Physiological and Molecular Investigation of Urea Uptake Dynamics in Cucumis sativus L. Plants Fertilized With Urea-Doped Amorphous Calcium Phosphate Nanoparticles

Abstract

At present, the quest for innovative and sustainable fertilization approaches aiming to improve agricultural productivity represents one of the major challenges for research. In this context, nanoparticle-based fertilizers can indeed offer an interesting alternative with respect to traditional bulk fertilizers. Several pieces of evidence have already addressed the effectiveness of amorphous calcium phosphate-based nanoparticles as carriers for macronutrients, such as nitrogen (N), demonstrating increase in crop productivity and improvement in quality. Nevertheless, despite N being a fundamental nutrient for crop growth and productivity, very little research has been carried out to understand the physiological and molecular mechanisms underpinning N-based fertilizers supplied to plants via nanocarriers. For these reasons, this study aimed to investigate the responses of Cucumis sativus L. to amorphous calcium phosphate nanoparticles doped with urea (U-ACP). Urea uptake dynamics at root level have been investigated by monitoring both the urea acquisition rates and the modulation of urea transporter CsDUR3, whereas growth parameters, the accumulation of N in both root and shoots, and the general ionomic profile of both tissues have been determined to assess the potentiality of U-ACP as innovative fertilizers. The slow release of urea from nanoparticles and/or their chemical composition contributed to the upregulation of the urea uptake system for a longer period (up to 24 h after treatment) as compared to plants treated with bulk urea. This prolonged activation was mirrored by a higher accumulation of N in nanoparticle-treated plants (approximately threefold increase in the shoot of NP-treated plants compared to controls), even when the concentration of urea conveyed through nanoparticles was halved. In addition, besides impacting N nutrition, U-ACP also enhanced Ca and P concentration in cucumber tissues, thus having possible effects on plant growth and yield, and on the nutritional value of agricultural products.

Nanosized Calcium Phosphates as Novel Macronutrient Nano-Fertilizers

“…More recent research [ 61 ] aimed at understanding the molecular response of the urea uptake mechanism demonstrated that the slow release of urea from urea-loaded ACP nanoparticles could contribute to upregulating the urea uptake system for a longer period as compared to plants treated with bulk urea only. Indeed, such extended activation, studied by the expression analysis of the DUR3 gene (a transporter devoted to the transmembrane translocation of urea), was mirrored by the higher accumulation of N in NP-treated plants, even when the supplied urea concentration was halved (i.e., in the NP0.5 treatment) confirming; therefore, the higher performance previously described.…”

Plant growth promoting potential of urea doped calcium phosphate nanoparticles in finger millet (Eleusine coracana (L.) Gaertn.) under drought stress

“…The deposition of lignin and suberin in the roots is controlled by N ( Gao et al., 2017 ). In a study on C. sativus , foliar application of CaP-U NPs provided approximately a three-fold increase in the shoot length, as compared to the control, as well as increased nitrogen (N), calcium (Ca) and phosphorus (P) accumulation in both root and shoot ( Feil et al., 2021 ). In wheat crops, foliar application of the chitosan nanoparticles loaded with nitrogen, phosphorus and potassium (NPK) increased shoot length and grain yield substantially ( Abdel-Aziz et al., 2016 ).…”

Effects of nano urea on growth and gene expression ofArabidopsis thalianain hydroponics

“…For example, in cucumber, a hydroponic application of a nanoformulation of urea induced higher expression levels of the high-affinity urea transporter gene CsDUR3 than conventional urea. In addition, CsDUR3 induction was observed over a more extended period in NUF-treated plants than in urea, leading to an extended uptake (Feil et al, 2021). Hydroponic application of a nano copper fertilizer in wheat led to a lower up-regulation of NRT genes and genes encoding auxin efflux proteins than bulk copper fertilizers.…”