Overexpression of exogenous biuret hydrolase in rice plants confers tolerance to biuret toxicity

Abstract

Urea, currently the most widely used nitrogen (N) fertilizer worldwide (IFASTAT, https://www.ifast at.org/datab ases), might contain biuret [(CONH 2) 2 NH], as a common impurity. Biuret is formed by the thermal condensation of urea. It has been known since the 1950s that excessive amounts of biuret in urea fertilizers cause injury in crops (Jones, 1954; Sanford et al., 1954). A wide range of crops can be potentially affected by biuret toxicity, which often manifests as leaf chlorosis and stunted growth, especially in the young seedling stage (Mikkelsen, 1990). Earlier studies indicated that biuret inhibited protein synthesis in Xanthium pensylvanicum leaves (Webster et al., 1957) and wheat (Triticum aestivum) germplasms (Ogata & Yamamoto, 1959). The protein content, however, did not so much decrease in biuret-injured orange (Citrus sinensis) leaves (Impey & Jones, 1960). It remains uncertain whether biuret has a direct effect on the protein synthetic machinery. Additionally, ultrastructural analyses showed that changes in chloroplast structure in biuret-injured leaves were similar to those in senescent leaves in grapefruit (Citrus paradise) and orange plants (Achor & Albrigo, 2005). Moreover biuret seems to remain unmetabolized in plants, because it was still detected in orange leaves, eight months after foliar spraying was performed (Impey & Jones, 1960). The exact mechanism underlying biuret toxicity in plants, however, is still far from being understood.

Meloidogyne enterolobii-induced Changes in Guava Root Exudates Are Associated With Root Rotting Caused by Neocosmospora falciformis

“…Some soil bacteria use the enzyme biuret hydrolase to decompose biuret ( Cameron et al, 2011 ; Aukema et al, 2020 ). Interestingly, transgenic rice plants overexpressing biuret hydrolase have a higher tolerance to biuret toxicity ( Ochiai et al, 2020 ), suggesting that biuret hydrolase is important in circumventing the phytotoxicity of biuret. In the present work, in silico analysis showed that 1,5-dinitrobiuret complexes with biuret hydrolase have an energy equivalent to N -formyl-D-aspartic acid, which is the enzyme’s inhibitor.…”

Nitrogen Fertilizers Technologies for Corn in Two Yield Environments in South Brazil

“…Although biuret is a common impurity, Brazilian legislation allows only up to 2% in solid N fertilizer [ 46 ], because it is a toxic chemical compound that interferes with the protein synthesis of plants [ 47 ]. Currently, biuret toxicity is insignificant in crops, due to advances in the technology used to manufacture urea fertilizers [ 48 ]. Although Ur-formaldehyde comes from an amidic source, biuret was not found in the XRD analysis, probably due to strict controls in the production process.…”

One-Pot Synthesis and Hydrolysis Behavior of Highly Water-Soluble Ammonium Polyphosphate

“…Some side reactions are inevitable in the polymerization process, including the decomposition of urea and the formation of a condensed biuret. Among them, biuret is the main byproduct of APP products, and the content of biuret in fertilizer products should be strictly controlled because it causes damage to crops. − The reaction equations for the thermal decomposition of urea and the formation of condensed biuret are shown in eqs and , respectively. …”