decreased with an increasing N application rate, and the productivity of grain fertilized with N in W 1 N 1 was higher than that of W 0 N 1 . There is in agreement with dissolved oxygen have positive effects on promoting the uptake of nitrogen and the increasing of rice yield , Nakamura et al 2013. Table 3 shows that NUE, NHI, NAE, NPE and productivity of rice fertilized with N were the highest under the W 1 N 1 .…”

“…Compared with W 0 , N accumulation at each stage of W 1 treatment were increased by 10.79% (tillering stage), 9.93% (jointing-booting stage), 8.93% (heading stage) and 6.57% (yellow ripening stage), respectively. It was mostly due to the increase in rhizosphere oxygen, so root respiration was strengthened, caused more energy to be provided for N absorption (Nakamura et al 2013).…”

Tolerant mechanisms to O2 deficiency under submergence conditions in plants

“…5). The decreased root growth (high S/R ratio) with sole NH 4 + treatment is more prominent in species with weak O 2 -supply system with only diffusion than in species with strong O 2 -supply system with pressurized gas flow (Nakamura et al 2013) (Fig. 5).…”

“…occultans, and C. middendorffii) are grown in the sole NH 4 + treatment under low O 2 condition, they exhibit a smaller root to shoot weight ratio (i.e., high S/R ratio) and increased net N uptake rate per unit root weight (NNUR) compared to the sole NO 3 − treatment. This high S/R ratio can lead to the decrease in the whole-root O 2 consumption in the sole NH 4 + treatment (Nakamura and Nakamura 2016;Nakamura et al 2010Nakamura et al , 2013 (Fig. 5).…”

“…Moreover, it was recently reported that the root O 2 consumption strategies related to nitrogen (N) acquisition differ among species with differences in their ability to O 2 supply to the roots. The differences in strategies are associated with the differences in the O 2 demand by the aerobic respiration for root growth and N acquisition (Nakamura and Nakamura 2016;Nakamura et al 2013). The N acquisition traits linked to the O 2 supply ability could relate to the hypoxia and anoxia tolerance in wild wetland species.…”