Copper Toxicity on Photosynthetic Responses and Root Morphology of Hymenaea courbaril L. (Caesalpinioideae)

Abstract

Copper (Cu) is a micronutrient essential for plant development. However, in excess, it is toxic to plants and may cause various physiological and morphological changes. The study of the growth of plants exposed to excess Cu is important for the development of phytoremediation programs and for understanding the mechanisms involved in the tolerance of this metal. In this context, the objective of this research was to evaluate the effect of excess copper on photosynthetic responses and root morphology of Hymenaea courbaril L. Biometric measurements, gas exchange, root morphology, and Cu content in tissues and indices (TI and TF) were assessed, involving metal content and biomass. Up to a concentration of 200 mg kg −1 , Cu favored growth, gas exchange, and root morphology of the plants under study. At a higher concentration (800 mg kg −1) in the soil, it affected plant growth and caused a decrease in photosynthetic rate. Biochemical limitations in photosynthesis were observed, as well as lower maximum net photosynthetic rate (A max), respiration rate in the dark (R d), light compensation point (LCP), light saturation point (LSP), and apparent quantum yield (α), when exposed to excess Cu. Root length, surface area, mean diameter, root volume, dry biomass, and specific root length decreased with high Cu concentrations in the soil. Cu was accumulated in the roots as a mechanism of tolerance to the excess of this metal in order to preserve the most metabolically active tissues present in the leaves. At a concentration of 800 mg kg −1 , copper also caused inhibition of the root system. Plants of H. courbaril showed tolerance to excess Cu in the soil and can be indicated for the recovery of areas contaminated with this metal.

Responses of Phragmites australis to copper stress: A combined analysis of plant morphology, physiology and proteomics

“…Unfortunately, high concentrations of Cu can damage plant cells and affect plant growth and development. Excess Cu was found to reduce photosynthetic pigment content, photosynthesis and transpiration rates and F v /F m in plants (Ambrosini et al 2018; Khalid et al 2018; Marques et al 2018). More specifically, the tricarboxylic acid (TCA) cycle is disturbed and PSII (photosystem II) reaction centres are damaged (Küpper et al 2002; Zhao et al .…”

Physiological and biochemical changes in tree seedlings in an urban forest soil contaminated with copper

“…Decrease in A concurrent with increase, or no change, of Ci is a pattern found in several species grown on substrates contaminated with excess Cu (Vinit-Dunand et al 2002;Kevat and Sharma 2016;Hippler et al 2018, Li et al 2019 and probably caused by a decrease in rubisco activity and in the effectiveness of the Calvin-Benson cycle (Shahbaz et al 2015;Suganami et al 2020). These effects may result from changes in the plant's nutritional homeostasis caused by excess Cu in root cells, such as cell plasmolysis, retraction of the tonoplast and rupture / dysfunction of plasma membrane (Souza et al 2014), all of which can trigger changes in uptake, distribution, mobilization and regulation of other essential nutrients (Janicka-Russak 2012; Marques et al 2018;Zaouali et al 2020).…”

Mechanisms and Role of Nitric Oxide in Phytotoxicity-Mitigation of Copper

“…A large volume of literature is available on the impact of elevated Cu on major aspects in plants including germination and growth (López-Bucio et al, 2003;Lin et al, 2005;Mench and Bes, 2009;Potters et al, 2009;Bouazizi et al, 2010;Lequeux et al, 2010;Verma et al, 2011;Feigl et al, 2013;Gang et al, 2013;Muccifora and Bellani, 2013;Adrees et al, 2015;Marques et al, 2018), photosynthesis and related variables (Chatterjee and Chatterjee, 2000;Quartacci et al, 2000;Yruela, 2005;Küpper et al, 2009;Gonzalez-Mendoza et al, 2013;Mateos-Naranjo et al, 2013;Adrees et al, 2015;Feigl et al, 2015;de Freitas et al, 2015;Emamverdian et al, 2015;Sharma et al, 2017;Ambrosini et al, 2018), phenotypic changes (Barbosa et al, 2013;Feigl et al, 2013;Sánchez-Pardo et al, 2014;Adrees et al, 2015;Nair and Chung, 2015;Ali et al, 2016;Brunetto et al, 2016;Llagostera et al, 2016;Mwamba et al, 2016;Ambrosini et al, 2018;Shiyab, 2018;Marastoni et al, 2019b;Nazir et al, 2019;Shams et al, 2019), and nutrient-use-efficiency of plants (Chatterjee and Chatterjee, 2000;…”

“…During an early stage of growth, elevated Cu concentrations inhibited leaf expansion but increased pigment content (Maksymiec et al, 1994;Maksymiec and Baszyński, 1996;Adrees et al, 2015). In addition to inhibition in growth and biomass, Cu toxicity in plants also includes bronzing/necrosis (Marschner, 1995;Mench and Bes, 2009;Marques et al, 2018). Increasing Cu-concentration reduces uptake of Fe, Zn, Mn, and Co (Marschner, 1995;Bouazizi et al, 2010;Feigl et al, 2013).…”