Enhancing lettuce yield via Cu/Fe-layered double hydroxide nanoparticles spraying

Abstract

Layered double hydroxides (LDHs) have been widely used in the field of plant engineering, such as DNA/RNA transformation and enhancing plant disease resistance. However, few studies have examined the direct effects of LDHs on plants and their potential utility as nanofertilizers. In this study, the retention capacity of Cu/Fe-layered double hydroxide nanoparticles (CuFe-LDHs) was assessed by comparative experiments on vegetables. The results showed that the retention of CuFe-LDHs in leafy vegetables was high, such as lettuce. Phenotypic analysis revealed that the fresh and dry weights of lettuce leaves were both increased by spraying 10–100 μg/mL CuFe-LDHs. Using the optimal concentration of 10 μg/mL, we conducted further experiments to elucidate the mechanism of CuFe-LDHs promoting lettuce growth. It was found that the application of CuFe-LDHs had a significant effect on growth and induced physiological, transcriptomic, and metabolomic changes, including an increase in the chlorophyll b content, net photosynthetic rate, and intercellular carbon dioxide concentration, as well as modifications in gene expression patterns and metabolite profiles. This work provides compelling evidence that CuFe-LDHs can efficiently adsorb on the surface of lettuce leaves through hydrogen bonding, promote lettuce growth, mitigate the toxicity of heavy metal ions compared to their raw materials at the same concentration and offer a molecular-scale insight into the response of leafy vegetables to CuFe-LDHs. Graphical Abstract

Enhancing iron content and growth of cucumber seedlings with MgFe-LDHs under low-temperature stress

“…1 B, contrasting with the fine particles, likely soil particulates, present on the root hair surfaces of the plantlets of the CK and RW groups. Given our previous finding that CuFe-LDHs can bind to the cell surface through hydrogen bonds [ 23 ], it is plausible that these flakes represent MgFe-LDHs. The preferential accumulation of MgFe-LDHs on root hair surfaces, rather than on the cell walls of the mature region, is probably due to the predominant absorption of water and nutrients by the plant through the root hairs in the mature zone.…”

“…In this paper, we selected cucumber as a plant material to study the feasibility of using LDHs as a nanoiron fertilizer. As a continuation of our studies on LDHs in recent years [ 15 , 23 , 25 ], this study synthesized and characterized MgFe-LDHs and investigated their influence on cucumber seed germination, seedling emergence rate and growth under low-temperature stress and the associated cellular, physiological, and molecular mechanisms by combining transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma‒optical emission spectrometry (ICP‒OES), and liquid chromatography‒mass spectrometry (LC‒MS). This study is the first to report that MgFe-LDHs can improve plant nutrition.…”

“…Samples were harvested from the mature root zone, which is located 3–4 cm from the root growth point. Then, they were carefully excised, washed with EDTA-2Na, fixed in glutaraldehyde, postfixed in osmium tetroxide, dehydrated in ethanol (30–100%), and embedded in Spurr’s resin (Sigma, USA), following the methods of Wu et al [ 23 , 28 ]. Subsequently, three roots per treatment were sectioned using an LKB-V ultramicrotome, stained with 2% uranyl acetate and 0.5% lead citrate, and viewed under a JEM-1230 transmission electron microscope (Tokyo, Japan) at 80 kV.…”

“…Ribonucleic acid (RNA) extraction and transcriptome profiling from cucumber roots followed the methods of Wu et al [ 23 ]. Cucumber plants were treated for 10 days in a greenhouse with CK, LDH, or RW, as described in the “Seed germination, water uptake, seedling growth, and element content” section, with three replicates per treatment.…”

“…ramosa Hort.) growth [ 23 ]. We do not, however, know whether LDHs can serve as nanofertilizers under real soil or substrate conditions, which highlights the need to study their potential effects on plant growth.…”