Differential Aquaporin Response to Distinct Effects of Two Zn Concentrations after Foliar Application in Pak Choi (Brassica rapa L.) Plants

Abstract

Zinc (Zn) is considered an essential element with beneficial effects on plant cells; however, as a heavy metal, it may induce adverse effects on plants if its concentration exceeds a threshold. In this work, the effects of short-term and prolonged application of low (25 µM) and high (500 µM) Zn concentrations on pak choi (Brassica rapa L.) plants were evaluated. For this, two experiments were conducted. In the first, the effects of short-term (15 h) and partial foliar application were evaluated, and in the second a long-term (15 day) foliar application was applied. The results indicate that at short-term, Zn may induce a rapid hydraulic signal from the sprayed leaves to the roots, leading to changes in root hydraulic conductance but without effects on the whole-leaf gas exchange parameters. Root accumulation of Zn may prevent leaf damage. The role of different root and leaf aquaporin isoforms in the mediation of this signal is discussed, since significant variations in PIP1 and PIP2 gene expression were observed. In the second experiment, low Zn concentration had a beneficial effect on plant growth and specific aquaporin isoforms were differentially regulated at the transcriptional level in the roots. By contrast, the high Zn concentration had a detrimental effect on growth, with reductions in the root hydraulic conductance, leaf photosynthesis rate and Ca2+ uptake in the roots. The abundance of the PIP1 isoforms was significantly increased during this response. Therefore, a 25 µM Zn dose resulted in a positive effect in pak choi growth through an increased root hydraulic conductance.

Collaborative Assessment and Health Risk of Heavy Metals in Soils and Tea Leaves in the Southwest Region of China

“…Other studies reported similar findings for Pu’er and black tea [ 27 , 36 ]. Therefore, Cr contamination in tea leaves needs special attention and prevention measures, such as spraying leaf tissue control agents to reduce Cr absorption in tea leaves [ 37 ] and finding tea varieties with a reduced risk of Cr accumulation [ 26 ].…”

Foliar Application of Zn Alleviates Salt Stress Symptoms of Pak Choi Plants by Activating Water Relations and Glucosinolate Synthesis

“…(ii) (Zn solutions: 3 mL per plant, containing zinc sulphate at concentrations of 50, 100, 500 or 1000 µM, with 0.1% non-ionic, organo-silicon surfactant, were sprayed onto the leaves three times a week for one week. As we had found previously that 25 µM zinc sulphate did not produce any negative effect on plant biomass [32], in this experiment, to check the levels of toxicity, the lowest concentration was 50 µM.…”

Arbuscular Mycorrhiza-Mediated Regulation of Polyamines and Aquaporins During Abiotic Stress: Deep Insights on the Recondite Players

“…The regulatory influence of HMs on AQP activity and expression has been validated in several plants, like Hgstressed Pisum sativum (Beaudette et al, 2007), Cu-stressed Mesembryanthemum crystallinum (Kholodova et al, 2011), arsenic [As (III)] exposed Brassica juncea (Srivastava et al, 2013), HMs (Zn 2+ , Pb 2+ , Cd 2+ , and Hg 2+ ) stressed Allium cepa that accounted to metal-induced drop in water permeability in the order of Hg 2+ > Cd 2+ > Pb 2+ > Zn 2+ (Przedpelska-Wasowicz andWierzbicka, 2011), Zn-stressed poplar (Ariani et al, 2019), and Brassica rapa (Fatemi et al, 2020). Multiple reports validate the significance of AQP activity as efflux transporters that excrete HMs out of the cellular space (Vats et al, 2021).…”