Multifunctional Nanomaterials for Biofortification and Protection of Tomato Plants

Abstract

Calcium phosphate nanoparticles were doped with zinc ions to produce multifunctional nanomaterials for efficient agronomic fortification and protection of plants. The resulting round-shaped nanoparticles (nanoZn) were composed of 20.3 wt % Ca, 14.8 wt % P, and 13.4 wt % Zn and showed a pH-controlled solubility. NanoZn were stable in aqueous solutions at neutral pH but dissolved in citric acid at pH 4.5 (i.e., the pH inside tomato fruits), producing a pH-responsive delivery of the essential nutrients Ca, P, and Zn. In fact, the foliar application of nanoZn on tomato plants provided tomatoes with the highest Zn, Ca, and P contents (causing, respectively, a 65, 65, and 15% increase with respect to a conventional treatment with ZnSO4) and the highest yields. Additionally, nanoZn (100 ppm of Zn) inhibited in vitro the growth of Pseudomonas syringae (Ps), the main cause of bacterial speck, and significantly reduced Ps incidence and mortality in tomato seeds, previously inoculated with the pathogen. Therefore, nanoZn present dual agricultural applicability, enriching crops with nutrients with important metabolic functions in humans and simultaneously protecting the plants against important bacterial-based diseases, with considerable negative impact in crop production.

ZIF-8@Hydroxyapatite Composite as a High Potential Material for Prolonged Delivery of Agrochemicals

“…In fact, ZIF-8@HA exhibited statistically significant growth inhibition of Ps after 23 h, whereas ZIF-8 or Zn 2+ did not (Figure B). The combinatorial inhibition effect of ZIF-8 and HA NPs is ruled out since calcium phosphate NPs enhance Ps proliferation, as previously reported . Thus, the highest inhibition activity of ZIF-8@HA can be attributed to the stabilization effect of HA on its degradation profile, in agreement with the stability test (Figure S8).…”

“…The combinatorial inhibition effect of ZIF-8 and HA NPs is ruled out since calcium phosphate NPs enhance Ps proliferation, as previously reported. 37 Thus, the highest inhibition activity of ZIF-8@HA can be attributed to the stabilization effect of HA on its degradation profile, in agreement with the stability test ( Figure S8 ). Thus, ZIF-8@HA acts as a metal reservoir, making it more effective in the inhibition of the pathogen growth, as previously reported in other Zn-based materials.…”

“…at 630 nm (O.D.) 37 (see Section S5 for further details). Figure 6 A displays the growth rate of Ps in the presence of ZIF-8@HA, ZIF-8, and Zn 2+ , all of them at 50 ppm of Zn 2+ .…”

“…A stock bacterial suspension was prepared by introducing viablePsinto KB medium to attain a final optical density (O.D.) of around 0.1, according to a previous study . The following treatments were assessed: (i) bacterial control ( control ), (ii) Ps in the presence of ZnSO 4 (Zn 2+ ), (iii) Ps in the presence of ZIF-8@HA (ZIF-8@HA), and (iv) Ps in the presence of ZIF-8 (ZIF-8), all of them at 50 ppm of Zn.…”

“…of around 0.1, according to a previous study. 37 The following treatments were assessed: (i) bacterial control ( control ), (ii) Ps in the presence of ZnSO 4 (Zn 2+ ), (iii) Ps in the presence of ZIF-8@HA (ZIF-8@HA), and (iv) Ps in the presence of ZIF-8 (ZIF-8), all of them at 50 ppm of Zn. Additional details regarding the experimental conditions can be found in Table S1 .…”