Root and Shoot Response to Nickel in Hyperaccumulator and Non-Hyperaccumulator Species

Abstract

The soil–root interface is the micro-ecosystem where roots uptake metals. However, less than 10% of hyperaccumulators’ rhizosphere has been examined. The present study evaluated the root and shoot response to nickel in hyperaccumulator and non-hyperaccumulator species, through the analysis of root surface and biomass and the ecophysiological response of the related aboveground biomass. Ni-hyperaccumulators Alyssoides utriculata (L.) Medik. and Noccaea caerulescens (J. Presl and C. Presl) F.K. Mey. and non-hyperaccumulators Alyssum montanum L. and Thlaspi arvense L. were grown in pot on Ni-spiked soil (0–1000 mg Ni kg−1, total). Development of root surfaces was analysed with ImageJ; fresh and dry root biomass was determined. Photosynthetic efficiency was performed by analysing the fluorescence of chlorophyll a to estimate the plants’ physiological conditions at the end of the treatment. Hyperaccumulators did not show a Ni-dependent decrease in root surfaces and biomass (except Ni 1000 mg kg−1 for N. caerulescens). The non-hyperaccumulator A. montanum suffers metal stress which threatens plant development, while the excluder T. arvense exhibits a positive ecophysiological response to Ni. The analysis of the root system, as a component of the rhizosphere, help to clarify the response to soil nickel and plant development under metal stress for bioremediation purposes.

Phytoremediation Potential of Native Hyperaccumulator Plants Growing on Heavy Metal-Contaminated Soil of Khatunabad Copper Smelter and Refinery, Iran

“…By definition, when a plant concentrates 1000 mg/kg dry weight of metals such as Ni, Co, Cu, Pb, and Zn in its aboveground tissues, it can be called a hyperaccumulator [42]. However, the threshold value for Mn and Zn is 10,000 mg/kg [56], and for Cd, it is greater than or equal to 100 mg/kg [16].…”

“…Rosatto et al [42] studied the response of roots and shoots to Ni in hyperaccumulator and non-hyperaccumulator plant species. They focused the study on the species Alyssoides utriculata (L.) Medik.…”

Morley: Image Analysis and Evaluation of Statistically Significant Differences in Geometric Sizes of Crop Seedlings in Response to Biotic Stimulation

“…ImageJ [23] is widely applied for image analysis of plants and seedlings [24][25][26][27][28] and solves similar tasks as Morley. ImageJ allows for the calculation of the surface areas, lengths, mean values, and standard deviations.…”

“…In this case, the lengths, angles, surface areas, and numbers of plant organs are of interest. Leaf, shoot, and root lengths and surface areas of seedlings are often measured using ImageJ, a freely available tool for multi-purpose image analysis [23][24][25][26][27][28]. At the same time, analysis with ImageJ is often restricted to a few dozen plants due to the difficulty when manually pre-processing images in order to select the objects of interest.…”

A Mini-Review on the Co-growth and Interactions Among Microorganisms (Fungi and Bacteria) From Rhizosphere of Metal-Hyperaccumulators

“…Another study by Rosatto et al ( 2021a , b ) was conducted on the root development with respect to metals and possible interactions of bacteria and microfungal strains isolated from the rhizosphere of the facultative hyperaccumulator Alyssoides utriculata , showing how only a few species built positive relations and co-grew with it. The best performing strains in terms of Ni tolerance and PGP traits were subjected to in vitro tests to establish mutual interactions and identify a clear synergy between the bacterial and the fungal component (Rosatto et al, 2021a ).…”