Improvement of leaf K+ retention is a shared mechanism behind CeO2 and Mn3O4 nanoparticles improved rapeseed salt tolerance

Abstract

Salinity is a global issue limiting efficient agricultural production. Nanobiotechnology has been emerged as an effective approach to improve plant salt tolerance. However, little known is about the shared mechanisms between different nanomaterials-enabled plant salt tolerance. In this study, we found that both PNC [polyacrylic acid coated nanoceria (CeO2 nanoparticles)] and PMO (polyacrylic acid coated Mn3O4 nanoparticles) nanozymes improved rapeseed salt tolerance. PNC and PMO treated rapeseed plants showed significantly fresh weight, dry weight, higher chlorophyll content, Fv/Fm, and carbon assimilation rate than control plants under salt stress. Results from confocal imaging with reactive oxygen species (ROS) fluorescent dye and histochemical staining experiments showed that the ROS over-accumulation level in PNC and PMO treated rapeseed was significantly lower than control plants under salt stress. Confocal imaging results with K+ fluorescent dye showed that significantly higher cytosolic and vacuolar K+ signals were observed in PNC and PMO treated rapeseed than control plants under salt stress. This is further confirmed by leaf K+ content data. Furthermore, we found that PNC and PMO treated rapeseed showed significantly lower cytosolic Na+ signals than control plants under salt stress. While, compared with significantly higher vacuolar Na+ signals in PNC treated plants, PMO treated rapeseed showed significantly lower vacuolar Na+ signals than control plants under salt stress. These results are further supported by qPCR results of genes of Na+ and K+ transport. Overall, our results suggest that besides maintaining ROS homeostasis, improvement of leaf K+ retention could be a shared mechanism in nano-improved plant salt tolerance.

Plant salt response: Perception, signaling, and tolerance

“…In recent years, the plant nanobiotechnology approach has shown great potential to modulate plant stress response (Hofmann et al, 2020;Li et al, 2022). Nanotechnology is the application of small-sized materials with a basic structure of 1-100 nm (Farokhzad and Langer, 2009).…”

CsAKT1 is a key gene for the CeO2 nanoparticle's improved cucumber salt tolerance: a validation from CRISPR-Cas9 lines

“…70 While, PNC treatment significantly upregulated BnaHAK5 in the shoots but not in the root, compared with control plants under salt stress. 70 A similar case was shown in this study. Both leaf and root application of PNC could induce up-regulation of CsAKT1 and CsHAK5 , while the absolute expression of CsAKT1 was significantly higher than that of CsHAK5 , indicating that CsAKT1 is the most responsive gene for nanoceria-improved cucumber salt tolerance.…”

“…24 Similar results were shown in the PNC-treated rapeseed under salt stress, showing no significant change in the relative expression level of BnaGORK between PNC-treated rapeseed and control plants under salt stress, either in the root or in the leaf. 70 While, PNC treatment significantly upregulated BnaHAK5 in the shoots but not in the root, compared with control plants under salt stress. 70 A similar case was shown in this study.…”

Mn3O4 Nanoparticles Alleviate ROS‐Inhibited Root Apex Mitosis Activities to Improve Maize Drought Tolerance

“…The PMO was synthesized and characterized using as described in our previous method and some modification. [ 36 ] Briefly, 4.5 g PAA (MW 1800, Sigma Aldrich) and 0.425 g MnSO 4 ·H 2 O (AR, Sinopharm) were dissolved in 5 and 2.5 mL ultrapure water, respectively. Then two solutions were mixed at 2000 rpm for 15 min using a vortex mixer.…”

“…The labeling of PMO with 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethylindocarbocyanine (DiI, 97%, Sigma‐Aldrich) was done as described in our previous work. [ 36 ] In a 20 mL glass vial, 4.8 mL PMO (3 g L −1 ) and 200 µL DiI (dissolved in DMSO, 0.3 mg mL −1 ) were mixed at 1000 rpm for 1 min. The resulting mixture was transferred to a 10 kD dialysis bag and dialyzed in ultrapure water, the water was refreshed once every 8 h. After 24 h, the solution in the dialysis bag was labeled as DiI‐PMO and was stored in a refrigerator at 4 °C for further use.…”