Brassica napus responses to short-term excessive copper treatment with decrease of photosynthetic pigments, differential expression of heavy metal homeostasis genes including activation of gene NRAMP4 involved in photosystem II stabilization

Abstract

In the present study, the influence of 50 and 100 µM CuSO4 was investigated starting from 3 h till 72 h treatment of 4-weeks Brassica napus plants. High CuSO4 concentrations in nutrient medium resulted in the rapid copper accumulation in plants, especially in roots, much slower and to lower degree in leaves. Copper excess induced early decrease in the leaf water content and temporary leaf wilting. The decrease in content of photosynthetic pigments became significant to 24 h of excessive copper treatments and reached 35 % decrease to 72 h, but there were no significant changes in maximum quantum efficiency of photosystem II photochemistry. The copper excess affected the expression of ten genes involved in heavy metal homeostasis and copper detoxification. The results showed the differential and organ-specific expression of most genes. The potential roles of copper-activated genes encoding heavy metal transporters (ZIP5, NRAMP4, YSL2, and MRP1), metallothioneins (MT1a and MT2b), low-molecular chelator synthesis enzymes (PCS1 and NAS2), and metallochaperones (CCS and HIPP06) in heavy metal homeostasis and copper ion detoxification were discussed. The highest increase in gene expression was shown for NRAMP4 in leaves in spite of relatively moderate Cu accumulation there. The opinion was advanced that the NRAMP4 activation can be considered among the early reactions in the defense of the photosystem II against copper excess.

The effect of excess copper on growth and physiology of important food crops: a review

“…In durum wheat cultivars, chlorophyll contents decrease about 35 % in Adamello and 55 % in Ofanto cultivar over control at 20 μM Cu in the culture medium (Ciscato et al 1997). In the rapeseed of mustard plants, reduction in content of photosynthetic pigments was 35 % with excessive Cu (100 μM) treatment to 72 h (Zlobin et al 2014).…”

“…More recently, Zlobin et al (2014) studied the expression of four metallochaperone genes, ATX1, CCS, HIPP05 and HIPP06, involved in metal homeostasis and Cu detoxification in rapeseed. Authors observed that Cu stress activated the expression of the CCS gene in both leaves and roots, while the expression of the HIPP06 and ZIP5 genes was activated only in the roots (Wu et al 2009).…”

Chromium Bioaccumulation and Its Impacts on Plants: An Overview

“…Hence, photosynthetic capacity of plants is compromised under Cr stress due to interaction with biosynthesis of chlorophyll molecules by inhibiting vital enzymes contributing in photosynthesis. Excessive Cr affects photosynthetic system by targeting the Calvin cycle enzymes, photosynthetic electron transport and thylakoid membrane [89]. Therefore, gradual decrease in the net photosynthetic rate can be observed in the plants treated with higher concentration of Cr [90].…”

Copper Uptake and Accumulation, Ultra-Structural Alteration, and Bast Fibre Yield and Quality of Fibrous Jute (Corchorus capsularis L.) Plants Grown under Two Different Soils of China

“…Previous studies showed that a high content of Cu in the soil causes a decrease in photosynthetic pigments [16,48]. Although Cu phytotoxicity affects both photosystems in plants, PS II is more sensitive than PS I to Cu stress [7,24,49].…”

“…ROS, which are toxic and remove by the activities of antioxidant compounds [18][19][20][21][22][23]. Previously, in many different crops, activities of high antioxidants were found such as in Boehmeria nivea [15], Phyllostachys pubescens [13] and Brassica napus [24] under Cu stress.…”