Copper Trafficking in Plants and Its Implication on Cell Wall Dynamics

Abstract

In plants, copper (Cu) acts as essential cofactor of numerous proteins. While the definitive number of these so-called cuproproteins is unknown, they perform central functions in plant cells. As micronutrient, a minimal amount of Cu is needed to ensure cellular functions. However, Cu excess may exert in contrast detrimental effects on plant primary production and even survival. Therefore it is essential for a plant to have a strictly controlled Cu homeostasis, an equilibrium that is both tissue and developmentally influenced. In the current review an overview is presented on the different stages of Cu transport from the soil into the plant and throughout the different plant tissues. Special emphasis is on the Cu-dependent responses mediated by the SPL7 transcription factor, and the crosstalk between this transcriptional regulation and microRNA-mediated suppression of translation of seemingly non-essential cuproproteins. Since Cu is an essential player in electron transport, we also review the recent insights into the molecular mechanisms controlling chloroplastic and mitochondrial Cu transport and homeostasis. We finally highlight the involvement of numerous Cu-proteins and Cu-dependent activities in the properties of one of the major Cu-accumulation sites in plants: the cell wall.

Plant Endomembrane Dynamics: Studies of K+/H+ Antiporters Provide Insights on the Effects of pH and Ion Homeostasis

“…Cu binding to apoproteins in post-Golgi compartments is likely conserved in plants. Cu is transported into and out of endomembrane compartments through AtHMA5, a Cu pump, and other Cu transporters (Blaby-Haas and Merchant, 2014;Printz et al, 2016). Plants possess multicopper oxidases, like extracellular laccases (Turlapati et al, 2011) and apoplastic ascorbate oxidases.…”

Arabidopsis Pollen Fertility Requires the Transcription Factors CITF1 and SPL7 That Regulate Copper Delivery to Anthers and Jasmonic Acid Synthesis

“…In addition to these functions, plants require Cu for the perception of hormones, cell wall dynamics, and response to pathogens and reproduction (Shorrocks and Alloway, 1988;Ravet and Pilon, 2013;Mendel and Kruse, 2012;Printz et al, 2016;Broadley et al, 2012). Cu deficiency in humans is an increasingly recognized cause of anemia (Daughety and DeLoughery, 2017) and the dramatic consequences of imbalanced Cu homeostasis are known as Menkes and Wilson diseases (Llanos and Mercer, 2002).…”

Influence of Grafting on the Copper Concentration in Tomato Fruits under Elevated Soil Salinity

“…Studies on micronutrient levels required for plant growth have shown that salinity is an important factor in determining micronutrient availability (Richards, 1954). Copper is classified as one of the essential micronutrients in plant nutrition, which acts as a cofactor of numerous enzymes and has a vital role in cellular functions (Printz et al 2016). As a transition metal Cu in plant cells appears in two forms: the reduced Cu + state and the oxidized Cu 2+ state.…”