Allantoin involved in species interactions with rice and other organisms in paddy soil

Abstract

Allantoin (5-ureidohydantoin) plays an essential role in the assimilation, metabolism, transport, and storage of nitrogen in numerous higher plants, but its ecological implications are largely unknown. In this study allantoin was found in tissues of 11 rice (Oryza sativa) varieties tested, and its structure was characterised by X-ray diffraction analysis to confirm the fact that allantoin was actually obtained from the rice plants. Furthermore, the endogenous allantoin was exuded from the rice roots into the rhizosphere soils and had a great diversity of biological effects on associated weeds and microbes by soil interactions once released. However, allantoin levels in tissues or soils could not be distinguished between the allelopathic and non-allelopathic rice varieties. Field experiments showed that levels of allantoin released from rice varieties varied with their growth stages and reached the maximal levels at the stem elongation or panicle initiation to booting stages and then decreased dramatically. Allantoin could significantly stimulate the germination and growth of Echinochloa crus-galli and populations of soil bacteria and actinomycetes at selected test concentrations (30-500 mg/g), but had no effect on soil fungi. The half-life (t 1/2 ) of allantoin in autoclaved soil (20.2 ± 2.5 h, r 2 = 0.95) was almost three-times longer than in non-autoclaved soil (7.3 ± 1.9 h, r 2 = 0.92), indicating that rapid biodegradation or transformation of allantoin occurs in paddy soil. The results suggest that not only may allantoin play a role in the transport and storage of nitrogen in rice tissues but it may also participate in species interactions between rice and other organisms in paddy soil.

Crystal Structure Characterization of Natural Allantoin from Edible Lichen Umbilicaria esculenta

“…The monomeric unit in the crystal was found to have the C 4 -N 10 -C 11 -O 14 axis in the cis conformation and a conformation around the C 4 -N 10 bond that directs the O 14 atom to above the heterocyclic ring, so that the molecule assumes a 'scorpion like geometry [14]. The crystal data of natural allantoin isolated from lichen in the current study were also very close to those of crystalline structure of another natural allantoin from plant Oryza sativa (rice) [15], in which the crystal was found to be belong to space group P2 1 /c, with unit cell dimension parameters a = 8.013 (2) , final R indices R 1 = 0.0324, wR 2 = 0.0794. The crystal data of natural allantoin from lichen were a little different from those of the allantoin which were chemically synthesized by the oxidation and condensation reactions with ethandial and urea as starting materials [12], the crystalline structure of this synthesized allantoin was also determined by X-ray diffraction.…”

“…A few studies have shown that allantoin may act as an agent participating in chemical interactions between plants and other species [15]. Allantoin has been found in numerous plant species [20].…”

Allantoin-induced changes of microbial diversity and community in rice soil

“…These results imply that allantoin stimulates short-term rhizospheric processes for rice under natural conditions. However, the minimum effective concentration of allantoin in this study was greater (0.32 mM) than those detected in paddy soil (0.72 to 5.54 nM; Wang et al 2007). This controversial issue may be explained by that fact that in the previous study, the detection of allantoin was conducted using the bulk soil under arbitrary conditions, rather than detecting from the rhizosphere soil under intact conditions.…”

“…Allantoin not only plays an essential role in the assimilation, metabolism, transport, and storage of nitrogen in plants (Ninomiya et al 2004;Todd et al 2006;Zheng et al 2004), but it may also participate in chemical interactions between the plants and other species (Arlian and VyszenskiMoher 1996;Barbosa et al 1999;Wang et al 2007). In particular, allantoin produced and released from several plant species has been shown to have a stimulating effect on the germination and growth of other plants (Grassi et al 2005;Mallik and Williams 2005).…”

Assessing the Impact of Non‐Urea Ruminant Urine Nitrogen Compounds on Urine Patch Nitrous Oxide Emissions

“…However, the goal of this trial was to determine the fate of these compounds in the urine patch and to compare their residence time and lability in soil compared with urea. Both hypoxanthine and creatine degraded within their previously reported residence times (Dubos and Miller 1937; Wang et al, 2007). …”